Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident


Volume 4 Index


Hearings of the Presidential Commission on the Space Shuttle Challenger Accident: February 6, 1986 to February 25, 1986


Centered number = Hearing page
[bold number] = Text page.





Washington, D.C.

The Commission met, pursuant to recess, at 10:10 a.m.


WILLIAM P. ROGERS, Chairman, Presiding
NEIL A. ARMSTRONG, Vice Chairman
AL KEEL, Commission Executive Director





CHAIRMAN ROGERS: I would like to call the Commission to order, please.

Yesterday we had a meeting in executive session, at which time the NASA officials and others produced documents at our request, and memoranda, dealing principally with the O-rings and seals on the booster rockets. They complied fully with the request that we made and were very forthcoming in discussing all aspects of it that we were able to discuss at the meeting.

This morning we will start the meeting with officials from NASA, particularly dealing with the matter of seals on the booster rockets. And I would like as much as possible to limit our discussions today to that one subject matter.

We will attempt to advise the press of our plans as they are formulated, so that you can plan your own schedules. We are contemplating at the moment tomorrow having a day off, hopefully to get a little better organized and getting our staff organized. On Thursday, we plan to go to Kennedy and probably stay over Friday in order to see the facilities, discuss with the NASA officials all aspects of the launch, and to be available to have presented to us any other matter that




NASA feels would be appropriate.

During that time we will have informal discussions with people. We expect those will not be open sessions, because physically it is impossible. We may divide into subcommittees or we may [328] have individual interviews, but we will keep you advised about that. We would hope at that time, keeping in mind that we are going to focus today on the seals of the booster rockets, we would hope at that time that NASA will be in a position to show us and to show the media more of the pictures of the flight itself.

And also, we hope that we will be able to get some more information about telemetry and measurements that are being studied now. We want to do this in a way that will not be intrusive as far as the investigations under way are concerned, but we want to get as much information as quickly as we possibly can.

Later on - and I'm not sure when, probably next week - we will have meetings, either in executive session or closed meetings, dealing with the problems involving the weather and all of the weather-related problems, and we will take testimony from the Thiokol people and from NASA officials and get information about meetings that were held prior to the launch, all aspects of the weather and how the weather might have related to




the launch.

So today we will start with NASA officials, and first I would like to ask Dr. Graham, the Acting Administrator of NASA, to take the stand and address the Commission.







DR. GRAHAM: Good morning, Mr. Chairman. Do you wish to swear me in or shall I proceed?

CHAIRMAN ROGERS: No, you have been sworn in. You may proceed.

DR. GRAHAM: Thank you.

Mr. Chairman, members of the Presidential Commission on the Challenger Accident: I would like to assure you that NASA is continuing to review the facts and circumstances surrounding the accident that occurred with the Challenger.

As NASA continues to analyze the system design and data, as I said at the meeting last Thursday, you can be certain that NASA will provide you with its complete cooperation. In keeping with that, we have implemented several procedures.

One of them is that all NASA testimony that is given to the Commission will be reviewed on a word by word basis by a knowledgeable NASA technical review team. Should any error, partial, or incomplete statement, or potentially misleading statement be found in the testimony, an amendment to the testimony will be filed in order to clarify the issue of concern. That will certainly be called to your attention.




In addition to that, the NASA policy concerning the release of material is that NASA is making available to the Commission and then to the press and the public all information related to the tests that we have in NASA reviewed and which we find to be reasonably factual and not grossly misleading. We will continue that policy and, while I am sure that there will be concerns on NASA's part and as well as elsewhere over the time it takes to review some of this mass of information, to pull it together, and to provide it in a form that can be distributed to the press, nevertheless we are making very, very substantial efforts to have that information available to you and then subsequently to the public as quickly as we possibly can.

[329] Do you have any questions, Mr. Chairman, concerning that, before I go on to introduce the next speaker?

CHAIRMAN ROGERS: Yes. I would like to have a discussion with you about that first. Are there many confidential or classified documents among the documents in your possession?

DR. GRAHAM: There are very few that we have found to date, Mr. Chairman, that are of a national security nature that are classified.

CHAIRMAN ROGERS: So you will be able to make




all the documents available, in the final analysis, to the public?

DR. GRAHAM: Within the constraints of the law, either constraints concerning national security issues or constraints concerning technical export or transfer, we may have to exercise some discretion on a very, very small set of the documents. But in general, and certainly the vast bulk of the information, the relevant material and the data will be released to the public. And of course, all data is accessible to the Commission.

CHAIRMAN ROGERS: Now, there is no feeling on the part of NASA that the work of the Commission is in any way interfering with the disclosure of information, I hope?

DR. GRAHAM: No, sir. In fact, the work of the Commission is very much in accord with the work that NASA is undertaking and conducting internally, and we find these to be in general complementary.

CHAIRMAN ROGERS: In fact, you asked me to have this public session today in order to make it clear that NASA was not trying to brush anything under the rug, isn't that right?

DR. GRAHAM: Yes, sir. I suggested to you that you consider having a public session today on




specific characteristics of the SRB's, the solid rocket boosters, and any other matters you saw fit to question the NASA officials concerning.

CHAIRMAN ROGERS: I assume that there are thousands and thousands of documents that you are now considering for purposes of the investigation and for purposes of this Commission, is that right?

DR. GRAHAM: Yes, sir, a large number of internal documents that we have in review and consideration. We plan to release to the press today at the conclusion of this discussion the material that will be presented to you or is being presented to you today. And then tomorrow NASA will have a press briefing, and at that time we plan to release the entire bulk of the material that was released and presented to the Commission yesterday.

The amount of that material alone is a stack probably close to three inches high, and that is just a small part of the total data that we are reviewing and preparing for transmission to you and to release.

CHAIRMAN ROGERS: In light of the memorandum which has appeared in the press, written by Mr. Cook to Mr. Davis - and incidentally, those gentlemen are here today and will appear and testify - I assume that there are a lot of other documents of that nature, which make




suggestions about how matters should proceed, pointing out risks that were involved in launches, et cetera, is that correct?

DR. GRAHAM: Yes, sir. In any highly sophisticated technical operation such as the operation of the space shuttle system, there has to be a continuing dialogue within the agency that is responsible for operating it concerning the performance of the system, the characteristics, how [330] well the design is behaving in comparison with the operational data and the design expectation of the system.

All that is being constantly cross-checked and reviewed and re-analyzed, and you will find that there is a substantial volume of information that documents that process inside NASA, and we will make that available to you as soon as we have a chance to accumulate it and put it together in a form that is comparable.

CHAIRMAN ROGERS: The point I'm making is it's not unusual in an agency like yours to have employees make critical comments, suggest dangers that might be involved in the program. That is the way the system works, isn't it?

DR. GRAHAM: Yes, sir. It is very, very important, in fact, for the system to work to be somewhat




self-critical, and in the process of operating these systems to constantly review the issues, the engineering decisions, the performance. That internal self-criticism is in fact one of the strongest characteristics of NASA and one of the things that makes it in my view such a high quality technical operation.

CHAIRMAN ROGERS: And it may very well be that there will be a lot of other memoranda that appear in the press that neither you nor we know about? That would not be unusual at all, would it?

DR. GRAHAM: I wouldn't be in the least bit surprised if other issues come forward as we proceed through this review process.

CHAIRMAN ROGERS: And if we focus today on, to some extent on seals and O-rings and memoranda that are written by Mr. Cook and others dealing with that subject, the fact that we focus on it doesn't mean that that is the only area of concern as far as you're concerned or as far as the Commission is concerned, is that right?

DR. GRAHAM: No, sir, it is not the only area where we will find memoranda expressing engineering issues and engineering concerns. And it certainly doesn't mean that the NASA internal analyses has singled out any one area at this point - the O-rings, the seals, the field joints, or any other specific area -




as a unique source of concern and analysis.

We are still looking across a broad range of issues to try to establish what actually occurred in the Challenger accident.

CHAIRMAN ROGERS: Very well. Then the Commission will try in an orderly way to consider each one of those aspects, so at the end of our deliberations we will have a complete record of all of the documents in your possession and a complete record of the pictures and telemetry and all other aspects of it, that will help us make a judgment.

And I thank you very much for this colloquy. Maybe other members of the Commission might want to ask some questions.

DR. FEYNMAN: I wanted to say that there's as aspect of trying to figure out exactly what happened, in that first something looks obvious. Then, it is the experience of Commissions who have looked into accidents that what looks obvious at first turns out later to have a little flaw, and, when you make a long list of things that are out of the ordinary, that are called anomalies, you discover that there is something that doesn't quite fit, and then the theory has to be completely changed.

So that kind of work we don't want to have to drag the public through. We're thinking of


[331] 604


possibility A, possibility B, possibility C, and as we go through all of these things all the newspapers are always saying, now they think it is this, now they think it is that.

We don't know what it is, and we would like to investigate that physical question, I should hope, if it is at all possible, without the public directly, and then we can give a complete report. But when we are discussing this particular matter, it doesn't imply that this is what was the cause of the accident, but as an example the kind of thing that we have to investigate.

I don't think you should conclude that we know that this is directly related or whether it is or it isn't directly related. Certainly it is information we have to have to the actual accident.

DR. GRAHAM: Yes, sir.

CHAIRMAN ROGERS: I think there is one other aspect that deserves some comment at this point. Usually in investigations of this kind, you find that the press is not very knowledgeable on the subject and therefore the reporting is not very accurate. It seems to me that in this case the reporting has been quite fair and accurate on the part of the press, partly because they know a lot about it and they have followed it very closely.




And so I hope that we don't develop any friction between the media and NASA and this Commission, because we are all working to the same end. And as far as I can tell up to date, it has been a very fair process on the part of the media, and I hope we can cooperate with them in all ways to deal with this very difficult and tragic accident, which is of such importance to the nation.

All right, Doctor, you may proceed.

DR. GRAHAM: Thank you. Mr. Chairman. And that is certainly our intention, to proceed in just that manner.

I would like to now introduce the Associate Administrator for Space Flight, Mr. Jesse Moore. Mr. Moore plans, directs, and executes the development, acquisition, testing, and operation of all elements of the space transportation system within NASA and, as I mentioned last week, he has also been named as the director, the new director of the Johnson Space Flight Center at Houston.

Mr. Moore.






MR. MOORE: Mr. Chairman and members of the Presidential Commission:

What I would propose to do today is to give you a short status report of what my task force is doing and the areas we are focusing in on, and then I would like to call on the project manager of the solid rocket booster from the Marshall Space Flight Center to discuss with you and members of the Commission the solid rocket booster aspects and to try to address some of the issues that have been raised before the public here and to let you, as well as the public, know what actions have been taken with the solid rocket booster and what its functions are and so forth.

So that is kind of the agenda that I plan to cover this morning.

(Viewgraph.) [Ref. 2/11-1]

[332] I would like to say at the outset that I think the discussion that you and Dr. Graham had lays a very good foundation for the type of work we're conducting in our task force. We plan to cooperate very fully with the Commission and provide the data to the Commission as required.

As you indicated and Dr. Graham indicated,




there is an enormous amount of data that is available on all aspects of the space shuttle, and we will pull and are pulling all relevant documents together related to the 51-L tragic accident.

On February 5th, Dr. Graham formed a data analysis design task force on the 51-L mission incident. I am chairing that task force.

(Viewgraph.) [Ref. 2/11-2]

This was a transition from an interim mishap board that I had been chairing previously, and we're in the process now of formally establishing our charter and our membership. We had our first organization meeting at the Kennedy Space Center yesterday. I was obviously unable to attend, but the group is meeting, and we are preparing a list of and setting up a group of panels to address specific areas associated with the space shuttle 51-L mission incident.

We are planning to include on our panels, as well as the overall task force, members not only from NASA, but members from the outside to address specific areas of expertise as far as this overall incident is concerned.

Where we are today is we are continuing our salvage operations to try to find as much physical evidence as we possibly can that would allow us to piece




together the set of circumstances that caused the 51-L tragedy

(Viewgraph.) [Ref. 2/11-3]

In the area of data analysis, which is one of the most complex areas to try to look at, our primary concentration is to try to reconstruct a mission events time line, and this time line will tell us in great detail the sequence of events that went on from launch until the incident happened, some 70-plus seconds later.

We are looking at photographic data, and you mentioned that earlier in your opening comments. We will share some of that data with you in Florida on Thursday, and we are also trying to understand what load effects might have been applied to Challenger's launch, meaning there are different forces that we don't understand that happened during the trajectory: Were there any unusual set of circumstances happening prior to launch that we need to know about?

And our efforts are aimed at trying to get what I'd call an integrated load picture of what the flight looked like during pre-launch as well as during its ascent.

And you mentioned weather. Weather is certainly an issue that we're going to be working very




hard and are working very hard to try to understand what effects, if any, the weather played. We will be looking at temperature effects. We will be looking at wind conditions, not only surface wind conditions but upper atmospheric wind conditions, as well as moisture conditions, rain content, and so forth.

All these will be looked at in very great detail, and we will be happy to discuss weather activities with you and the Commission at your discretion.

CHAIRMAN ROGERS: On that subject, in preparation for hearings it would be useful if we had a scenario worked out of conferences and meetings and discussions, so that we can have a narrative form of what happened, in addition to all of the weather data itself.

[333] MR. MOORE: I presented to you and the Commission, I guess last week when we had the public hearing, that there were a number of mission meetings held in the chronology of this launch. We will go back, and are doing it right now, expanding that chronology, so we will be able to talk to you and the Commission in great detail on the weather aspects associated with this launch.


MR. MOORE: In addition to things like




weather, loads, and other kinds of effects, it is critical to understand the pedigree of the hardware, how the particular hardware was processed, who handled the hardware, what kind of safety inspections were performed, and how many times the hardware had been used, and so forth. So these areas are also being looked at in very, very great detail.

There is a very complex procedure set up to apply and reuse hardware from the various shuttle flights and, as you know, there are two major elements that are reuseable from the shuttle flights. The shuttle orbiter certainly is reuseable, as well as the two solid rocket boosters are reuseable. They are launched and deployed, and we bring those boosters back in, refurbish those boosters to a certain set of specifications, and then refly those boosters on subsequent missions.

You asked a question of us the other day that I would like to answer. A new set of solid rocket boosters, flight set, meaning two of them, costs about 65, $66 million, is what a brand new set costs. A refurbished set costs on the order of 22 to 23, $24 million.

So there is about a factor of three in terms of cost relative to buying new flight sets of SRB's for




each flight versus the reusing of these flight sets. And so I thought I would present that piece of data to you, to answer one of your questions that you talked about.

Another element that is very important in this particular launch is the launch pad. This was the first time we had launched a mission off pad B. Our previous 24 launches had been on launch pad A at the Cape, and we are clearly spending a lot of time looking at any differences there may be relative to the two launch pads that were used.

We were carrying some cargo on board this flight. We were carrying a Tracking and Data Relay Satellite system, as well as a Spartan-Halley. We had flown the Tracking and Data Relay Satellite system and the inertial upper stage before, but we are trying to find out, were there any unusual circumstances associated with that.

No STS element - and "STS" is "Space Transportation System" - will be left unturned. No stone will be left unturned. We are not exonerating any aspect of this particular mission as far as free from either being a cause or an effect from the tragic incident that happened on 51-L.

We are putting together, as has been




previously discussed, several of what I would call failure scenarios. These are things that could go wrong, and we are putting those together across all parts of the program. And our job in this task force is to try to go and prove each of these scenarios did not contribute to this accident, and we are doing that by analysis and by tests that are being conducted now.

(Viewgraph.) [Ref. 2/11-4]

And also by test data that has been previously run in the program. And so that will be a process we will be going through to discount and to say conclusively that this particular failure scenario was not a contributor in the 51-L mission incident.

[334] CHAIRMAN ROGERS: Jesse, based upon what you told us before, though, you have been doing that each time, haven't you? I mean, this analysis is not new to 51-L?

MR. MOORE: We have failure modes and effects analysis for all elements of the shuttle, and that has been done and documented, and we're using those failure modes and effects analyses that are in the program as starting points for the kind of analysis that we're doing right now, Mr. Chairman.

CHAIRMAN ROGERS: Good, because we wouldn't want to leave the impression that you're doing it just




because of this accident. Your records indicate you have been doing this on a regular basis.

MR. MOORE: Yes, sir. It has been done since the program, since the start of the program, as part of the normal analysis of a system like this where you do go through and do detailed failure modes and effects analysis and so forth.

And what we're trying to do is make sure that what has been documented and known and done in the program is consistent with the postulates that we're putting forward now, that may have been a cause relative to the 51-L mission.

We are also trying to be very careful and discriminating between cause and effect, and it is easy to say, here's a picture that shows a piece of information, but that piece of information may have been the result of some other cause. And so we are trying to be very careful and discriminating between cause and effect as far as where we are focusing in on the problems with respect to this accident.

The solid rocket booster is obviously one area that we are focusing very heavily on, and I will say a little bit more about that, and that is the purpose of our agenda here today, is to try to tell you and the Commission what we're doing in




the solid rocket booster area and some of the potential areas that are of concern relative to the solid rocket booster.

The external tank is also involved in one or more scenarios as far as potential failure modes in this whole program, as well as the other elements, as I said earlier. And I would like to emphasize to the Commission that we have not exonerated any aspect of the 51-L mission as of now.

Finally, with respect to the solid rocket booster, we are looking at things like design specifications, materials that are used, the manufacturing process that was used, how the system was stacked and how it was prepared for launch, who was involved, the safety aspects of it, the quality assurance aspects of it, any photography that we have which closes out the work prior to a launch, and we do that on a routine basis, take photographs -

(Viewgraph.) [Ref. 2/11-5]

- of the flight hardware at various stages during its preparation for launch. And we call those closeout photography. And that data has also been impounded and is being used in our process of trying to understand what happened.

