Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident

 

Volume 5 Index

 

Hearings of the Presidential Commission on the Space Shuttle Challenger Accident: February 26, 1986 to May 2, 1986.

FEBRUARY 26, 1986 SESSION (part 1 of 2)

[887] [Ref. 2/26-1 1 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986.

 

 

 

STATEMENT TO THE PRESIDENTIAL COMMISSION ON THE SPACE SHUTTLE CHALLENGER ACCIDENT

 

 

G. B. HARDY

FEBRUARY 25, 1986

[Ref. 2/26-1 2 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

Mr. Chairman Members of the Commission

I am George Hardy, Deputy Director of the Science and Engineering Directorate at the Marshall Space Flight Center.

Before I relate to you my participation in, and recollections of the teleconference between Morton Thiokol personnel and Marshall Space Flight Center personnel on the evening of January 27, 1986.

- I would like to describe the role of myself and other personnel of the Science and Engineering Directorate with respect to Flight Readiness Assessment for Shuttle flights.

- The primary role of Science and Engineering in this regard is to:

- Participate in Flight Readiness Reviews

- Identify any pertinent issues relative to flight readiness

- Review any issues identified by others (including contractors)

- Assess the rationale for flight and supporting data for any issue

- Provide recommendations to the appropriate Readiness Review Board chairman (if such a Board is in session) or otherwise to Marshall Program Management

[888] [Ref. 2/26-1 3 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

With reference to the teleconference that started at approximately 8:45 p.m. EST on January 27, 1986---

The teleconference between Marshall Space Flight personnel and Morton Thiokol personnel at Kennedy, Huntsville and in Utah --- you have been given a list of all participants at each location.

I would like to identify the personnel at Huntsville from the Science and Engineering Directorate that were supporting me during the teleconference:

Dr. Wayne Littles (Associate Director for Engineering)

Mr. Jim Smith (The Solid Rocket Booster Chief Engineer)

Mr. Robert Schwinghamer (Director of our Materials & Processes Laboratory)

Mr. Bill Riehl (an engineer in the Materials & Processes Laboratory - a non-metallics materials expert)

Mr. John McCarty (Dep. Director of our Structures & Propulsion Laboratory)

Mr. Ben Powers (an engineer in the Structures Propulsion Laboratory - specializing in solid propulsion)

Mr. Keith Coates (in the Office of the Associate Director for Engineering)

 

[Ref. 2/26-1 4 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

Thiokol engineering Personnel in Utah reviewed charts that had been data faxed to the Huntsville and KSC participants Just prior to the beginning of the teleconference.

- The presentations were professional in nature.

- There were numerous questions and answers.

- There was a discussion of various data and points raised by individuals at Thiokol-Utah, at Marshall and at Kennedy.

- A rather full discussion, I would say (Thiokol presented 14 charts and we spent 2 to 2 1/2 hours reviewing and discussing the data and all issues related thereto).

- To my knowledge, anyone who desired to make a point, ask a question, or express a view was in no way restrained from doing so.

 

[889] [Ref. 2/26-1 5 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued)..

 

 

I have heard the teleconference characterized as "heated discussions":

- Penetrating questions were asked

- Various points of view and interpretations of data were exchanged and discussed.

- The discussion was not, in my view, uncharacteristic of discussions of flight readiness issues on previous occasions

 

 

[Ref. 2/26-1 6 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

Thiokol Engineering concluded their presentation with a recommendation that the launch time be determined consistent with flight experience to date (launch with the o-ring temperature ( 53°F).

Mr. Kilminster (Thiokol-Utah) stated that with the engineering assessment he recommended that we not launch Tuesday morning as scheduled.

After a short discussion followed, Mr. Mulloy (at KSC) summarized his assessment of the data and his rationale for flight.

Mr. Reinartz (at KSC) asked me for comments. I stated that I was somewhat appalled (referring to Thiokol's interpretation of some of the data presented with respect to its influence on the joint/seal performance to the issue under discussion). I will discuss this specific data later in this statement. Then I went on to say that I supported the assessment of data presented essentially as summarized by Mr. Mulloy, but I would not recommend launch over Thiokol's objections.

 

[890] [Ref. 2/26-1 7 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

Somewhere about this time, Mr. Kilminster (Thiokol-Utah) stated that they wanted to go off-the-loop to caucus for about 5 minutes. I believe at this point, Mr. McDonald (The Thiokol Senior Representative at KSC for this launch) suggested to Mr. Kilminster that he consider a point I had made earlier, that the secondary o-ring is in the proper position to seal if blow-by the primary o-ring occurred. To the best of my recollection, that was the only comment made on the loop (i.e., during the teleconference) by Mr. McDonald before or after the Thiokol caucus.

The caucus by Thiokol lasted 30-35 minutes. At Huntsville during the Thiokol caucus we