We're also going to discuss seals. That has




been a very visible topic lately, and Mr. Mulloy of the Marshall Space Flight Center will go into a fair amount of detail on seals.

And we're looking at environmental effects. So there is a range of things that we're focusing on, Mr. Chairman, in our task force, that we will be working and interacting with you and your [335] Commission to make sure that all the data that is being generated by our task force is available to you and you understand that particular data.

And I think a point that was made earlier that I would like to just close on before I introduce Mr. Mulloy is that, you know, a lot of memos have been written about different concerns and issues in the program, and those memos, there are hundreds and thousands of those kinds of memos throughout the whole program.

Those concerns are looked at by the engineering and the technical analysts in the overall program. They are thoroughly reviewed as a part of our flight preparation process, which starts out at the contractor and then goes to the project office at a particular center that is responsible for this, and then goes up to the center management and then goes to what we call level two management at the Johnson Space




Center, which we described the other day, and then comes to my level.

So there has been a thorough look at all of those elements that are critical to the launch of a space shuttle. And I would just like to say that on the solid rocket motor we believe that has been done as well, and you will hear that from Mr. Mulloy.

And we're also going back and looking at the engines, the tank, and so forth with that same degree of thoroughness to assure that all of that has been done for those elements as well.

With that, Mr. Chairman, I would like to turn this over, if there are no questions.

CHAIRMAN ROGERS: Let's see. There may be some questions.

(No response.)

MR. MOORE: I would like to introduce Mr. Larry Mulloy, who is the project manager of the solid rocket booster at the Marshall Space Flight Center.

(Witness sworn.)


[Please note that some of the titles to the references listed below do not appear in the original text. Titles are included to identify and clarify the linked references- Chris Gamble, html editor]
336] [Ref. 2/11-1] AGENDA. [Ref. 2/11-2] STS 51-L TASK FORCE.

[337] [Ref. 2/11-3] STS 51-L TASK FORCE.

[338] [Ref. 2/11-4] STS 51-L TASK FORCE.

[339] [Ref. 2/11-5] STS 51-L TASK FORCE.


[340] 617




MR. MULLOY: Mr. Chairman, members of the Commission:

As Mr. Moore has stated, I intend to give you a briefing on some aspects of the solid rocket booster assembly, the details of that solid rocket booster, and then concentrate with a bit of information on how the solid rocket motors are assembled, how they were refurbished, and particularly on the seals and the joint.

(Viewgraph.) [Ref. 2/11-6]

The solid rocket booster is made up of a number of assemblies. The forward assemblies here are manufactured and refurbished by the United Space Boosters booster production company, and the forward skirt and forward frustum and the nose cone. That assembly contains the electronic devices and also the recovery system for the solid rocket boosters. It has three main parachutes, a drogue parachute, a pilot parachute, in that assembly, which does return the booster to the ocean, where it is retrieved by retrieval ships, brought back to the Kennedy port for disassembly, and returned to the manufacturer for refurbishment.




The aft assembly, which is known as the aft skirt, which is the hold-down point for the total shuttle system, is also manufactured and refurbished by the United Space Boosters booster [341] production company, and then the center section here is the solid rocket motor, which is the primary area of interest that we have here today.

The solid rocket motor consists of four casting segments. Each of those casting segments is about 24 feet long. The booster is 146 inches in diameter. The casting segment itself is made up of two tank segments and joined by a factory joint.

When the motors are cast at Thiokol, they are then shipped by rail car to the Kennedy Space Center, where they are assembled into the shuttle stack. This center factory joint here is covered with the insulation that is inside the motor. There is an insulation, then a liner, and then the propellant.

The end joints or the field joints are metal joints with a tang and clevis that I will describe in more detail, and sealed with two Viton O-rings. When the boosters are recovered and returned to the Kennedy Space Center and disassembled, there is a very thorough inspection done of those assemblies immediately after retrieval.




Steps are taken to preserve the hardware, as you will see in this model or this section, out of flight hardware that I will show of an actual section of the joint. The D-6 steel material is very susceptible to corrosion, so immediate steps are taken to wash down that metal and apply grease to protect the joints particularly from any corrosion.

CHAIRMAN ROGERS: Mr. Mulloy, could you as much as possible relate what you are saying to 51-L?

MR. MULLOY: Yes, sir.

CHAIRMAN ROGERS: How many retrievals were made?

MR. MULLOY: The aft segment on 51-L, the right hand booster, the aft segment had been used twice, once in a test motor and once in a flight motor. The aft center segment had been used once. We have used segments up to four times.

CHAIRMAN ROGERS: And is there data on how each segment was handled, both in retrieval and in Utah?

MR. MULLOY: Yes, sir. There is a complete record of the inspection results immediately after retrieval. Then when the booster segments are returned by rail car to the Wasatch Division of Morton Thiokol, there is - the process that goes through is a washout, initial washout




of the remaining insulation material, then a grit blast, and the amount of material removed with that grit blast to take the paint and remaining insulation off is measured and recorded.

There is a detailed inspection then made for cracks, surface blemishes, and dimensional tolerances, and a structural analysis made to assure that that is acceptable. Then that segment is put back into what we call a hydroproof test, where we apply 112 percent of the maximum operating pressure that that segment has to sustain in the next flight.

Subsequent to that hydroproof test then there is what is called a magnetic particle inspection made of the case segment, to assure that there aren't any flaws that are not visible to the naked eye. And then that segment is put back through processing.

One of the critical things in the acceptance of that segment is a dimensional check to assure that particularly the mating joint, the tang on one end and the clevis on the other, is within the dimensional tolerances for new hardware. Reused hardware has no different tolerances than new hardware.

We do have a procedure whereas a hardware that doesn't precisely meet the drawing specification can be dispositioned by material review boards or a waiver can



[342] 621


be issued. One of the things that is being investigated, of course, for 51-L is if any of those things applied to any of the segments on the 51-L vehicle.

To my knowledge, all of the hardware in the solid rocket motor on 51-L met all of the requirements for new hardware.

DR. RIDE: Have you ever recovered any of the solid segments that didn't meet the criteria for reuse?

MR. MULLOY: I believe in STS-1, either 1 or 2 - and perhaps Bill Lucas may remember - there was one segment, due to the splashdown loads and cavity collapse loads - I would point out that there are stiffeners. These rings that you see back here on the aft segment are stiffener stubs; I believe my recollection is that we added an additional stiffener into the segment to preclude the loss of the aft segment.

And I do believe that in the early flights one or two segments had gotten outside of dimensional tolerances and could not be reused.

Since STS-5, which is when I took over the program, we have had no loss of segments due to flight loads or splashdown loads.

DR. RIDE: Do you X-ray any of those segments?

MR. MULLOY: Yes. The segments are X-rayed in




Utah. In the initial stages of the program, there was 100 percent X-ray, 100 percent to the extent that you can get to 100 percent X-ray of a large structure like this. The maximum possible X-ray was done on all of the development qualification motors, and through a period up through the first six flight sets, to assure that our process that we had in place was producing a repeatable product.

We never found any problems as a result of X-ray, and what we are doing right now is a periodic X-ray to assure that the process controls that we have in place for the propellant, liner, and insulation, that we're not getting outside our experience on that.

And so essentially, what we're doing right now is X-raying about one segment a month on a sampling basis.

VICE CHAIRMAN ARMSTRONG: Anything other than X-ray? Ultrasound or NMR or other approaches used?

MR. MULLOY: Yes, ultrasound is used, and visual inspections, particularly visual inspections of the end of the segments, where you can determine whether there is any de-bond of the insulation to the liner or the insulation to the case wall.

DR. RIDE: What percentage of the segments is




one segment per month?

MR. MULLOY: Well, of course, at the rate we've been going now, at a rate of 12 per year, we are casting eight segments per month, and so it is one of eight, essentially.

MR. WALKER: Have you X-rayed any recovered segments?

MR. MULLOY: No, there has been no X-ray of the recovered segments. There is nothing there but the steel. We do not do an X-ray of the steel. We do a surface dye penetrant inspection of that steel segment and a proof test.

CHAIRMAN ROGERS: So you will have a history, a full history of these two booster rockets that were on 51-L?

MR. MULLOY: Yes, sir.

[343] CHAIRMAN ROGERS: Has there been anything that's come to your attention that was unusual about the two boosters on 51-L?

MR. MULLOY: No, sir. In going through - and I will cover the readiness review process that we went through - there is nothing that is in any of the records that I have reviewed that is unique about the boosters on 51-L.

DR. RIDE: What kind of effect would you




expect from the corrosion on particularly the O-rings and the putty? I guess what I'm interested in is, if you recover the solids from 51-L do you expect to learn anything about the O-rings and the putty and the joint, or do you expect corrosion?

MR. MULLOY: What we are particularly interested in - and perhaps I should get into the details on the joint here. From a corrosion aspect, the primary concern for corrosion - and let me turn this in the flight direction here. The primary concern for corrosion is in the sealing surfaces of where the O-rings, which are these two black 280 thousandths diameter devices you see in these grooves here.

We are particularly concerned for pitting that may be inside of that sealing surface, because a pit obviously can provide a path for hot gas to get by the O-ring.

CHAIRMAN ROGERS: Could you describe what you're holding?

MR. MULLOY: Yes, sir. What we have here is a section from an actual solid rocket motor. The bottom section is the upper portion of one of the casting segments. The black on the inside is the propellant insulation.

The piece on the top is what is called the




tang end of a motor segment. This is the field joint. It also is the factory joint, case to case. As I mentioned, two of these 12-foot segments go together to make one casting segment, and that is what goes to Kennedy for assembly.

On the factory joint, there is no discontinuity in this insulation, because the insulation is applied after the joint is made. So you have insulation over this joint.

On the field joint, however, there is this discontinuity in the insulation, since you have to put it together at KSC, at the Kennedy Space Center. And this gap between the insulation is filled with a zinc chromate asbestos-filled putty. That putty is laid up in strips prior to assembly.

We use strips of putty that are eighth inch and quarter inch thick and an inch to an inch and a half wide, to lay that putty up in a precise drawing pattern such that we are sure that the putty, when laid into this joint, does not extrude outward, but you have a good fill of the putty between the insulation surfaces, but that it does not extrude down into the O-ring gap such that it would tend to unseat the O-ring.

These O-rings in here are Viton rubber, provided by Parker Seals, and they are, as I say, about




280 thousandths in diameter, and there are two of these at each one of the joints on the vehicle. The assembly is done in this position, with the tang end up and - excuse me, with the clevis end up and the tang end down.

Looking on this side, you see a pin that is a one-inch pin that is a high strength steel, that there are 177 of those pins in a joint. That provides the structural integrity of the joint.

You also see what looks like a little clip here on the outboard leg of the clevis. That is a 32 to 36 thousandths of an inch shim. The purpose of that shim is to assure that we have a [344] controlled dimension on the outer leg of the tang to - the outer leg of the clevis to the tang, to maximize the O-ring compression or the squeeze on these O-rings between this inboard tang, the inboard leg of the clevis and the tang.

MR. HOTZ: When do you get that squeeze?

MR. MULLOY: On assembly.

MR. HOTZ: You don't get it during launch?


MR. HOTZ: Do you get it during launch?

MR. MULLOY: Yes, sir. The design is to assure that you maintain launch, such that, the way these seals operate is it is a




that compression during pressure-actuated seal, that you want compression on the seal such that when the motor pressure is applied to the seal that the seal will extrude into the gap downstream of the pressure and provide the pressure seal.

MR. HOTZ: Is there any particular phase of launch when that pressure is the strongest?

MR. MULLOY: Yes, sir. We go from zero up to the maximum pressure in about 900 milliseconds, and so it is instantaneous. And then we hold that max pressure for 20 seconds. And I will show you a pressure profile later in the briefing.

And then that pressure drops down to about 600 psi, and then it ramps back up slightly, and then you go into the thrust tailoff at approximately two minutes into the flight. And I do have a profile of that in the briefing.

DR. RIDE: Could you describe the corrosion on the joint?

MR. MULLOY: Yes. You can see the corrosion. What it amounts to is pitting in the metal, and so you see the corrosion that is on the outside of this piece here, is what we don't want to have inside the O-ring groove. That is why we take extra precaution to assure that we immediately preserve that hardware, because when we get it back it has been in the sea water




for perhaps 30 hours longer with rough sea.

DR. RIDE: What about corrosion of the putty and O-ring? Is that a problem?

MR. MULLOY: Corrosion? Extrusion of the putty?

DR. RIDE: No, I think what I really want to know is how does the sea water affect the O-ring and the putty. "Corrosion" is the wrong word, but do you expect to find the O-ring intact when it has been in the sea water for a long time?

MR. MULLOY: Oh, yes. And we also find the putty intact. And as we have shown you in the data that we have presented to the Commission, where we have all of the data about our experience with this joint post-flight, you can clearly see the putty is still there in the joint. You can clearly see hot gas paths through the putty, and you can see very clearly any erosion that has occurred to the primary O-ring, and that is definitely attributed to the flight motor operation and not any effects of sea water.

DR. FEYNMAN: Can I ask a few questions in succession to help explain how this thing works?

MR. MULLOY: Yes, sir.

DR. FEYNMAN: This rubber thing that is put in, the so-called O-ring, that is supposed to expand to




make contact with the metal underneath so that it makes a seal, is that the idea?

[345] MR. MULLOY: Yes, sir. In the static condition it should be sealed to - it should be in direct contact with the tang and the clevis of the joint, and be squeezed 20 thousandths of an inch.

DR. FEYNMAN: And if it weren't there, if it weren't in contact at all and there was no seal at all, that would be a leak. Why don't we take the O-rings out?

MR. MULLOY: Because you would have hot gas expanding through the joint and destroy- -

DR. FEYNMAN: Pushing the putty through, and so on?

MR. MULLOY: Yes. You will always push the putty through, because the motor pressure is 900 psi nominally, 1,000 psi at max, and that putty will sustain about 200 psi.

DR. FEYNMAN: Now, we couldn't put instead of this some sort of material like lead, that when you squash it it stays? It has to be that it expands back, because there is a little bit of play in this joint and it has to be able to come back. I mean, it is a rubber material, so that it comes back when you move a little, and it stays in contact, is that right?




MR. MULLOY: Yes, sir, that is the purpose of the putty, as a thermal barrier, a thermal barrier. In the data that we have presented to the Commission, as you noted yesterday, we have looked at other alternatives, some of those alternatives are things like - -

DR. FEYNMAN: I'm talking about the rubber on the seal?

MR. MULLOY: I'm sorry?

DR. FEYNMAN: In the seal, in order to work correctly, it must be rubber, not something like lead?

MR. MULLOY: Yes, sir.

DR. FEYNMAN: Because when the seal moves a little bit when there is vibration and pressures, it would lift the lead away, which the rubber expands in place?

MR. MULLOY: Yes, sir.

DR. FEYNMAN: So it is important that it have this property of expansion and not be plastic, like lead. And I think you call that resilience, right?

MR. MULLOY: That is correct. It has to have resiliency, and that is why we use an elastomer.

DR. FEYNMAN: If this material weren't resilient for say a second or two, that would be enough to be a very dangerous situation.

MR. MULLOY: Yes, sir.




DR. FEYNMAN: Thank you.

MR. MULLOY: If it was rigid.

MR. HOTZ: Mr. Mulloy, could you tell us whether the shim that you have put in here to damp out some of the vibration is an original design consideration, or is that something you added as a result of experience?

MR. MULLOY: That was added. It has been on since the first flight vehicle. It was added as a result of experience during the early development testing on the motor. It is not for the purpose of damping vibration. It is for the purpose of assuring a uniform gap on the outside and maximum squeeze on the O-ring on the inside.

DR. COVERT: Mr. Mulloy, for purposes of my own understanding, I would like to have you go through the ignition process. And I find that I understand things best if I can feed them back to you so I want to ask a series of questions, and I will use this as an example.

This gap here is filled with the zinc chromate asbestos putty-like material.

MR. MULLOY: Yes, sir.

DR. COVERT: And it's designed to more or less be plastic?

[346] MR. MULLOY: Yes, sir.




DR. COVERT: Now, when you pressurize this side of it there is a little volume in here between the termination of the putty and where the O-ring lives, is that correct?

MR. MULLOY: Yes, sir.

DR. COVERT: And when you pressurize it, then, because the plastic is able to flow, it flows into this gap and compresses the air in that gap until the pressure is equal to the pressure in the combustion chamber, is that correct?

MR. MULLOY: That is one thing that could happen.

DR. COVERT: Don't confuse me with a lot of alternatives at this point.


DR. FEYNMAN: Why don't you put up the picture two from now, the one called "SRM No. 3."

MR. MULLOY: Would you put chart number three on, please.

(Viewgraph.) [Ref. 2/11-7]

DR. COVERT: Now, the point I want to get to at this point is that this O-ring then is subjected to the pressure that is caused by the plastic deforming and helping to fill this little cavity, and that in turn drives the O-ring into this crack in back of it. That




is called extrusion, I believe?

MR. MULLOY: Yes, sir.

DR. COVERT: And so that is the mechanical joint that carries the pressure seal, is that correct?

MR. MULLOY: That is correct.

DR. COVERT: Now, if there was a flaw of some kind, then what would happen would be, instead of the plastic deforming and coming into this, then there would be hot gas flowing in a narrow jet into that cavity, is that right?

MR. MULLOY: A flaw in the putty?

DR. COVERT: Yes, sir.

MR. MULLOY: Yes, sir, a flaw in the putty would cause a hot gas jet to impinge on the primary O-ring.

DR. COVERT: So that would in turn then, that hot gas, would be what would drive the O-ring and cause it to extrude and carry the pressure load?

MR. MULLOY: The hot gas jet erodes the O-ring, and the pressure rising in the cavity tends to seat the O-ring.

DR. COVERT: So you have sort of a redundant system, then. The way the design works out is that there is - if the putty holds, the gas compresses the O-ring and extrudes it into the gap; and if the putty




for one reason or another has a flaw in it and a little jet of gas comes in there, there is still a pressurization in there, and that causes this to be sealed?

MR. MULLOY: Yes, sir.

DR. COVERT: And the second O-ring then is a backup just for safety purposes?

MR. MULLOY: It was a backup to make the - to provide a redundant sealing capability.

DR. COVERT: Thank you very much.

MR. MULLOY: Yes, sir.

[347] MR. WALKER: I have a question about the O-ring. The manufacturer generally specifies the amount of compression on the O-ring by specifying the depth of the O-ring groove. Is the compression that you get here equal to the amount of compression recommended for O-rings of this diameter?

MR. MULLOY: Yes, sir. The minimum O-ring compression that we have here is 7.54 percent, and that is within the recommended levels.

MR. WALKER: What was the impact of adding the metal plates which you put at each place where you have a steel pin? Was that to increase the compression, or what was the exact purpose of that?

MR. MULLOY: The primary purpose is to assure




a uniformity of gap, and also then to assure that we would achieve the minimum compression by pre-shimming that to the 32 thousandths.

MR. WALKER: So are the shims placed on all 177 of the pin locations?

MR. MULLOY: Yes, sir.

MR. HOTZ: Mr. Mulloy, how are these materials, this putty and the rubber, affected by extremes of temperature, both hot and cold? Do they change their characteristics at all?

MR. MULLOY: Yes, sir, there is a change in the characteristic. As elastomers get colder, the resiliency decreases, and the ability to respond - -

MR. HOTZ: Now, the elastomers are what?

MR. MULLOY: That is the Viton O-ring.

MR. HOTZ: The rubber?

MR. MULLOY: Yes, sir.

Now, the putties are not as sensitive as the elastomers are to the temperature over the range of temperatures we operate. Of course, temperature - -

MR. HOTZ: How about moisture? Are the putties affected by moisture?

MR. MULLOY: Yes, sir. And in order to control that, we maintain the putty in a refrigerator and have limits on the time that it can be outside of




the refrigerator before the joint is mated. What we have found, especially at the Kennedy Space Center, with the putties, that they do tend to take on moisture, and as the putty gets more moisture it becomes extremely tacky and sticky, which makes it very difficult to lay into the joint and to work with.

And it can take on enough moisture such that the putty loses its ability to hold together. So we control the humidity that that putty sees prior to installation into the joint until we have the joint made up.

CHAIRMAN ROGERS: Was the putty on flight 51-L the same quality putty you used on other flights?

MR. MULLOY: Yes, sir, it is the same putty we have been using since STS-8. It is a Randolph type two putty, zinc chromate with an asbestos filler.

CHAIRMAN ROGERS: The same manufacturer?

MR. MULLOY: Yes, that is the manufacturer, Randolph. We did have a change of putty in the program because the original supplier of the putty, which was Fuller-O'Brien, went out of making this particular putty because of its asbestos content.

CHAIRMAN ROGERS: When was the change made?

MR. MULLOY: STS-8. And somebody could help me with the date on that.


[348] 637


CHAIRMAN ROGERS: How far back in terms of number of flights?

MR. MULLOY: This was the twenty-fourth, so 16 flights.

MR. HOTZ: Were you considering any further changes in the brand or the type of putty?

MR. MULLOY: Yes, sir, because asbestos products, of course, people are going out of the business of making asbestos every day. We were evaluating other putties. We were looking at a non-asbestos putty, as well as an Inmont Canada putty, which is asbestos-filled, and we have done some testing on that in some of our development motors that we have currently in test in the filament wound case program as an alternative to the Randolph putty.

But none of that has been implemented into the program yet.

CHAIRMAN ROGERS: Is there any reason why you were thinking of changing the putty, except for the asbestos problem?

MR. MULLOY: That's the only reason, sir, to have another source, not because of any concerns for the performance of the putty.

CHAIRMAN ROGERS: Then there is nothing unusual about the putty that was used in 51-L that you




want to call to the Commission's attention?

MR. MULLOY: No, sir, not that I'm aware of. As I say, we're looking at all of the records and the paper to assure that the handling of the putty was as it was supposed to be, that the joint was mated within 12 hours of the time that the putty was first removed from the storage.

MR. HOTZ: But you did have some very high moisture conditions on the pad just before launch.

MR. MULLOY: Yes, sir. But we haven't seen any indication that, with the exposure of the putty, as Sally mentioned, even to sea water, we don't see that kind of breakdown in the putty when we get the hardware back for evaluation, just even after 30 hours in the ocean.

VICE CHAIRMAN ARMSTRONG: When we go to Kennedy, will we be able to see how this putty is applied?

MR. MULLOY: Yes, sir.

DR. COVERT: Do you throw away the O-rings after each use and put new ones in?

MR. MULLOY: Yes, the O-rings are single use items. You fly new O-rings on each flight.

MR. WALKER: A fairly detailed question. On your diagram, there is a gap at the end of the inside




leg of the clevis - I mean, of the tang. The U-shaped device is - I mean at the other end, right there. Is that gap filled with putty or is that gap air, and the putty extrudes into that gap during launch, is that correct?

MR. MULLOY: That is air. And as I say, we take precautions to be sure that we hold the putty back off of here, such that during assembly the putty doesn't extrude down into the O-ring gap and unseat the O-ring. And yes, under pressure the putty tends to extrude into the gap.

It does not extrude totally into the gap, because, as I say, the putty won't sustain 1,000 psi, and in almost all instances, rather than the situation that Mr. Covert described, rather than a uniform decompression of putty, there is usually a breakthrough of the putty up at the 1,000 psi.


[349] 640


We don't see when we get it back. We see putty getting further down than it was on assembly, but we don't see it extruded all the way into the O-ring gap.

MR. ACHESON: Have you experimented with material as a substitute or alternative to putty which would tend to fill that groove under high pressure and temperature?

MR. MULLOY: Fill this groove?

MR. ACHESON: Yes, sir.

MR. MULLOY: No, sir, because that is not a desirable situation to have anything that would fill and get into the O-ring gap at all. We have experimented with materials that are alternatives to putty which is in the data that I presented to the Commission yesterday, looking at carbon mesh, wire mesh, and channels that would allow uniform pressurization of the cavity to eliminate the hot jet impingement that goes through the putty and other alternatives.

At this point, with the testing that we have done over the last year, we have concluded there is no better alternative than the putty that we are using based on the testing that we have done.

DR. RIDE: What methods do you have to verify that the putty has been laid properly? Do you have any




way of examining it after it has been laid to make sure that there are no air gaps?

MR. MULLOY: It is examined after it has been laid on, and I wish I had a diagram, but you will see it Thursday at Kennedy as to how that is laid up. But literally, what you do is you just lay these putty strips directly on the surface, and we use quarter inch strips here and then eighth inch strips, and they are laid up in a prescribed pattern. It is not an operator option to put enough putty on there to be sure you fill the gap. It is a drawing, it is controlled and it is inspected and signed off by quality inspection that the putty strips are installed in accordance with the procedure, and that procedure is to assure that the putty is laid in tightly onto the insulation and that you don't have air gaps in there.

And we have shown by tests that that provides the best thermal barrier. We have also shown when you deviate from that that the thermal barrier is compromised. So we are very, very careful about how that putty is laid up.

DR. RIDE: Have you had a chance to go back and look at the quality assurance records on 51-L and verify that those were signed off properly?

MR. MULLOY: That is in process now under Mr.




Moore's Design and Data Analysis Task Force, and that is in process, and hopefully Thursday at KSC you will be able to see some of the certification of the rereview of those records. All those records are at KSC where the assembly is made. All of them are under the control of the NASA investigative board, the interim board, and now the task force. But nothing during the assembly of 51-L where I get involved in that assembly process, if there is some requirement to deviate from the requirements that we have for the assembly, then I would get involved in that because it would require a waiver to deviate from that.

I have checked with my managers and with the contractor at Morton-Thiokol and the manager of the solid rocket motor project who works with me at NASA, and they assure me that they have no recollection of any deviations being worked in the assembly of 51-L.

GENERAL KUTYNA: Mr. Mulloy, we have had a history of some problems with these O-rings since about 1980.

[350] Could you summarize the history of the erosion problems and the blow-by and when they occurred, the conditions under which they occurred?

MR. MULLOY: Yes, I can. I think it would be useful, if I may, to proceed through the next diagram




and then move into what causes the erosion, and review - it is not in this presentation today, but to review with you the numbers of instances that we have had in a summary fashion that summarizes the detailed data that I presented to the Commission yesterday.

Next chart, please.

(Viewgraph.) [Ref. 2/11-8]

DR. WALKER: Before you leave that chart, I have one more question.

MR. MULLOY: Go back to Chart 3.

(Viewgraph.) [Ref. 2/11-7]

DR. WALKER: How wide is the gap between the insulation pieces of the two different sections where the putty goes?

MR. MULLOY: Let me get those dimensions out of the presentation from yesterday.

The gap size on the field joint varies from .01 down at this narrow section here up to .4 inches at the top, and the length of this channel right here is 3.3 inches.

DR. WALKER: So is the putty just laid into that gap, or is it worked into the gap?

MR. MULLOY: No, the putty is laid on before the joint is assembled. It is laid on to the surface here and then assembled in a very precise, precisely




controlled pattern to assure that we don't get any voids, or minimize the voids that we have in the putty.

DR. WALKER: And then it is visually inspected after the joint is made?

MR. MULLOY: Well, you can't inspect it after the joint is made. All you can see is that you have extruded the putty out of the joint which you would expect to do under the configuration that we have it in prior to the lay-up. You would expect to see this kind of a bead here. The inspection is, if you didn't see the putty coming up to here, obviously it wasn't laid up properly. But the inspection is made prior to pushing the joint together, and we have many, many tests that assure that if you lay the putty in that way and then assemble the joint, you will get a fill with minimum voids.

Let me back up one chart to talk more generally about joints.

Let me have Chart 2, please.

(Viewgraph.) [Ref. 2/11-8]

MR. MULLOY: The joint we have been talking about is represented here for these three field joints. These are the three joints where the four segments are tied together. As I mentioned, there is an identical joint in each one of these segments which is covered




with the rubber in the casting process at Thiokol. There is another joint which has erosion history on it that is not the case-to-case joint but it is the - where the nozzle is attached to the aft end of the solid rocket motor. That configuration is significantly different than the case-to-case joint.

And in the case joints we have two O-rings in series on the same bore, if you will. On the nozzle joint it has this right angle sealing surface here, and when the nozzle is inserted, and I will show you on a bigger diagram, there is an O-ring that is a face seal as well as a bore seal.

So let me go to Chart 5, please.

[351] (Viewgraph.) [Ref. 2/11-9]

MR. MULLOY: Chart 5 is a larger diagram of that nozzle-to-case joint where we have also experienced some O-ring erosion, and this shows the two O-rings, this being the face seal and this being the bore seal. Because the tolerances are somewhat tighter on this joint than we have on the case-to-case joint, this O-ring groove is somewhat wider than the O-ring groove on the case joint to assure that we can assemble this nozzle to the case without damaging that O-ring.

Now, let me move forward.

MR. ACHESON: Let me ask why the tolerances




are less tight on the field joints?

MR. MULLOY: Well, because the 146 inch diameter that has to be mated to assure that we don't have any gathering of the material when we mate the joint or puckering, there has to be somewhat more tolerance in that. This is 103 inch diameter versus 146 inch diameter.

Okay, let me go to the next chart, please, which would be Chart 5.

(Viewgraph.) [Ref. 2/11-10]



Would the television people, is it necessary to have the lights on so bright? It is really intolerably hot here.

Is there any way to turn them down a little bit?

MR. MULLOY: General Kutyna, I am going to get to your summary, if you will allow me. I would like to give a little precursor to that that I think leads in to how we dealt with those data relative to 51-L.

And as Mr. Moore has mentioned, we do have a very thorough preflight review process for the solid rocket booster. That preflight review process starts with the recovery of the hardware from the last flight,




because we are very sensitive to anything that we see on the last flight that might pose a consideration that we should have for the flight readiness of the next one. So we have had that opportunity to go back and do a detailed examination of the hardware from the previous flight prior to committing to the next one.

The key thing in our flight readiness review is that previous flight performance. We look at the ballistic performance of the motor, and then particularly any problems from the previous flight.

Now, we have not had in the solid rocket motor in terms of ascent performance, we have had no anomalies related to ascent performance in the motor. What we have seen on recovering the hardware are some things that would indicate that there are some improvements that could be made in the design to provide more margin, and the particular point of interest here is the case joints and the nozzle joints, and particularly the erosion of the O-ring seals. So we have dealt with that finding on all previous flights in the flight readiness for all subsequent flights, and 51-L was no different.

Sometimes as the flight frequency increases we are in a situation where we have something from two flights back, maybe, that is still under analysis that we, even though we were able to continue with the


[352] 648


previous flight, if that isn't closed out, we look at it even for the second flight downstream. There are several things in the SRB world that have fit in that category. One of them has been some damage that we have been getting to rate gyro assemblies just due to the splashdown and the tow back and the porpoising as we tow the boosters back. We have been trying to work that problem. That is a reuse issue.

The thing of interest here is what have we seen in the O-rings. Now, the fact is, before 51-L we hadn't seen any anomalous erosion for about a year. The O-rings had been performing very well. The last time we had seen any erosion on O-rings was the January launch the year before. But we were very sensitive to, mainly because of the activity that we've had going on in the last year to try and improve the margin in that joint, we had been very sensitive to how that was going on, and we were continuing to look very carefully at the previous flights to assure that nothing had changed in that area that would change our rationale that we had developed for continuing to fly in light of the erosion we were seeing on the O-rings.

We considered that in 51-L, and concluded, particularly since we had not seen any significant erosion in the last year, and we had no test data that




changed our rationale, the same rationale then applied for 51-L as it applied to the last year in the flight readiness review.

Then we looked very carefully at the flight performance requirements for our next flight. In the case of the solid rocket booster, those performance requirements are in terms of the ballistic performance of the motor. And we review the small motor testing that was done at Thiokol to characterize the ballistic performance of the propellant that is in this particular motor. That was done in this case.

And then we go through our complete certification and verification status, and this is where I gained my confidence that there wasn't any kind of a waiver or deviation in the assembly process of 51-L because we review all of those at that point in the flight readiness process, and none are in the record, and I am confident none were brought to my attention.

Next chart, please.

(Viewgraph.) [Ref. 2/11-11]

CHAIRMAN ROGERS: Could I say on that that the only thing you say that you have had a history of one year's success with the O-rings previous to flight 51-L.

MR. MULLOY: Yes, sir.




CHAIRMAN ROGERS: The only thing that might be different or that might affect the O-rings differently was the weather then?

MR. MULLOY: Yes, sir, and I am addressing at this point the flight readiness review process, and at that point the weather was not a factor, and I will get into the one day prior to launch consideration of the weather.

CHAIRMAN ROGERS: Okay. I think we prefer, and I don't want to disrupt your presentation, but I think we should have a full session just on weather so we can focus on it.

MR. MULLOY: Okay. There are no charts in here on that.

Okay. The levels of review. In the case of the SRB, we do require that our contractors have a flight readiness review process that covers all of that information, and that is documented. That is chaired by a Senior Vice President at Thiokol above the level of the program manager.

[353] And he uses other people at the Wasatch Division who are not on the SRM project to do that flight readiness review.

Then my element managers, I pointed out that I have essentially two contractors on this.

MR. HOTZ: Could we have his name, please?




MR. MULLOY: Yes. That would be Calvin Wiggins.

MR. HOTZ: How do you spell that?

MR. MULLOY: W-i-g-g-i-n-s. He is the Senior Vice President in charge of the Space Division at Thiokol. Thiokol is organized into three divisions, the Space Division, Tactical and Strategic. The SRM program manager works for Mr. Wiggins. The SRM program manager is Mr. Kilminster.

MR. HOTZ: How do you spell that?

MR. MULLOY: K-i-l-m-i-n-s-t-e-r.

MR. HOTZ: First name?

MR. MULLOY: Joseph.

Then my element managers then go through that same review process at a minute level of detail, and I think when the flight readiness review proceedings are presented to the Commission, you will find that there is a great deal of detail reviewed relative to the configuration and the performance predicted for the particular solid rocket motor that is going to fly.

And then I chair a review with senior managers at the Marshall Space Flight Center in the Science and Engineering Directorate there where my element managers and contractors present that to me. I am then required to review that with the manager of the Shuttle Projects




Office at Marshall, and then we have a center review with Dr. Lucas which includes all of the elements of the Marshall Space Flight Center, and that is a very thorough review. And then the level 2 National Space Transportation System manager reviews the flight readiness, still using the same agenda, the same agenda items in every one of these.

And then Mr. Moore, who is the Associate Administrator for Manned Space Flight has the level 1 review. And then one day before launch what we call now L minus 1, we used to do it L minus 2, but lately it is L minus 1, the level 1 has a review to assure launch readiness, and the purpose of that review is to assure that nothing has changed in the two weeks since they had - Mr. Moore had his level 1 flight readiness review. Any deltas that occur are then presented to that board.

I can give you one example of where nothing was presented relative to the solid rocket booster until we got to the L minus 2 day review, and that was because we were at a frequency of flight that we did not get a look at the joint between the nozzle and the case joint until after the level 1 review, and you will find in the record that at the L minus 2 day review I presented the details of our observation there and the rationale for




flight for that.

And then in the case of 51-L, up through the L minus 1 day review, no concerns regarding SRM joint O-ring erosion were expressed during any of that process.

Now, I would like to get into what the basis for that was at that time. If you will go to, ] guess it is Chart 7 - next chart, or Chart 8 - -

(Viewgraph.) [Ref. 2/11-12]

[354] MR. MULLOY: - our experience when we were looking at 51-L that we were looking at - and this is a summary of the detailed information that was provided to the Commission yesterday - our experience was that prior to 51-L we had eleven static test motors and 48 flight motors. The field and nozzle joints of those 57 motors had been examined which represent some 288 joints with 456 O-rings, and this is a summary again of the detailed data. Six of the 171 field joints exhibited some erosion of the primary O-ring.

Now, if I may, I would like to go to Chart 10 and then come back to this one.

(Viewgraph.) [Ref. 2/11-13]

MR. MULLOY: I think it is helpful when we say some erosion, what kind of mechanism we are talking about there. This is the nominal configuration I have




already shown you where we have zero pressure in the motor and we are ready for ignition. We have these two O-rings in here which are specified to have a 20/1000 inch minimum compression such that when they are called upon to do so, the primary O-ring can be extruded into this gap and form a seal.

If it did not have the compression on it, the gas - and I will show you a scenario there that does that - the gas can blow by the primary O-ring, and it will never seat. So you have to have that compression, and we are sure we have that from the dimensions of the clevis and the tang in the steel, and assuming a minimum O-ring with - and some compression set in that O-ring, to account for the resiliencies that it has to follow the metal as it expands.

Now, as the motor is pressurized, and if I may take that down for a moment and bring up Chart 9 - -

(Viewgraph.) [Ref. 2/11-14]




MR. MULLOY: - this is a typical pressure time trace. Full pressurization of the motor from time zero occurs in 600 milliseconds, .6 second. And then we are up here at the maximum pressure, operating pressure, nominally 900. It is qualified for 1004, but 900 is the nominal operating pressure, and we stay there for about 20 seconds, and then we have a thrust tail-off to limit the G forces on the Shuttle vehicle to 3 Gs, and this thrust profile is designed to do that in conjunction with the throttling of the engines to such that we don't exceed a 3 G load on the vehicle.

And then at about 50 to 60 seconds, we start ramping back up again, and that is what this bar indicates. And so there are two times in the motor operation when the motor is increasing in pressure, and that is in the first 600 milliseconds, and in the 50 to 75 second timeframe.

So what is going on in this first 600 milliseconds, if I may go back now to the previous chart, Chart 10 - -

(Viewgraph.) [Ref. 2/11-13]

MR. MULLOY: - the nominal situation, and I pointed out to you that only six of 171 have exhibited any erosion, and so the other 165 of them performed as you see in this diagram here, which is the intended function




of this joint.

Two things happen with that motor pressurization. The additional tension loads are put into the case due to the pressure. The 1000, getting up to that 1000 psi tends to want to pull this joint apart. That pulling on these pins then tends to rotate this clevis outward as you pull with tension load on the pins. The other thing that is happening is the outward pressure on the motor is tending to want to expand the motor more out here in the membrane area of the case than it is [355] in the stiffer joint section, which further tends to cause a rotation of this clevis upward, which tends to reduce the initial squeeze on the O-ring.

Well, what has happened in 165 of the 171 cases, when this O-ring was called upon to exercise itself, it did so by extruding into this primary groove. You see no erosion on the O-ring. You don't see any soot blow by the O-ring, and the secondary has not even been energized because the primary has done what it was designed to do.

Any questions about that?

MR. HOTZ: Could you describe the rotation again? I am not quite clear on that.

MR. MULLOY: Okay, sir. The motor is at zero




psi, zero pressure. We come up in 600 milliseconds to 900 psi. So there are two things that that case is wanting to do. It is wanting to expand outward due to that pressure, and it is also wanting to expand longitudinally. The longitudinal load pulling on that pin tends to want to rotate that clevis. In other words, if you can visualize, if you pulled on that long enough to fail it, the clevis would open up until the tang end pulled out of there.

The other thing that is happening is that that joint is much stiffer. It is like having a belly band, if you will, around a balloon, a belt around a balloon. Now you blow up the balloon, or say an elastic belt around the balloon. Now you blow up the balloon, the balloon will expand more where the elastic belt is than where it isn't. And so you get this exaggerated shape like that which further tends to rotate the joint.

VICE CHAIRMAN ARMSTRONG: What holds the pin in place?

MR. MULLOY: The pin is held in place by a metal strap. After all the pins are put in, there is a metal strap that is put around the pins and cinched down just like a container strap mechanism, and then that is closed out with cork. A quarter inch of cork is put around that just over, just over this section of the




clevis, and that cork is there to assure that during ascent, since the heat sink of that band is much less than the heat sink of this whole mass here, if we got any aerodynamics under that band, that band could heat up and fail, and we could lose the pins during ascent. So the cork is a thermal protection for the retaining band on the pins.

DR. WALKER: I have a couple of questions on the O-ring. There are some tolerances on the diameter of those O-rings.

Do you inspect each O-ring to see that it is within tolerance?

MR. MULLOY: Yes. The tolerance is plus 5 and minus 3, and the O-ring is inspected with a micrometer on receipt to assure that it is within tolerance.

DR. WALKER: Do you inspect it at many places along its length?

MR. MULLOY: Yes. I believe it is every two feet, and relative to 51-L, all of the O-rings that are in the inventory are being re-inspected to get a statistical data base to try and understand if possibly there could have been an undersized O-ring, for instance, in 51-L.

VICE CHAIRMAN ARMSTRONG: Is there a tolerance on this pin and these holes that isn't shown in that





MR. MULLOY: I am sure there is, Mr. Armstrong. I am not sure exactly what that is. Il not an interference fit. There is a tolerance. I can get that for you.

[356] CHAIRMAN ROGERS: Mr. Mulloy, on your O-ring history, which is a very useful review, I think, for our purposes, would you mind taking each one of these observations and just making some comment on them? For example, you say that you examined 228 joints with 456 O-rings. The first observation is 6 out of 171 exhibit some erosion of the primary O-ring.

MR. MULLOY: Yes, sir.

CHAIRMAN ROGERS: That did not disturb you, I suppose? You would like to correct it, but it wasn't, in and of itself, it didn't disturb you too much?

MR. MULLOY: It wasn't disturbing from a standpoint of safety because the O-ring, even though it was eroded, had done what it was designed to do. It was disturbing from the standpoint that we were looking for ways to increase the margin such that we wouldn't even have that incidence of erosion.

CHAIRMAN ROGERS: Going to the second, you say that two of those joints, there was some soot behind the primary O-ring.




Was that a serious problem, and if so, what was the problem?

MR. MULLOY: That is more disturbing than just having the O-ring erosion and then the joints or the O-ring then seated, although this, too, is in the population of the six. The six with erosion, two of the six with erosion showed soot. The concern there is that there is some blow by the primary which says that we are concerned that we have adequate squeeze on that primary such that we won't get that blow-by, and it will energize and go into, extrude into the gap without blow-by.

And yes, that is where we started looking at things like how can we decrease the joint rotation.

CHAIRMAN ROGERS: And were those instances just prior to 51-L or a long while back?

MR. MULLOY: No, sir. As I said, there were no instances of that for a year before 51-L.

CHAIRMAN ROGERS: On the next one, 16 of the 57 nozzle joints exhibited some erosion of the primary O-rings. How did that relate in terms of concern to the other two? Was that more serious or less serious or about the same?

MR. MULLOY: It is about the same. There is




more concern for the case-to-case joints because of that rotation. In the case of or in the instance of the nozzle-to-case joint, we don't have that same rotation of the joint. So we deemed that fixing, improving the margin in the case joints by reducing the rotation to put it in the same population as the nozzle joint would be a desirable improvement.

CHAIRMAN ROGERS: The next one refers to soot in the nozzle joints, eight out of 57, and would the answer be the same?

MR. MULLOY: Yes, sir.

CHAIRMAN ROGERS: And then you have one nozzle joint secondary O-ring which has been eroded. Was that of particular significance?

MR. MULLOY: Yes, sir, it was because until we saw that, we were always assured that even though we were causing some initial damage to the primary O-ring, that the primary O-ring was functioning. In the instance of that nozzle joint, we were now seeing a violation of the secondary seal, and we did after that, and before we would commit to another flight, we went and did some extensive testing of the tolerance to that, and did an analysis that matched that testing so we could determine what the limiting mechanism was, in other words, how long, if you - since the size of that cavity behind the


[357] 662


primary O-ring is of limited volume and you are pressurizing that cavity with a very large volume of gas, which is inside the solid rocket motor, there is a limit of time that that gas can flow into that cavity.

Once the gas flows into that cavity and the pressure becomes the same as in the motor, flow stops. So our rationale was through testing, can we get enough damage to the secondary O-ring before the flow stops such that we would have a failure of the secondary O-ring? And our analysis and our tests which the analysis correlated very well with, said that we had a margin of three - we could take three times what the maximum amount of erosion that we had observed and have a margin of two on what was theoretically probable under the limited time that that flow could occur. And thus, we concluded that that was an acceptable situation.

We have not had any other secondary O-ring erosion on any joints since that instance.

CHAIRMAN ROGERS: So you were satisfied based on that experience that you did not have a problem with 51-L in that connection?

MR. MULLOY: In that connection, yes, sir.

MR. ACHESON: If soot blows by the primary seal, will it lodge between the secondary seal and the wall of the chamber to prevent a tight squeeze?




MR. MULLOY: No, sir. We haven't seen that. What we tend to see is that that soot is very, very fine. It is the products of grease, the pyrolysis of the grease and some pyrolysis probably of the O-ring itself, the primary O-ring, and it is a powder, and blowing - it would have to blow by the secondary before it could compromise that, and we have seen no evidence of that at all.

You see a kind of a fan-shaped sooty spot in the putty, if you will, impinging but not into the groove generally. You will see that in the primary groove, but you do not see it in the secondary groove.

DR. WALKER: A question on the six incidences of erosion of the primary O-ring in the field joints.

Was each of those associated with some channel or damage to the putty?

MR. MULLOY: Yes, sir. There is a track through the putty to that erosion.

DR. COVERT: Mr. Mulloy, on the six rings that exhibited some erosion, do you have numbers comparable with those on the nozzle joint erosion? In other words, you eroded half of those needed or what?

MR. MULLOY: Yes, sir. Theoretically we have a factor of two, based upon tests and analysis, over the maximum observed.




MR. FEYNMAN: Sir, you suggested that if the primary O-ring were to fail, it is still no big problem because the secondary O-ring might hold.

MR. MULLOY: Yes, sir, it should energize.

MR. FEYNMAN: But there is a way for the gas to come out, at least possibly, and that is the leak test port that you put in to make a pressure to test the O-rings, and I wonder how good we can expect - how was it sealed? How was it closed, and how good is it? Can we guarantee that that might not fail, that is, the gas come out through the hole that you used to put the pressure on to test the O-rings to see if they were okay earlier on?

MR. MULLOY: Yes, sir, that is installed to a torque requirement and inspected and signed off. It is installed to that torque requirement, and then there is extensive test data that indicate [358] with that test plug, and it has the O-ring sealing surface also at that torque, will not leak at 1000 psi.

But if a human error was made and the test port plug was left out, obviously - and you went by the primary seal, that would be a leak source, or if it wasn't properly torqued, there could be a leak source through there which could lead to failure of the secondary O-ring.




CHAIRMAN ROGERS: How many checks of human failures do you make? In other words, if one person - do you have to rely on the one person's activity, or does somebody supervise that one person? How many checks do you make to avoid that kind of human failure?

MR. MULLOY: Well, the first check is the technician who makes the installation. The second check is by the contractor, quality inspection, of whoever is making that installation, and then there is a government inspection check on that.

CHAIRMAN ROGERS: Who makes that? Who is the government?

MR. MULLOY: In the instance of the leak check port, for instance, that is Air Force Quality at KSC.

CHAIRMAN ROGERS: Yesterday we talked about the orientation of the leak ports on the two solid boosters. Since we have a model here, could you indicate where those were?

MR. MULLOY: Yes, sir. On 51-L, on the right hand booster, it is located on this axis, and on the left hand booster it is located on the other axis.

MR. HOTZ: Mr. Mulloy, while you are at the model, could you indicate and describe for us the pressures on the solid rocket boosters that are caused by the so-called Twang maneuver just before launch?

MR. MULLOY: Yes, sir.




The main engines ignite approximately 6 seconds before the solids ignite. That timing is set such that when the main engines ignite, and the Shuttle stack is bent over, the hold-down point for the whole stack is here on four points at the bottom of the aft skirt on the solid rocket booster. That is restrained. So there is a bending in this direction.

So the stresses that are put on are bent - it is a bending moment.

MR. HOTZ: They are bending forward in the same direction as the Shuttle?

MR. MULLOY: Yes, in this direction because the only thing that is applying force are the main engines over here, which is an eccentric kind of a load, which tends to rotate it this way. And then the timing of the ignition of the boosters is timed such that you are back in the vertical position at ignition.

MR. HOTZ: Have you any measurement of the quantity of the force that is put on the SRB?

MR. MULLOY: Yes, sir. That was done in the facility verification vehicle early. There was a stack made, and then there was what was called a Twang test and a deflection test that was run on the boosters where they were deflected for the maximum predicted amount and the strains measured, and that is accounted for in the





In other words, they were actually pulled over from this forward - -

MR. HOTZ: What was that maximum predicted amount, do you recall?

MR. MULLOY: The deflection?

MR. HOTZ: Yes, sir.

[359] MR. MULLOY: No, sir, I don't recall what that is at the tip. It is very visible in watching launches.

MR. HOTZ: Thank you.

DR. RIDE: Have you - when you have gone back and inspected the O-rings that have experienced erosion, have you seen the erosion occur at the same point circumferentially on the different O-rings?

MR. MULLOY: No. In the data that I presented to you yesterday, you will see on the field joint that there is no preferred location on the case field joints, and those six occasions, you find that scattered over all 360 degrees of the circumference, and the same is true in the nozzle-to-case joint. There is no preferred location. It seems to be random in circumference, more related to the point, I think, where the pressure breaks through the putty as opposed to any loads or gap dimensions in the joint.

CHAIRMAN ROGERS: Mr. Mulloy, just to clarify for the record, the material you presented to us yesterday is not any different than the material you are presenting today, is it?

MR. MULLOY: No, sir. What I have done today is on that one chart that we are dealing with here is summarize the details of all of those detailed observations by flight number, degree of erosion, location of the soot around the azimuth, etc.

DR. WALKER: A couple of times you referred to the vacuum grease that you use on the O-ring.

Is that silicone grease, and could you explain the purpose?

MR. MULLOY: That is an HD-2 grease, and it is not silicone.

DR. WALKER: What is the purpose of putting grease on the O-ring?

MR. MULLOY: The purpose of putting grease on the O-ring is to ease the installation of the O-ring into the joint and assure that you don't damage it. The purpose of having the grease in the joint is to keep the D-6 from getting into the condition that that sample is in.

Are there any further questions on this particular chart?





MR. MULLOY: Okay, sir.

Let me move forward to some other conditions of primary O-ring erosion.




MR. ACHESON: In the examinations of either the test segments or the flight segments, have you ever found test port damage?

MR. MULLOY: No, sir, no evidence of any heat damage through a test port.

DR. RIDE: What does the plug on the test port look like?

MR. MULLOY: It is a cad-plated steel, oh, about a quarter inch in diameter, and then it has - it looks like a screw, and it has - on the head it has an O-ring. Let's go to chart 11.

(Viewgraph.) [Ref. 2/11-15]

Continuing with the physical explanation of what we have seen, this is a case where we see two of the six that did erode on the primary. We show soot passed the primary O-ring with no damage to the secondary O-ring, and that soot we're talking about is in this area here, between where you see the two O-rings on this diagram.

What is happening there is the pressure rises from about zero to 200 psi, on its way to 900 psi. We have a concentrated hot gas jet through the putty that impinges on that primary O-ring [360] and begins to erode it while it is being transported to its seated position. While it is being transported, then there is some




blow-by, and that is where you see the soot deposit, and then the O-ring extrudes into the gap and the erosion continues for a short time and then stops, and the pressure rises to operating pressure and the primary O-ring remains fully seated, and erosion on the primary O-ring stops at that time.


And that has been observed. We have had the erosion on the six of the 171, and that is the mechanism by which you can have erosion on the primary, the primary seats, but you still see soot behind the primary, because that soot is being blown by in the seating process and extruding into the gap.

(Viewgraph.) [Ref. 2/11-16]

Chart number 12 is a case where we see soot without any erosion. There is a deposit of soot behind the primary O-ring, but there is no observable erosion on the O-ring, as we reported. And that happens very early in the ignition transient from zero to 50 psi, where you have the blowby.

But it is of such short duration, in that first few milliseconds, that no erosion occurs to the primary O-ring, and it then extrudes into the gap and seals. So that is a configuration that goes with that observation.

And so all of these are what we expect the




joint to do, primary O-ring sealing. Now, what we have not seen on any of the 171 joints examined is what I will show on chart 13.

(Viewgraph.) [Ref. 2/11-17]

Which, as we're going from zero to 200 psi on the way to 900 psi, the primary O-ring does not seal. The secondary seal is energized and seals, because all of the pressure now is on the secondary seal, and it does what it is supposed to do.

It extrudes into the gap. The pressure rises on up to operating pressure, and during that blow-by of the primary seal, primary erosion occurs, and erosion of the secondary occurs, but it does not compromise the integrity of the seal. On any of the hardware we have examined, we have never seen that condition.

VICE CHAIRMAN ARMSTRONG: How can you tell that, because the primary seal is essentially intact?

MR. MULLOY: No, sir. Because the secondary seal is not eroded. That is a condition where the secondary O-ring erosion occurs, and we have never seen that on a case to case joint.

MR. ACHESON: Does erosion depend upon blow-by, or can you have erosion just because it is in the presence of the heat and the pressure without





MR. MULLOY: That first case that I showed, six of them, that is that case. There is no blow-by, there is erosion, but no indication of blow-by of the secondary seal or the primary seal. That says that you've got compression on the O-ring. As the pressure hits it, nothing gets by it, just due to the compression on the O-ring.

The O-ring is - there is a period of time, though, that a jet is impinging on that O-ring, until such time as the cavity between the putty and the O-ring reaches motor pressure, flow stagnates and there is no further flow and no further erosion.

[361] That is the highest incidence of what we have seen, erosion without blow-by. This is just something, Mr. Armstrong, that I'm saying can happen with this design, but it hasn't.

Okay, if we could go to chart 14.

(Viewgraph.) [Ref. 2/11-18]

Now, this is a case of a failure of the joint, which on any of the 171 joints we have examined we have not seen. The motor pressure rises from zero to 200 psi, the primary O-ring does not seal, it doesn't have sufficient compression to seal. The joint rotates during the pressurization cycle and the O-ring squeeze




is lost on both of these O-rings.

As we go up to the maximum predicted operating pressure or, in the case of 51-L, 900 psi, the secondary O-ring seal does not seal, and we have hot gas blow-by and we have eroded the seals where they are no longer capable of sealing in the rotated condition, the hot gas blows by and exits through the joint.

As I say, we have seen certainly no evidence of that on anything we have examined to date.

Okay, if I might go to the next chart, please.

(Viewgraph.) [Ref. 2/11-19]

I have taken you through kind of our flight readiness review process and our rationale for accepting the conditions and tried to explain with some sketches the configuration that matches the observations that we have had. We have understood that condition for some time, and our rationale for accepting that is, as shown here, the jet impingement erosion has been shown by test and analysis to be within acceptable limits.

The analysis that is done is gas flow, heat transfer analysis, and structural analysis, by tests of full-scale motors, sub-scale motors, and a test that we did of O-rings that were damaged to the extent that it was two to three times, between two and three times the




maximum observed erosion, and two times greater than is what is predicted can occur with the time that flow can exist.

And we subjected that to 3,000 psi, which is three times the maximum expected operating pressure, and we had successful sealing with the O-rings in numerous tests. That is not a single data point.

And the other thing that leads us to accept that is that the detailed post-flight inspection that we have been doing, the very detailed analysis of those results and the tests run, to understand the limiting mechanism that does exist in that, assures understanding of those observations and a logical engineering judgment that the safety is not compromised by what we have observed.

The next chart, please.

(Viewgraph.) [Ref. 2/11-20]

In summary, I have discussed for you primarily the case joint, because that is the expressed area of interest, and the data and design analysis task force has not concluded that the failure that we have discussed here or the scenarios that I have discussed here is the cause of the 51-L incident.

However, the joint also has not been eliminated as a cause or as a factor in the accident.


[362] 676


and of course the media and all of us have seen the film that shows the plume coming from the side of the solid rocket motor. But we have not yet determined whether this is a cause or an effect.

GENERAL KUTYNA: Mr. Mulloy, might I ask, what further tests will you do in this area to determine whether it is a cause or an effect?

MR. MULLOY: The testing that is going on now is primarily aimed at understanding the behavior of this joint and the O-rings under the specific conditions of the 51-L launch, particularly the temperature, the humidity environment, the loads, and all other factors associated with 51-L.

And there is extensive testing and analysis going on now in this area, as well as other, as Mr. Moore mentioned, in the other areas of the investigation as a potential cause.

GENERAL KUTYNA: When might we see some results of these tests?

MR. MULLOY: I think you will see some of this on Thursday.

MR. HOTZ: Have you been able to analyze any further exactly where that flame first started on the casing?

MR. MULLOY: No, sir. I have looked at the




film many times, and we know that the flame is in the vicinity of this attach point in this quadrant here. But in what I have seen we have not been able to pinpoint the location of that at this time.

MR. WALKER: How far away is the attach point from the nearest joint?

MR. MULLOY: About 12 inches, I think. Yes, about 12 inches above this ring that you see here, which is the ET attach ring, and the joint is approximately 12 inches.

MR. WALKER: The joint is above the ring?

MR. MULLOY: Yes, sir. The ET attach is part of the aft segment.

MR. ACHESON: Can you show us on the model where the test port would be located?

MR. MULLOY: Yes, sir. In the joint on the right-hand side - is this the right-hand? No.

On the left-hand side, it is on the plus Z axis, which is the crew heads-up position of the orbiter; on the right-hand side, it is at the zero degree position on the minus Z, and they all line up.

CHAIRMAN ROGERS: Any other questions for Mr. Mulloy?

(No response.)

CHAIRMAN ROGERS: If not, I would like to ask




one or two questions.

Have - as you know, the press has reported a letter, the contents of a letter dated July 23rd, 1985, written by Mr. Cook to Mr. Mann. Prior to the accident, had you seen that letter?

MR. MULLOY: No, sir.

CHAIRMAN ROGERS: You have seen it now, I presume?

MR. MULLOY: Yes, sir.

CHAIRMAN ROGERS: Is your assessment that you've given us this morning affected in any way by the letter? Has it changed your views at all?

MR. MULLOY: No, sir.

CHAIRMAN ROGERS: Mr. Cook is here and we are going to ask him to testify and give his comments, and he can refer to anything he'd like to. I would like to suggest that you listen to [363] what he has to say and then we, if you would like, after that some time this afternoon, to make further comments about that letter and anything he may say.

We want to give him the opportunity to appear and for the Commission to consider his thoughts, particularly because of the visibility that resulted from the New York Times story, and to have you and anybody else that you want comment upon the contents of




that letter.

Is that okay with you?

MR. MULLOY: Yes, sir.

CHAIRMAN ROGERS: Then why don't we have a ten minute recess and reconvene after the recess.


CHAIRMAN ROGERS: Could we ask the Commission to reconvene, please.

Before we start with Mr. Cook, Dr. Feynman has one or two comments he would like to make. Dr. Feynman.

DR. FEYNMAN: This is a comment for Mr. Mulloy. I took this stuff that I got out of your seal and I put it in ice water, and I discovered that when you put some pressure on it for a while and then undo it it doesn't stretch back. It stays the same dimension. In other words, for a few seconds at least and more seconds than that, there is no resilience in this particular material when it is at a temperature of 32 degrees.

I believe that has some significance for our problem.

CHAIRMAN ROGERS: That is a matter we will consider, of course, at length in the session that we will hold on the weather, and I think it is an important




point, which I'm sure Mr. Mulloy acknowledges and will comment on in a further session.

Now, if I may and if there are no further comments, I would like to ask Mr. Cook to come forward.

(Witness sworn.)


[Please note that some of the titles to the references listed below do not appear in the original text. Titles are included to identify and clarify the linked references- Chris Gamble, html editor]
364] [Ref. 2/11-6] SOLID ROCKET BOOSTER- SRB [Sketch of SRB elements].

[365] [Ref. 2/11-7] SRM-HPM FIELD JOINT.

[366] [Ref. 2/11-8] Space Shuttle SRM Joints.

[367] [Ref. 2/11-9] Space Shuttle SRM Segment Joint.



[370] [Ref. 2/11-12] O-RING HISTORY. [Ref. 2/11-13] SRM FIELD JOINT.

[371] [Ref. 2/11-14] SRM-15A Headend Pressure (Actual Versus Predicted) at 60° F-1 Sample Per Second Data.

[372] [Ref. 2/11-15] PRIMARY O-RING EROSION.




[376] [Ref. 2/11-20] SUMMARY.




CHAIRMAN ROGERS: Mr. Cook, the Commission asked you to appear today because of recent stories concerning particularly a memorandum which you wrote on the 23rd of July, 1985, and we will let you make whatever comments you would like to make on that memorandum. And we will of course make the memorandum available to the press. IRt

(Viewgraph.) [Ref. 2/11-21]

You told me before the meeting was reconvened that you would like to make some preliminary comments, and of course you may go right ahead and say anything you would like to.

MR. COOK: Thank you, sir.

All I wanted to do really was just give a little bit of background about my own background, what I do at NASA, and set kind of a context for this particular memo that we have here. By background, I have been a program policy analyst for the federal government.

I started working for the government in 1970. I worked at the Civil Service Commission and the Food and Drug Administration. I worked at the White House Consumer Affairs Council for both the Carter and Reagan Administrations.

Then I went out of the government. I got my


[378] 682


introduction to this kind of high tech hardware when I was working on a project at TRW, on a defense intelligence hardware project, immediately before I came to NASA.

And I was brought to NASA as the resource analyst in the Comptroller's Office, and it is divided up by hardware and the hardware I was given to work on was the external tank, the solid rocket boosters, and the Centaur upper stage, which is now part of the shuttle configuration.

The memorandum in question I wrote very soon after my arrival at NASA. It was one of the first assignments that I was given, to do a little background on this. And the reason that we do things like this is because we have to prepare the budget for NASA. We have to cost out what things are going to require, particularly if we have engineering questions that come up that are going to require some kind of additional funding or some kind of change in the funding profile, to be able to pay for it.

So for this reason, we have to keep pretty much in touch with the project people in the Office of Space Flight, and we also go on field trips down to Marshall or Kennedy or other places, to try to keep as informed as we can. And then when issues arise that




look like they might be budget threats, we have got to report back on it and try to come up with some kind of estimate with the program office of what it's going to cost to repair this type of thing.

When I first got the assignment, now, I did go over it and I did talk to the people over there, the engineers over in the Office of Space Flight, who are an extremely cooperative group of people and very helpful in this type of thing.

And it became apparent to me that there were some real concerns with the O-ring problem at that time, concerns from an engineering standpoint which, as I understood it from what I discussed with people had flight safety implications and potentially major budgetary concerns, because with something like this, as I understood it, if you fix something like this you've got quite a range of cost implications.

If it is something simple, you might be able to absorb it in your budget. If it is a major redesign or re-engineering, where you've got to retrofit or you've got to go out to the contractor and have him cast new SRB segments or something like that, you might have a major budgetary hit and you have got to come up with the money.

And at that time the SRB budget on




development, the development side was pretty much winding up. SRB development was coming to a close. We had a few things that were still in the budget and had to be covered, but as far as major budgetary concerns, if something came along we would have to think real hard, work with the Office of Space Flight on figuring out how to cover something like that.

And we felt that the O-ring problem - and I think it was our impression from the Office of Space Flight - was a potentially major budget hit. When we went through the monthly briefings over at the Office of Space Flight, the O-ring problem was one of the - there was a list of budget threats that was printed each month.

Every month the O-ring problem or O-ring charring problem was on that list. Sometimes it was first on the list, sometimes it wasn't. But I don't think that necessarily reflected priority. But there was no question that the O-ring problem was considered a potential budget threat month after month from the summer and on into the fall.

[379] And I understand it was, even when it went up to the Administrator in August with the annual budget review to the Administrator, it was also listed on that presentation as a budget threat.




I reported back to my management monthly on the assessment I was getting from across the street on what the O-ring situation was. And I know, I'm not an engineer. I can't talk in engineering detail. I think I understand the basics of the joint configuration and all of that stuff, although I certainly couldn't comment on an engineer's analysis of it. But there were some things that were being factored into my analyses that I think have some bearing on this.

For instance, it was mentioned that an effort was going to be made to keep the secondary O-ring from unseating in flight or at least from breaking the seal in flight. Now, the secondary O-ring, as I understand it, we went back a couple, three years, when they first started to discover that this rotation, this joint rotation, was unseating the secondary O-ring, and that was reducing or eliminating in some cases the redundancy feature on that joint.

And so there was a lot of concern about how we could get redundancy back in that joint without having to throw away half a million dollar SRB segments and starting all over again with redesigning and recasting them. There was a 13 month lead time if you wanted to order a new segment from the manufacturer, and so if you had to throw this stuff out you had a problem.




And so we were looking for ways to get the thing taken care of in a reasonable manner. And as I understand it, the capture feature was going to be on the QM-5 firing, which had been scheduled this week, but I think has been postponed. And it was my understanding - and this is just what I gather; I have it in my documentation, I think, somewhere, but you would have to check with the program people. As I understand it, if the O-ring - the capture feature got through the review, the QM-5 firing, and whatever other reviews Marshall and the Office of Space Flight were going to do, we were going to try to get that on the booster segments around January of 1987.

But again, that was my understanding, and that would be something that you would have to check on.




There was another issue that came up on the leak test port. It was my understanding that the leak test port had been mentioned as a problem back when the redundancy requirement was reviewed for the unseating of the secondary O-ring, because at that time, as I understand it, there was no good test for checking the pressure on it once you plugged that thing back in down at Kennedy.

Now that may be something you just have to check. I cannot vouch for that talking to anybody recently. It was just another related problem they were trying to solve, the redundancy issue on that field joint.

Now I do have one question, and I'm certainly not competent at all to comment on Mr. Mulloy's presentation this morning. I won't even attempt to do that. But from my own perspective as the guy who is supposed to be watching this issue for the Comptroller's office, it was my understanding that there was at least some erosion going on in 1985 in the O-rings.

I understand, I have been told there is a Thiokol document from August 19 that documents it. I know I have seen in my own files a report from Code M indicating some erosion on a flight, I believe in August. Now the document I believe I'm referring to is


[380] 688


in September, and I would have to go back and check that.

But I would urge the Commission to work from - if you want to analyze my report, the thing to work from is probably the monthly reports of the Propulsion Division to the Administrator made every month, where it lists the propulsion issues and it lists sometimes the specific findings from the various flights. To me that was a very helpful document in kind of keeping track of what was going on.

And since I'm working from essentially secondary documents - you know, I was never in on the primary observation of this stuff or the analysis - to really analyze my document I would say you should go to the Propulsion Division, look at their documentation and their engineering staff.

But I must say that I take full responsibility for what I said in my memo of last summer. I realize that what I was saying in there was of some concern. I felt it my obligation to report to my management, and I understand my reports went all the way up to Mr. Newman, as they should have, and I felt I was being as fair as I could to present a balanced view based upon what I had been told.

So that is just kind of my introduction. Now




I would be glad to answer any questions about it.

CHAIRMAN ROGERS: Thank you, Mr. Cook.

I would like to ask a few questions. First, your memorandum was sent to Mr. Mann. He was your superior?

MR. COOK: Yes, sir.

CHAIRMAN ROGERS: And your focus of attention was primarily budgetary; is that cor-rect?

MR. COOK: Yes, sir.

CHAIRMAN ROGERS: And, to summarize it, you were, I gather, thinking about whether if changes were required for safety reasons or any other reason you had to think about how much it would cost?

MR. COOK: Yes.

CHAIRMAN ROGERS: And therefore your questioning of people in NASA was in connection with that budgetary matter?

MR. COOK: Exactly.

CHAIRMAN ROGERS: You didn't, I assume, make any attempt to weigh budgetary considerations and safety considerations, did you?

MR. COOK: Not at all.

CHAIRMAN ROGERS: You weren't qualified for that?

MR. COOK: No, sir.




CHAIRMAN ROGERS: And you assumed other people were doing that?

MR. COOK: Yes.

CHAIRMAN ROGERS: You had no reason to think the other people were not qualified to do that, or you had no reason to think that people who were weighing those considerations were not qualified to do it?

MR. COOK: I had no reason, except I would have to qualify that not from the standpoint of criticizing anybody, but it relates to something that I said earlier - and I know that I have the [381] highest regard for the professionalism in NASA; I worked in several agencies, and it is the most professional agency I have worked for - as far as the depth into which these things are analyzed.

And so I wouldn't want to reflect at all on that, and particularly in the Comptroller's office. But going back to what I said earlier, we had a developmental budget for the SRBs that was coming to an end. We have a budget, a developmental budget, that is divided into three parts. We have filament wound case, which is, as you know, is the substitute lightweight solid rocket booster that is being developed right now.

We have tooling, which is mainly based upon an effort to get the tools in place at the factories, so




that when the flight rate got up to 24 per year we could support that flight rate.

And the third thing is residual development, and that was special studies that came up and other things. I'm sure others could explain it more fully than I could. But it was special studies that came up, either anomalies or improvements. I think we had a nozzle erosion study going on that was funded under residual development.

Plus, we were trying to figure out how we could qualify a second source to build the SRBs. That was in residual development. But that budget was coming down very steeply, and, at the same time, the flight rate was going up very rapidly. And, to me, that creates a very difficult situation where a lot of judgment is required to figure out what you're going to spend your developmental money on.

I had no reason at all to question anybody's - the way that was weighed. All I am saying is that it puts the Agency, it put me, having to analyze it and make recommendations, in a spot where you just had to use real good judgment to say what was needed and what you were going to do if a surprise came up and you had to come up with a whole lot of money to cover one of these things.




CHAIRMAN ROGERS: But still what you've just said relates to the budgetary considerations. My question was did you have any reason not to rely on the recommendations of the people who were highly qualified to make recommendations insofar as safety was concerned?

MR. COOK: No, sir.

CHAIRMAN ROGERS: So you don't now and you never have said that you distrusted or were unable to rely on those people who were primarily responsible for safety features?

MR. COOK: Not at all, no. I didn't.

CHAIRMAN ROGERS: And so you felt that to perform your job in terms of the Comptroller's office you were anxious to find out, if you could, what plans were being made that might impact on the budget?

MR. COOK: That's right.

CHAIRMAN ROGERS: And you didn't feel that you were in a position or should you make those decisions about what should be done with the space program?

MR. COOK: That's right.

CHAIRMAN ROGERS: And so that the memo, which has been given a great deal of attention, sort of suggests that you were taking issue with the people who




were highly qualified to make those judgments, when in fact you weren't at all. You were looking to see how much it might cost if certain changes had to be made; is that right?

[382] MR. COOK: That is right. In fact, I have made a point on the second page here. "It should be pointed out that Code M management is viewing the situation with the utmost seriousness." And I had no reason to doubt that, and I didn't as time went on. In fact, in the fall the reports I was getting, because every time I had to make my report I would ask the program people about the situation and about the O-rings, what was happening with the O-rings, and in fact we were seeing, as I understood it, there was erosion, according to the records I was given in the summer of 1985.

But, as I understood it, what was reported to me was there was a flight in the fall of 1985 where there was no erosion at all, and I reported that back to my management. In fact, I was reporting at that time that it looked to be as though the fix for the O-rings might be less serious than was earlier indicated. At the same time I reported or at least I was told - I have to look at my own files, my own documentation - that because they weren't exactly sure of what was causing the




erosion, for instance, the putty was an issue and it was mentioned, and we had somewhere around a $50 million estimate to requalify new putty if we had to do that.

In fact, I think we were going to have to do that anyway because the asbestos was going to have to be gotten rid of. And so there was that. There was the unseating of the secondary O-ring that the capture feature was supposed to take care of.

So we still weren't sure, but at the time I was reporting that it looked as though we might not have a major budgetary hit during fiscal year 1986 from the O-rings. They were also, as I understand it, combining the test of the capture feature with another test to save money.

CHAIRMAN ROGERS: I think the Commission and I certainly understand what you are saying. And you were reporting back to the Comptroller's office, and to perform your job on budgetary considerations, and you were picking up information from different sources as to what they might be thinking about. You were not passing judgment, though, yourself on what they should or should not be doing, were you?

MR. COOK: Not at all. In fact, I was new to the program and I felt I was hearing things that I expected. I wasn't the only one that was hearing in the




Comptroller's office. I had no reason to believe that. But I felt for my own education and for my own professional judgment that I would write it up as I heard it, and that is what I did. I was not passing judgment.

CHAIRMAN ROGERS: Since the time of the accident - well, let me withdraw that.

Well, since the accident occurred have you had discussions with people about your memorandum of July 23, 1985? [Ref. 2/11-21]

MR. COOK: Yes, particularly since it showed up in the newspapers.

CHAIRMAN ROGERS: Did you have discussions with people before it showed up in the newspaper?

MR. COOK: I had given it to my boss just as a matter of giving him documentation.

CHAIRMAN ROGERS: But no one else?

MR. COOK: Someone else? Well, my boss and the other, the former SRB analyst that I worked with very closely.

CHAIRMAN ROGERS: Anyone out of the office?


CHAIRMAN ROGERS: And so you were not involved in the publication of the document yourself?

[383] MR. COOK: No, I was not.




CHAIRMAN ROGERS: Since the accident have you written another memorandum in connection with the accident?

MR. COOK: Yes, I did.

CHAIRMAN ROGERS: What prompted that?

MR. COOK: The heat of the moment. I did write another memorandum and what I was saying essentially was that, given all of the information that was coming in, I felt at that time that, number one, it had not been demonstrated what caused the accident. The evidence that points to the SRB is either circumstantial or interpretations of photographs.

But I felt that the problems that I had been apprised of during the course of, now it wasn't just the first weeks on the job, it was several months, ought to be looked at seriously enough so that whatever happened this needed to be taken care of. The O-ring problem needed to be taken care of before we could look at the shuttle program as being completely resolved.

And we had some other major budgetary issues that came up in that connection.

CHAIRMAN ROGERS: You still were doing it in terms of the budget? I mean, was that the purpose of writing the memorandum after the accident?

MR. COOK: Yes.




CHAIRMAN ROGERS: Did you have reason to think that efforts would not be made after the accident to investigate it thoroughly?

MR. COOK: No. In fact, I knew that across the street they were doing the same analyses we were doing.

CHAIRMAN ROGERS: Then will you explain again why you wrote the memorandum?

MR. COOK: To document what I felt were all of the budgetary implications of the situation.

CHAIRMAN ROGERS: Only budgetary? Was there any other purpose? Well, if you'd rather not answer, that's all right. I'm just curious about why you wrote the memorandum. I mean, it doesn't sound as if you had budgetary considerations in mind. It sounds differently. But I just wanted you to have an opportunity to tell the Commission why you wrote it.

MR. COOK: I wrote it because I felt that it was a serious enough situation that I didn't think that until these various issues were resolved with the SRBs that I had been involved with, that they had to be taken care of before the shuttle could safely continue.

CHAIRMAN ROGERS: Did you think your engineering experience, based on the short time you had been with NASA, improved your ability to pass




judgment on what others had decided? Well, here again I really don't want to press you.

Do you have anything else to tell the Commission?

(No response.)

CHAIRMAN ROGERS: Any other questions?

DR. WALKER: When you referred to "across the street" did you mean Code M?

MR. COOK: Yes, sir.

MR. HOTZ: As far as you know, in the preparation of the fiscal 1987 NASA budget were there any provisions made for an O-ring or a seal improvement program?

MR. COOK: For fiscal year 1987?

MR. HOTZ: Yes, the current budget.

[384] MR. COOK: Not to my knowledge. Now there was to be, as I said, a firing of the QM-5 test article this week, which is a budgetary item, but to my knowledge there was not a separate budgetary proposal going into the 1987 budget at that time for this problem.

MR. HOTZ: But in your last paragraph here you expressed an opinion or a recommendation that there should be some sort of a provision in the fiscal 1987 budget.

MR. COOK: Yes, sir. I thought there should





MR. HOTZ: And to your knowledge there was none?

MR. COOK: Well, but this is just beginning, really, the thinking about what - to my knowledge, NASA has not yet put together a complete - well, how could it - analysis of what will be needed to remedy any requirements that grow out of the investigation of the accident.

MR. HOTZ: Yes, we understand that. We're talking about their judgment before the accident, just as an ongoing program improvement.

MR. COOK: There was no separate item that I know of now, at the level I was dealing with, the composite numbers that I was dealing with. I'm sure there were studies and analyses that were part of a total project support number, for instance, that dealt with it, but there was nothing on the order of, say, the nozzle erosion study, which was a $3 million or $4 million study.

MR. HOTZ: Thank you.

CHAIRMAN ROGERS: Mr. Cook, I just received a copy of the memorandum that I referred to previously, which is dated February 3, 1986, and the other Commission members have not had a chance to look at it. suer.

(Viewgraph.) [Ref. 2/11-22]




I would propose to let them take a look at it during the lunch hour and then we can resume and they may have some questions to ask and you may have some comments to ma

Okay. Let's have a recess for lunch.

(Whereupon, at 12:50 o'clock p.m., the Commission recessed, to reconvene at 2:30 o'clock p.m. the same day.)

(2:25 p.m.)







CHAIRMAN ROGERS: Mr. Cook, is that chair convenient for you or would you rather have a different kind of chair?

MR. COOK: I am much more comfortable just to stand up.

CHAIRMAN ROGERS: Well, let me begin by saying that I had a chance to talk a little bit with Mr. Cook during lunch and learned that he had in fact been asked to prepare a memorandum subsequent to the accident on budgetary matters, and Mr. Cook pointed out, and we discussed the fact that in the initiation of the memo he included some material in there that did not strictly come within the budgetary request that was made.

Nonetheless he said in his testimony this morning that he did it in the heat of the moment, and I thought maybe, Mr. Cook, you would want to follow up on the discussions we had about [385] how you relate to the engineers in NASA and the others in terms of their ability and their qualifications.

MR. COOK: Kind of to paraphrase what we covered this morning, it is a requirement of my job and of everybody in the office, each of which has its own




hardware, to handle, to try to understand as much as possible about the engineering side of things as we can. There are plenty of guys there who do it a lot better than I do, and even some of the more complicated parts of the program, such as the space shuttle main engines, and we rely on the program office in the Office of Space Flight and we rely on the conversations we have with the Centers, with Marshall and Kennedy and other places, and we try to come as best as we can to an expression of what the engineering issues appear to be, because we want to give accurate cost estimates when they go up to the Congress.

And the kind of support we get from the program office is, by and large, superb. I mean, the professionalism and the cooperation that we get from these people is excellent. And we have kind of a middle man role of trying to translate these things back into language that can be used for the cost and price analysis and also to give our budget presentations to the Congress.

One of the things that, immediately after the accident - and it is still going on - is that our office was required to come up with some very fast estimates of what the implications were of some of the possibilities that were being talked about at that




time. And, of course, the external tank and the boosters fell into my area for analysis.

And so essentially what I did was to try to pull together all of the possible budget implications that I could think of. Again, I spent a lot of time across the street, a lot of time talking to people, trying to put into my own words what I felt would be needed for NASA to address the SRB question, if it happened to be an SRB problem or perhaps even if it didn't, because, even if it wasn't an SRB problem in the accident there were still things that we had been concerned about that had been well documented during the previous year, including the putty, including the O-rings, that we wanted to take a look at.

And I felt - and I think the people across the street felt also - that this was a particularly crucial time to kind of lay it all out, all of the problems we saw, all of the things that would need to be examined and really understand if we were talking about a four-month delay, an eight-month delay, a year delay or exactly how long it was going to take.

And right now I believe we are running those options in more detail - different length of delays depending on in large measure the outcome of what you folks are deliberating.




I don't know if it would be useful to run down the issues that I had included. I don't think there is anything new in there that has not either been before the Commission or shortly will be. But I would be glad to do that.

CHAIRMAN ROGERS: Well, why don't you do that, Mr. Cook? I think that - you are speaking now about the memorandum subsequent to the accident.

MR. COOK: Yes, sir.

CHAIRMAN ROGERS: Our plan is to, because we don't have a machine we can do it here, to ask NASA to release this memorandum that we're talking about a little later on when we finish today. But I do think it might be useful to have you summarize what is contained in the memo and any comments you care to make about it.

[386] MR. COOK: Let me just briefly run through those things, then. There are just a few items. One is that the capture feature that was to be tested on the QM-5, I said, is something that has not yet been accepted for use on the steel SRB cases, so if this is going to be a solution to the unseating problem, then that would be something that during the next few months would have to be tested and qualified.

The second thing was it is clear that the field joint putty plays a significant role in O-ring




erosion. It is also an asbestos problem. And so flight qualification of new putty is recognized to be a major unbudgeted cost item, meaning up until that time, the time of the incident, it had not yet been costed out and put into the budget we were submitting to Congress.

Any effects of environmental and weather factors on the putty and O-rings may have design implications which require further investigation. I noted that eight SRB segment sets are in manufacturing flow at that moment, and that meant simply that from the time Thiokol pulls them off the shelf and starts loading them up with propellant until they get in to the Cape to be assembled for flight we have eight SRB flight sets that are moving through that process. And depending on any action that we have to take to retrofit those cases with either a capture feature or any other new design feature, something has to be done with those.

We have either got to scrape that stuff out, that propellant out, or they have got to static fire it, or, I suppose, conceivably think about doing a retrofit with the case segments in place. Now again what I am doing is reporting on the resource implications. I have no idea what the detailed engineering implications are here.

Again, what we're trying to do is come up with




a cost estimate of what it's going to take to retrofit case segments. Five flight sets of hardware remain on the shelf at Thiokol which should not be loaded until the O-rings are repaired, and so there is a possibility of a shutdown or a slowdown at Thiokol while they wait to see what can be done with those flight sets.

I noted here the problem with the leak test ports, because this is not something that I had put in any previous analysis that I had given to the Comptroller's office, that something needs to be looked at as far as those leak test ports, and if there is anything that needs to be done in regard to assuring that those are put in place properly or tested properly.

And another question had come up at some point whether we had any case cracking or case rupture, and I simply made a note that the procedures for checking case cracks, I think there was a test at Thiokol where there was a burst of a case because of a crack in a stiffener ring bolt that raised some question about whether we have got to take another look at that. And that relates to our budgetary issue because we have been watching very carefully the attrition rate for solid rocket motor hardware.

We have got in our budget an assumption that somewhere around five percent of all of our flown case




segments will be lost to use either because they are damaged when they hit the water after the SRB comes down from flight. We lost a couple of flight sets when they were sunk. We lost some in an accident out at Thiokol, and we have got some segments under repair.

So we are trying to come up with the best estimate we can of how many flight segments over the lifetime of the 20 per use configuration have to be replaced by new hardware. We have been working a 5.1 percent projection. It has actually been higher than that. And so we're [387] wondering at this point whether the possibility of a crack occurring might lead us to have either a higher attrition rate or additional expenditure for detecting these.

Another issue was this thing that has been debated in the news - and again this is just something that came up in this context as a potential cost implication - as to whether anything was going to have to be assessed to see if instrumentation, software or launch and training procedures would be implicated, if the agency thought there was anything we could implement to have an abort mode during SRB ignition.

Now, as I understand it, particularly from Mr. Aldrich's testimony a few days ago, at this time I'm not aware of any possible abort mode that is being




discussed - and again that is something that would have to come from the engineers - but I cited this in here as something that from a budgetary standpoint we might have to take into account if the agency made a decision to install an abort mode during SRB firing.

The next item is that if the capture feature cannot be qualified for the steel segments and we have to reengineer the field joints, then there are three SRB segments for each booster, six per flight set, that one way or another will have to be reengineered.

And if that is the case, the lead time to tell the manufacturer to make a new segment that we have been working with is about 13 months, and so that has serious budgetary implications if we have got to remanufacture case segments and we're looking at that kind of lead time. We either have to have a crash program to manufacture them or we have a delay of that length of time. So that was kind of a crucial variable and that is another reason why we needed to cost out the test and cost out the capture feature as soon as we could.

The other thing is, I guess Number 9 is the attrition rate on the SRB segments which I just mentioned has been higher than the planning projections, and we just lost 22 more segments because of the accident. That throws us behind considerably in our




manufacturing flow because we're only producing, I believe, one of these segments a month, or maybe two a month. And so now we have to take a look at that, and even if we suspend flights for a period of months we're going to have to come up with a program where we can make up for those lost segments and get them back into the flow.

Again, that is - that depends on the capture feature or any other fix that is made to the SRBs to accommodate whatever the results of the investigation is or, as I guess some people felt ought to be done anyway and was going to be done anyway - I mean even before the incident - the capture feature was to be tested. It was to be tested this week and installed. So the presumption is that that was going to happen and would be going on anyway.

The other item is that the filament-wound case project needs to be examined because it, too, had safety issues. There was a test where under pressure the case showed a rupture. The case was to be retested and there was a difference of opinion as to what the likelihood was going to be of the case passing muster as far as its overall flight safety posture was concerned.

And that too had to be factored in because our ability to meet the Vandenberg launch schedule after




July depended very much on having those filament-wound cases and the filament-wound cases were also a part of the third production contract that was about to be negotiated between the agency and Morton-Thiokol.

[388] So based on all of those considerations, if we went through with this program I was projecting - and again this is just a budgetary analyst's estimate - I was projecting a nine-month or longer suspension of flights to deal with all of these things.

CHAIRMAN ROGERS: Thank you very much, Mr. Cook. I appreciate that.

Summarizing your first memo, of July 23, 1985, as you have said several times, it was done for budgetary considerations and you did not intend to pass judgment on any of the engineering features as such. You were looking at it for budgetary purposes?

MR. COOK: Absolutely. That was all I was, that was all I was able to do.

CHAIRMAN ROGERS: And you were satisfied with the performance and ability of the engineers that you dealt with at NASA?

MR. COOK: Yes, and I would say particularly the fellows in the Propulsion Division at headquarters. I thought it was an extremely professional group. It was a great deal of help to me particularly getting on




board and getting up to speed on all of these things. And I thought they were an excellent team that had the interest of NASA and the program entirely in mind, and I had complete confidence in the information that I was receiving.

CHAIRMAN ROGERS: Thank you very much.

Now I asked you this morning about the reason for the memorandum subsequent to the accident, which is dated February 3, 1986. And it subsequently turns out that you were asked to provide a memorandum to the effect along the lines of your summary just now. In other words, you were asked to do that by Mr. Mann?

MR. COOK: Yes, sir.

CHAIRMAN ROGERS: And the memorandum that is dated February 3 that you have just summarized was in response to that request, and I think your summary of the memorandum is very good and it explains to the Commission your motivation.

I would like just to ask one question about the memo. You say at one point when you are referring to the engineers, I believe you say - well, let me read the whole thing. "It is also my opinion that the Marshall Space Flight Center has not been adequately responsive to headquarters concerns about flight safety,




that the Office of Space Flight has not given enough time and attention to the assessment of problems with SRB safety raised by senior engineers in the Propulsion Division."

Now this is the part I want to ask about. "And that these engineers have been improperly excluded from investigation of the Challenger disaster." In light of the work of this Commission and the investigations that are being conducted now at Kennedy, are you still of that view?

MR. COOK: Well, let me just comment very briefly on that paragraph. I editorialized a bit at the beginning and the end of this, and I did so on the basis of my general point of view in retrospect on some of these issues, and since I wasn't prepared to comment on this memo at all today I'm not going to try to go into a lot of detail about the first two items.

CHAIRMAN ROGERS: Well, it is really not necessary. I think the thing that concerns me most is whether you have confidence now that the investigations are being properly conducted.

MR. COOK: Well, if I had access to my files and time to write, I would try to be more specific. That is all. But let me say this. The last item, frankly I was amazed that when this incident occurred the engineers in Washington were over there in their


[389] 713


offices getting the data on the investigations from the newspaper and the media, and now and then phone calls from guys down at Kennedy about what was being found.

These were the top propulsion engineers who prepared reports for the Office of Space Flight and for the Administrator and for us. I just couldn't understand why that group wasn't down there going through the data and looking at the photos and everything else. Frankly, and I will be honest with you - and I'm not intending to explain why that was or criticize anybody - I was just, in a way I was glad because I could go over and talk to them and get my information from them.

But I just couldn't understand why the headquarters propulsion office didn't have their guys down taking part in that. I have no question whatsoever about the investigation or the Commission's work. I don't feel I'm really competent to make much of a comment on that, although I must say I am glad that you all are having public sessions and that it is a presidential level group. I think that is absolutely in order and really needed.

The only thing that I would urge would be that as much as you can to get just the ordinary working guys, such as me and the engineers and the guys from the




Marshall S&E Lab, and if you can get them in from Thiokol, just the ordinary engineers who break these things down, who look at them, who call each other on the phone and say hey, look what I found here. You've got to take a look at this. And that is what I hope will be included.

And I think that if everybody who has firsthand knowledge and experience and feels they can come up and talk freely, I think that you will have a good investigation.

CHAIRMAN ROGERS: Well, I assure you, Mr. Cook, we do plan to do that, and we have plans made.

Secondly, you told me during the lunch hour that you had great confidence in Jess Moore and the people who work for him - that is a fact, isn't it?

MR. COOK: Yes, sir.




CHAIRMAN ROGERS: When you wrote the second memo of February 3, you intended that to be used for internal purposes only?

MR. COOK: Absolutely.

CHAIRMAN ROGERS: You have no objection now, in view of what has transpired, if it is made public, because we want to be sure as a Commission that we don't appear to be holding anything back, and President Reagan has wanted us to be sure to lay all of the facts on the table and to let all be known, and so you have no objection if we make that memorandum public?

MR. COOK: No, sir, I don't, although I must say that I think everybody who really works on this needs to understand, and I am not addressing the Commission, I am addressing I guess people who would be reading that, the complexities of the situation and the difficulties that any individual has in coming to conclusions.

CHAIRMAN ROGERS: Yes. Thank you.

You also mentioned this morning that you wrote the memo in the heat of the moment, and I assume you were, like everybody else in the country was, terribly disturbed and upset by the accident, and it was in that spirit or at that time when you wrote the memorandum. You didn't really mean to adversely criticize for public


[390] 716


consumption your associates or people around you, did you?

MR. COOK: No, I didn't, but I must say, I didn't say anything in there that I didn't feel I had - that I couldn't back up and wouldn't stand by.

CHAIRMAN ROGERS: No, I understand. I am really not asking for you to back down at all. I think to understand the contents of the memo, it is helpful to have you say what you have said, I just mean that it was done in the heat of the moment, and I think that has helped us understand the memo.

One other thing, and then I will stop.

Sometime subsequent to this, I understand that you decided to change jobs in the government.

Could you tell us about that?

MR. COOK: Yes, sir. This had been going on for some time. As a matter of fact, I had worked before at the Treasury Department, and it just so happened by coincidence that I got an offer from them to return to the Treasury Department last week. This had been something that had been in the works for several weeks, and I will be reporting to work at the Treasury Department next week.

But it is a coincidence, and it doesn't have anything to do with this.




CHAIRMAN ROGERS: It was voluntary on your part?

MR. COOK: Absolutely.

CHAIRMAN ROGERS: Thank you very much.

Are there any other questions?

(No response.)

CHAIRMAN ROGERS: Thank you very much, Mr. Cook. We appreciate your appearance and your frankness.

Mr. Mann?

(Witness sworn.)

CHAIRMAN ROGERS: Mr. Mann, I want to ask you a few questions about the memorandum that was from Mr. Cook to you dated July 23, 1985.

What were the circumstances surrounding that memorandum, do you remember?


[Please note that some of the titles to the references listed below do not appear in the original text. Titles are included to identify and clarify the linked references- Chris Gamble, html editor]
391] [Ref. 2/11-21 (1 and 2 of 4)] MEMORANDUM- PROBLEM WITH SRB SEALS.[Memo from R.Cook to M. Mann; Subject: Problem with SRB seals; Dated: 7/23/85.]

[392] [Ref. 2/11- 21 3 of 4)] MEMORANDUM- PROBLEM WITH SRB SEALS. [Memo from R.Cook to M. Mann; Subject: Problem with SRB seals; Dated: 7/23/85.] [Ref. 2/11-21 4 of 4] [Marshall Space Flight Center; SRB- SRM Field Connections; Dated: April 1978]

[393 - 395] [Ref. 2/11-22 (1, 2 and 3 of 3)] [LETTER FROM R.COOK TO M.MANN (Feb.3, 1986); Subject: Required Solid Rocket Booster Improvements]


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MR. MANN: Yes, sir.

Rick Cook was a newly assigned employee, and the issue of the charring of the O-rings had come up in the normal course in the Office of Space Flight discussions. It was a perfectly open issue. It was discussed in an activities meeting, and as part of his training, I asked him to go talk to the engineers and to give back to me a report on what was exactly involved in the charring and what the budget implications were, and that was pretty much a normal part of the way we work. We try and keep, as Rick said, keep abreast of all the technical issues that have a potential budget impact.

CHAIRMAN ROGERS: What is your title, and what are your responsibilities?

[397] MR. MANN: I am the Chief of the STS Resources Analysis Branch. It is within the Office of the Comptroller. We do the - we prepare the budgets. We work with the program office to prepare the budget for the Office of Space Flight and the Space Station. We also do independent reviews periodically of the issues




that have a cost or a budget implication such as pricing policy for the Shuttle or particular cost issues.

CHAIRMAN ROGERS: And how long have you worked for NASA in that capacity?

MR. MANN: I have been in the Comptroller's office since 1980.

CHAIRMAN ROGERS: And you are Mr. Cook's superior officer?

MR. MANN: Yes, sir.

CHAIRMAN ROGERS: Now, when you received the copy of this memorandum, do you remember what you did with it or what consideration you gave to it and what actions you took?

MR. MANN: I did several things. One, I talked to Rick about it. One of the things I wanted him to develop was the ability to do a cost estimate, to actually take an issue like this and talk to the engineers and be able to come back with alternatives, programmatic actions, and the costs of each, and some judgment as to the relationship between the alternatives. And his memo hadn't done that, but it was kind of early, frankly, in his training to expect him to be able to do that.

I also took the memo to my boss, the Deputy Comptroller, and the Comptroller. I asked Rick to take




it back to the engineering staff in the program office and discuss it with them, one, so that they knew what he had written, and two, so that if they had any - if they wanted to comment on it, that they would have that opportunity.

So I discussed it with my immediate supervisors, and I had it sent back to the Office of Space Flight, and then I also went to discuss with the engineers if the memorandum really reflected the situation as they saw it. And in those discussions which I got the feeling that maybe the memo overstated the concerns, that there were quite a few actions being taken within the program office to resolve the issue, that there were extensive reviews going on, as there are in almost any technical type of review.

So I was satisfied that it was in the proper technical channel, that it was being handled properly, that it was being handled rigorously and thoroughly, and over time, over the next couple of months, as I saw the report come out, the reports and the statuses within the program office, the immediate concern died down.

CHAIRMAN ROGERS: So you thought the points that had been raised by Mr. Cook in that memorandum were being taken care of, and you thought adequately as far




as you could tell?

MR. MANN: Yes, sir.

CHAIRMAN ROGERS: Are there any questions for Mr. Mann on this particular letter?

DR. WALKER: I have a question, Mr. Chairman. I know that developmental programs within NASA have a contingency as a part of the budget to take care of unanticipated costs.

Now, with the Solid Rocket Booster Program, which I presume was operational at this point, was there still a contingency in the budget so that some of these problems identified with the [398] seals, for example, could be handled without additional monies being authorized or appropriated?

MR. MANN: Sir, there are three levels of reserve within the budgets. There is a project level reserve which would be within the Solid Rocket Booster Project. That particular level of reserve would not be sized to handle any kind of significant redesign effort. It is more an operational type of reserve.

There are then level 1 and level 2 reserves that are held at the headquarters or the Johnson level, and those reserves are really available to handle and to rebalance the program for particular problems, and those




kind of reserves would largely be used for any kind of significant effort.

There is a third reserve that is called the Changes and Systems Upgrading Line, and it appears specifically in the NASA budget, and that is a reserve that the Administrator reviews, that he has available for improvements or significant upgrades to the program. And there was no - although in the Solid Rocket Booster, there was no specific reserve for this particular situation, there were reserves within the program that could be applied to it, and there was no budget determination made in terms of was there adequate funding? There was no impact on the engineering process as a result of the budget.

DR. WALKER: I understand that the July letter of Mr. Cook's was essentially a training letter. I was a little surprised to see that it didn't discuss whether or not these problems would be within the contingency or would require additional appropriations.

Would you have expected that this letter would have discussed that point?

MR. MANN: Yes, sir. What we really do is we try and size a problem. It is one thing to understand that there is a problem. It is an altogether different issue to be able to put a cost on it and then to




determine where the Agency can come up with the funds to resolve it.

And so I wasn't particularly dismayed that in this particular instance it was, I believe, the first one that Rick had done, the first issue he really reviewed, that he had not been able to do a thorough cost analysis of it. But typically, that is exactly what we would expect. We would expect that here are the alternatives, here is the cost of each alternative, and this is where we think we can find the money within the overall budget to support it.

MR. ACHESON: For the record, Mr. Mann, does the Budget Division have its own engineering staff?

MR. MANN: We have some engineers on the staff, but they are not on the staff to be engineers. It just so happens that that is their technical background before they got involved in cost work. Our office doesn't try and do any kind of engineering evaluation or safety evaluation, which is why when I was assured that the issue on the charring was being resolved in the proper engineering channels, we pretty much stopped working on it.

MR. ACHESON: So on engineering and safety questions you are entirely dependent on the other engineering divisions of the Agency, is that not so?




MR. MANN: Yes, sir.

DR. RIDE: I think it might also be appropriate to point out that Mr. Cook referred to some detailed engineering analyses earlier and recommended that the Commission review those, and [399] we were given those Marshall and Thiokol engineering reports yesterday, and have access to all of the data by the engineers on the program.

CHAIRMAN ROGERS: There is no doubt about it. Mr. Cook referred to these documents, and somebody is suggesting maybe that we have not had access to them, and in fact we have them, as Dr. Ride has said. We have all of the documents we have asked for, and they are included.

On the subsequent memo that I talked about, February 3 from Mr. Cook to you, I gather that you requested a memorandum of sorts from him after the accident?

MR. MANN: Yes, sir. We were trying to frankly size the potential impacts to the NASA budget as a result of the incident. I asked Rick to specifically do a cost estimate for the SRB project in the event that we had to make some change to the cases, and I specifically asked him to do that particular type of evaluation to try and size the budget impact without




really knowing what it would be, that we were doing the same kind of analysis on the main engines, on the external tank, as a part of trying to see what the size of the budget problem would be.

CHAIRMAN ROGERS: He testified that he responded to that request in the heat of the moment and wrote the memorandum which we have referred to.

Were you surprised at the contents of the February 3 memorandum?

MR. MANN: Frankly, I was. I had specifically asked for a cost estimate, and I specifically needed a number, this is a $20 million problem, this is a $100 million problem, to integrate that with other estimates that we were doing on the rest of the program, and frankly, the memorandum didn't provide that kind of information. It had some useful insights into the particulars of the program, such as how many motors we had in inventory, but it didn't really come down to what I was trying to accomplish.

CHAIRMAN ROGERS: Any other questions?

(No response.)

CHAIRMAN ROGERS: Thank you very much, Mr. Mann.

Mr. Moore?

Mr. Moore, you have heard Mr. Cook's




testimony, and his testimony specifically about the two memoranda that we talked about.

Do you care to make any comment on this memo?






MR. MOORE: Yes. I would like to make a few general comments, Mr. Chairman, and then I would like to introduce the division director, if I can, of my Propulsion Division who manages all of the NASA headquarters engineers on this, to also make some comments.

The two memos that were in question, I guess I saw the first memo that was dated on July 23, I believe, was that date. I guess I saw that for the first time on Sunday, and I think that there are some statements that in general are fairly correct in that memo. I think there were some areas that were somewhat out of context or a little bit exaggerated, but in terms of the activities that were going on in the program, I believe that our Propulsion Division, and I believe the Marshall Space Flight Center were taking all of the prudent actions to try to lay out a [400] program that would help us get a better handle on what we had been seeing in some of the previous flight experiences.

With respect to the memo that you just talked about on February 3, I just saw it last night, I guess,




for the first time, and although there is some good information in there regarding the number of flight cases in inventory and so forth, at this point I didn't know the intent of that memo was the budget, and I was very surprised at the last paragraph in there where it seemed to say that we were not paying enough attention to flight safety. And under no conditions had I heard any of my people come up to me and say any of the flights were not safe for launching. So I was a little bit surprised by that particular comment in the memo.

And I also think we have had extraordinary cooperation out of the Marshall Space Flight Center in terms of working with us on this problem. The Thiokol test program has been under way for a number of months now, since back early in 1985, and in fact, back in the July timeframe some money was expended on long lead hardware in the event some of the tests that we had aimed for the QM-5 program, which was a test program that we were planning to run coming up this week, as a matter of fact, in the event it showed different kinds of data, we would have a leg up on this problem so we could go and fix it.

I would also like to emphasize to the Commission that we were simply trying in this program, in this demonstration program and in the test programs, to try to get more margin into a situation that we felt




was safe for flight even though we had seen some of these O-rings and so forth. And so our programs focused on trying to get more margin in this thing.

And as was indicated in the previous testimony, we had planned to fly the filament wound cases on the upcoming Vandenberg launch. They were lighter weight cases, and we did have some different concerns. But that QM-5 test, which was a full scale test of the filament wound case, was an important article for us to test some of the analysis that had been done and also some of the laboratory tests that had been done to try to get a better handle on exactly the behavior of this overall joint.

And our plan was to take those tests and then make a decision in terms of what our next steps were relative to the continuation of this program.

And I would like to ask Mr. David Winterhalter, with the Commission's permission, who is my Division Director for Propulsion, to come up and into this whole area, if that pleases the Commission.

CHAIRMAN ROGERS: That is fine.

Let's see if there are any questions for you.

DR. RIDE: I have one. I think Mr. Cook implied that there had been a decision made to give you a little additional in-depth insight




incorporate a capture device in the field joints.

Had that decision been made?

MR. MOORE: That has not been made to my knowledge, no, Sally. I was not aware - we had not made that as far as the overall program was concerned.

MR. ACHESON: One more question.

Are you aware, Mr. Moore, of any personnel at the Marshall Center or elsewhere who have been excluded from the accident investigation who have anything to offer?

[401] MR. MOORE: I am glad you raised that. I was thinking about commenting on it, but I did not. The Marshall Space Flight Center has hundreds of people at the Huntsville Operations Center, which is a support center to every Shuttle launch involved in the detailed analysis of this accident. They are propulsion people. They are worried about the Shuttle main engines. They are worried about the external tank. They are worried about the solid rocket booster. In addition, we have contractor personnel there from all the supporting contractors on this program.

I think what Mr. Cook was referring to was that at the outset, when we set up the interim board, immediately after the accident, we basically impounded all the data associated with this tragic incident so




that we could get a handle on the control policy on this particular data. We are now in the process of setting up formally our task force, and we plan to involve the Marshall Space Flight Center and other NASA centers, headquarters personnel in that analysis.

And so I think Mr. Cook's observation was probably correct at the outset because everybody was not allowed to be brought into the picture right up front, and that was because we impounded data, and we were trying to put very tight controls on access to any data associated with this so that we could preserve it for our accident investigation.

MR. ACHESON: Thank you.

CHAIRMAN ROGERS: Thank you very much, Mr. Moore.

MR. MOORE: I would like to introduce Mr. David Winterhalter.

(Witness sworn.)

CHAIRMAN ROGERS: Welcome, Mr. Winterhalter.

Please proceed.






MR. WINTERHALTER: Mr. Chairman, members of the Board, first let me just tell a little bit about the division that I have. My title is Acting Director of the Propulsion Group at headquarters. It is a division. Within the division we have the overall policy type generation and overall direction of the major projects dealing mostly with the people at the Huntsville Marshall Space Flight Center. That includes the external tank, the solid rocket boosters, and the Space Shuttle main engines, and the various testing programs that go along with those.

I have a group that is broken up pretty much into those projects. They are small groups, one to three people per project, very senior people. I would say that they average over 20 years service in engineering and in manned space flight in the propulsion area, most of those years spent by these people at NASA, very well respected throughout the Agency, called upon many times for their outstanding judgment.

I don't want to address Mr. Cook's memo paragraph by paragraph at all, but I would like to mention that to my knowledge, the things that he said about the engineers not taking part in the




investigation - I mean, I knew that the time would come, as Mr. Moore mentioned, that they would have their opportunity, and about the noncooperation with the Huntsville folks, as Jesse mentioned, I feel like we are a real team. We interact well, we work well together. Like any [402] team, we sometimes have our differences, but we are usually able to work them out and carry a coordinated recommendation forward.

And that would go pretty much to any type of situation in what might come up within the program.

If we see something that is somewhat out of the ordinary, either in our test programs or in our flight programs, obviously there is an immediate evaluation to try to find the magnitude of the situation and see if it might have some type of effect on upcoming flights or upcoming tests, etc., to try to understand if maybe we should slow down whatever we are doing and take another look.

Usually what we find is that in the initial evaluation it doesn't take drastic action to stop a program and stop a test program. What we have been doing is we have some low level analysis go on with prudent funding, and as we find out more about the situation, we decide that we don't need to work on it anymore, or in fact, we may need to step up the effort.




Now, to get the specifics here on this particular area, in the nozzle joint and the field joints on the solid rocket boosters, as soon as we started seeing any indication out of the ordinary of what we had expected of the situation, somewhat small nozzle O-ring erosion, there was immediate, an immediate effort set up at the Marshall Space Flight Center to start looking into that area.

Now, as the situation evolved, in 51-D the secondary nozzle joint O-ring erosion, the effort was stepped up somewhat, and that brings us up into the late spring, early summer of last year when, as it was discussed with you yesterday, the test program at Thiokol, their analysis programs, etc., were beefed up and put into a regular plan, and that has progressed through the summer, through the fall timeframe of a more and more intensive analysis and investigation, etc., culminating in a November-December timeframe where they picked some of the better candidates for joint improvement to be tested in the next resource in the test program. That happened to be a filament wound case, but a full-up solid propulsion motor.

Now, it is very expensive to do all of the testing in solid propulsion system so you try to make use of whatever resources you have at hand. So they picked some of the




better candidates to put into this test that has been described to you, and it had been planned for Thursday of this week, but it has since been postponed.

And that is sort of a summary of how we go about it in general, in that specific example.

I would rather defer to Mr. Mulloy for any more detailed discussion of that, but I just thought I would give you an overall feel for how we at headquarters look at things on an overall basis. My people work on a day to day basis with the Huntsville people. I know right after the accident everybody really wanted to get in and try to find out what happened, etc., but at our level we have other things to do. We try to take a look at the overall system and try to understand long term impacts, etc., and think through some various scenarios about how we might have to react to the total situation, not just on an individual system basis but on an overall basis, how do our systems interact with other systems. For instance, if there turned out to be a problem on the tank, what do we do in the engine program, what do we do in the solid rocket booster program to maybe free up some money to work on the other to make a more balanced program?

That is our job. As much as being an engineer, we like to jump in and really dig into the


[403] 736


details and roll up our sleeves and look at all of the data and that sort of thing that is not our job at this time. However, I expect, as Jesse mentioned, as he forms his teams, we have some particular technical expertise within my group, and I am sure that he's going to call on some specific people for help.

So that is what I am anticipating now.

CHAIRMAN ROGERS: Well, thank you very much.

It is fair then to say that after, or at about the time Mr. Cook's memorandum was written in July 1985, that you and your team were - had been and were at that time conducting a lot of investigations and doing a lot of work about the O-rings, and that you continued to do that all during this period up until the 51-L flight so that intensive work was being done by engineers who were highly qualified to do it, is that correct?

MR. WINTERHALTER: That is correct, sir, and I think some of the material that we presented to you yesterday will show that our own internal division meetings and our discussions with Jesse Moore, and our monthly meetings, etc., we talked about this area, we talked about what we were doing about it. We tried to talk about potential impacts if, in fact, various scenarios might work out, depending upon how much redesign might be required or desired, this is how it




would affect the budget, how it might affect schedules, when we could get it incorporated, etc. And so we were doing that pretty much for the last year. And as I mentioned, it sort of intensified as the year went on. But that is just sort of the normal way we do business.

CHAIRMAN ROGERS: And it is a very open organization, I gather, in terms of exchange of views and ideas, and everyone is permitted to write memos and make comments as he sees fit? But in the final analysis, the qualified people, the engineers and others who are assigned the responsibility make the decisions, have to make the decisions.

MR. WINTERHALTER: That's true.

CHAIRMAN ROGERS: And the decisions in this case were made pursuant to that policy.

MR. WINTERHALTER: That's true. I pride myself in our division to be particularly good team workers. We have our differences. We work them out. We can work them out with the centers. We do it all the time. And we carry a unified front forward, or we say, okay, this is the way we feel and we also give the other side, if that be the case.

CHAIRMAN ROGERS: And I suppose you have some confidence in your judgment because in 24 previous




flights you have made good judgments.

MR. WINTERHALTER: That's true.

Let me mention, at no time during that period did any of my people come to me and give any indication that they felt like there was any safety of flight problem in their area. We all worked - we were all working on the situation, but we were all involved in the flight readiness reviews that have been described here today. We take an active role in that, we can make inputs.

Mr. Moore is particularly good, and his deputy, Mike Weeks, involving everybody in these reviews, in these monthly reviews, and everybody is encouraged to feel free to speak out in any area. And let me tell you, sir, it happens. People aren't afraid to speak up. They are not [404] constrained by saying someone will take some action against them if they bring up something that is unpleasant.

VICE CHAIRMAN ARMSTRONG: Was it the view of your division, the Propulsion Group, that the seal design, as it was installed and operating in the Shuttle System, was safe and adequate?


VICE CHAIRMAN ARMSTRONG: But it was further your group's view that the margins on the seal design




were not such that it would not benefit from improvement, is that correct?

MR. WINTERHALTER: That is correct. We felt like it could be improved. We weren't happy with the situation the way it was. We understood that the testing had been done, the margins, etc., but as you are well aware, we are always striving to make things perfect.

MR. FEYNMAN: If the matter of Mr. Cook is more or less covered, I would like to ask some detailed questions about seals either from you or anyone else you wish to call, like Mr. Mulloy.

MR. WINTERHALTER: I would just as soon that Larry came up and talk about seals since he did such an adequate job this morning.

If you have some general questions -

MR. FEYNMAN: No, it is a specific, detailed question.

CHAIRMAN ROGERS: Thank you very much.

MR. FEYNMAN: We spoke this morning about the resiliency of the seal, and if the material weren't resilient, it wouldn't work in the appropriate mode, or it would be less satisfactory, in fact, it might not work well.

I did a little experiment here, and this is not the way to do such experiments, indicating that the




stuff looked as if it was less resilient at lower temperatures, in ice.

Does your data agree with this feature, that the immediate resilience, that is, within the first few seconds, is very, very much reduced when the temperature is reduced?






MR. MULLOY: Yes, sir, in a qualitative sense. I just can't quantify that at this time.

MR. FEYNMAN: Then you would say that I would conclude from that and the various things that you told me about the need for resilience and the lack of resilience within the first few seconds, and of course, it comes back very slowly, isn't it true, then, that the temperature at a low temperature increases the chance of a joint failure?

MR. MULLOY: The low temperature increases the time that would be required for the O-ring to extrude into the gap, and that would allow greater erosion on the O-ring, yes, sir.

MR. FEYNMAN: Did you have available - there was some kind of a temperature limit, then, on when you would say a seal was safe? Was there some kind of criterion that if the seal was lower than a certain temperature we cannot consider it safe enough?

MR. MULLOY: Yes, sir. The data that we had - as I stated, we are running extensive testing to understand the response of the seal under the specific conditions of 51-L, but the data available to us was the


[405] 742


procurement specification for the material that says that it will operate from minus 30 to 500 degrees F, and also, a great deal of test data in motors down at temperatures where you can see a difference in the resilience of the seal, for instance, going from 75 degrees down to 50 degrees, you can see that. We had those data available.

We had data that was presented on the 27th by Morton-Thiokol, some test data, that indicated a further reduction in the resilience of that if the temperature was down to 20 or 25 degrees. It was the judgment that with the resilience that we saw there, the shrinkage of the O-ring, and under the circumstances of the leak check that is done, that at that temperature the O-ring would perform its function.

Now, the data that we did see is refuted by some other test data, and that is why we are carefully running controlled tests under the specific conditions of 51-L to understand the response of that O-ring seal, and will it perform its function in that environment?

MR. FEYNMAN: Of course, after the event is a different circumstance, and I am not really considering that. That is not a fair question. It could be that you didn't notice the circumstances.

I just want to know, before the event, from




information that was available and the understanding, was it fully appreciated everywhere that this seal would become unsatisfactory at some temperature, and was there some sort of a suggestion of a temperature at which the SRB shouldn't be run?

MR. MULLOY: Yes, sir. There was a suggestion of that, to answer the first question. First, the data that was presented, it was the judgment that under the conditions that we would see on launch day, given the configuration that we were in, that the seal would function at that temperature. That was the final judgment.

There were data presented, as we have discussed, by some - by Thiokol engineering that there was a suggestion that possibly the seals shouldn't be operated below any temperature that it had been operated on previous flights.

CHAIRMAN ROGERS: Are there any further questions?

MR. ACHESON: One or two questions.

What is the pressure at which the tests have been run postflight to simulate this condition?

MR. MULLOY: That is the hydrostatic proof test, which is 112 percent of 1000 psi, or 1120 psi. But that does not simulate the rise rate that you have




with the motor ignition. That is a static pressure test.

MR. ACHESON: I assume that it would just take a very short time for the O-ring to become the same temperature of the surrounding ambient air since there is no insulation between the outside and the O-ring, is that correct?

MR. MULLOY: That is correct. There is a lag, and that is another part of the thermal analysis, to look at specifically, with transients in ambient temperature, how does the steel, the propellant and the O-ring track that ambient temperature. But your statement is true, it tends to track the ambient with some few degrees of lag.

DR. COVERT: What was the temperature at the time of the launch, please?

MR. MULLOY: The ambient temperature?

DR. COVERT: Yes, sir.

MR. MULLOY: I believe about 38 degrees.

Jess, is that correct?

[406] MR. MOORE: That is the number I have heard, 38 degrees.

CHAIRMAN ROGERS: Unless everybody is really eager to press this on, I think it would be helpful if we considered this in detail and carefully at the next session, and I would hope that we could ask individual




questions when we are at Kennedy, and we would prepare very carefully to have answers for all of these questions in a full session.

I would think that in order to do it with care and deliberation, that it would take probably a full day, and unless the members really want to press it now, I would prefer to do it at that time.

MR. MULLOY: Mr. Chairman, I would like to make a clarification of testimony.

CHAIRMAN ROGERS: Can I say that at that time we will consider the weather, temperature effects, environmental effects and all of those considerations which I think deserve a full day of testimony.

MR. MULLOY: May I clarify some testimony that I made this morning relative to the events on the 51-L and our observations, the rationale that we used given the O-ring erosion?

Some of the questions I have had from the media indicate that it wasn't perhaps as precise a statement as it could have been. As I stated, what I was concentrating on this morning was the case joint since that was the primary area of interest. All of the data that I presented, the 6 of 171, the 2 of the 6 and so forth was related to the case joints. I stated that in leading up to the 51-L flight readiness review, that we had had no significant erosion or no




erosion in the past year.

That is a true statement for the case joints. It is not a true statement for the nozzle-to-case joints. The April 1985 is when we had that secondary O-ring erosion on the nozzle joints, and we were watching that very closely, and we did have some subsequent cases of erosion on the nozzle-to-case joints which were well, well below the threshold of what our limits were on that.

So I wanted to clarify that in my statement, that was related to the case field joints as opposed to the nozzle factory joints.

MR. ACHESON: But was that erosion on the primary ring or the secondary ring?

MR. MULLOY: In April of 1985 is the one case where we saw erosion of the secondary ring, and that was on the nozzle-to-case joint. And that is when we went back and did some further extensive testing on that particular configuration, and we did have some after that. We did have some subsequent erosion on the primary ring, but never again on the secondary ring. And it was a very low level of erosion and deemed to be within the rationale for the flight after we had the secondary O-ring. We didn't have anything like that magnitude of problem as we continued up through the 51-L on that particular joint.




CHAIRMAN ROGERS: What do you mean by erosion? How do you describe erosion?

MR. MULLOY: Erosion is absolute removal of the material. It is like an erosion of a ditch by water. The material is totally removed, and it is a divot in the surface.

MR. ACHESON: By absolute, you don't mean removal of all the material.

MR. MULLOY: No, sir. I mean, when I speak of 38 mills of erosion, I mean that the erosion of the 280/1000 inch O-ring, that there is a bite in that O-ring, and it is a bite shaped elliptical type of erosion that is 32 or 38 mills deep, and it tends to be anywhere from 10 to 50 times the [407] length of the depth of the erosion is what I am speaking of. But the material is totally removed, and the eroded surface, the sheen is gone, but it is a very smooth surface.

VICE CHAIRMAN ARMSTRONG: Is the band that surrounds the pins on the critical items list?

MR. MULLOY: The steel? No, sir. That is a steel band, and it is not, because the - we have the cork over that to retain that. And on our analysis - and the reason again it is not is because the cork is a first failure point, and then when the motor is




pressurized, the band is so taut that analysis shows that it can't lift off, and therefore its heating is the same as the basic structure, and no thermal protection is really required in that area. The steel itself is sufficient to take that.

VICE CHAIRMAN ARMSTRONG: The cork isn't a structural member?

MR. MULLOY: The cork is not a structural member. Initially it was there for thermal protection, based upon the early flights. It also served the function of holding the band as we got the ascent thermal environments, and concluded that really, that the cork wasn't required there, we left it in that position because we still had to have something as a secondary restraint on that band, which provides a second protection device that keeps that band from being a critical item.

VICE CHAIRMAN ARMSTRONG: If the band which is under tension, as I understand it, were to snap, what would the effect be?

MR. MULLOY: Nothing as long as the cork is there. The cork would retain the pins.

VICE CHAIRMAN ARMSTRONG: It wouldn't destroy the cork?

MR. MULLOY: I guess to get enough - I would




have to look at analysis. I suspect to get enough strain to snap the band, you would probably crack the cork, but to get enough strain to crack the band, you have also overpressurized the motor. I don't know what - I don't know what the margin is between 1000 psi on the motor and how much stretch you could put into that band before it would break. But you would have to overpressurize the motor in order for that to happen.

MR. FEYNMAN: You spoke of erosion. There is also a phenomenon called blow-by, and I would like the answer to two questions, and the first is, during the last year where you said there was no erosion, was there any blow-by in the field joints? And second, are you more worried by blow-by or by erosion?

MR. MULLOY: Well, I am more worried by erosion with blow-by, and the reason for that is the erosion reduces the cross sectional area of the O-ring, and the erosion can be caused by two things, which is the direct impingement, and then the blow-by erodes it in a different area which further damages the O-ring and reduces its possibility of sealing.

Let me look at the data that I have provided you yesterday, and again, to be precise about my statements, the statements were leading up to the 51-L FRR, and I did state that after the 51-L FRR, we




disassembled the 61-C where we found some almost immeasurable erosion on the primary O-ring, almost immeasurable, like .004 inches of the 280/1000s. On the 61-A, which flew in October of 1985, we did record soot behind the primary O-ring with no evidence of erosion, and so what we were seeing there, again, the primary O-ring was displaced during the initial pressurization. There was some gas blow-by for probably from zero to 50 psi, probably very, very low, and then [408] the O-ring was seated, but that was a hot gas which pyrolysed the grease and putty, which is what deposited the soot. None of that came from the O-ring, because there was absolutely no erosion, the sheen wasn't even gone on the O-ring. There was no indication of heat effect on the primary O-ring.

CHAIRMAN ROGERS: I just want to add to what I said before, that at the hearings that we have that will deal with temperature effects, and weather and environmental effects and so forth we will want the Thiokol people there.

Yesterday we had a representative from Thiokol there, but he did not have as much firsthand information as we would like, and so we want to be sure at that hearing to have firsthand information and a chronology of all of the events preceding the launch that dealt




with weather and environmental problems.

DR. WALKER: Mr. Chairman, I had an additional question on O-rings, if I might.

The O-rings are not one continuous piece of material. They are bonded in several places.

MR. MULLOY: They are vulcanized together.

DR. WALKER: If the erosion occurred at the location of one of the splices or bonds, would that do you think pose a more serious problem to the seal?

MR. MULLOY: I don't know the answer to that, and I don't know that we have any correlation with erosion at that joint, and I would like to take that as a question and look at that. I really don't know whether erosion at that point would be more critical or whether it erodes more or less in the vulcanized joint.

DR. WALKER: Presumably the erosion is occurring where there are penetrations through the putty, so if the penetration would happen to occur at a joint, then presumably the problem would occur there.

MR. MULLOY: Yes, sir.

Let me take that as a question and look at our test data, whether we have even tested it at a splice joint, and whether that is better or worse in terms of the erosion rate of the O-ring.

CHAIRMAN ROGERS: Thank you, Mr. Mulloy. You




have been very helpful. We appreciate it.

I would like to close the session now today, and as I have said, we will plan to go to Kennedy on Thursday.

I would also like to remind particularly those from the media that the Commission was asked to conduct a calm and deliberate investigation, which I think so far we have managed to do reasonably well. I would, though, suggest that we, because of the press attention, we are not going to continue to be available individually for individual press conferences, and I hope the media will understand that. We are going to provide as much information on a regular basis as we can, probably principally through a spokesman, and therefore we would ask your indulgence and not to intercept our progress in and out of the building.


CHAIRMAN ROGERS: I realize it is a laughing matter. I realize nobody will pay any attention to it.


CHAIRMAN ROGERS: Anyway, it's a good try.

Thank you.

(Whereupon, at 3:40 o'clock p.m., the Commission recessed subject to the call of the Chair.)


February 10, 1986 SESSION | Volume 4 Index | February 13, 1986 SESSION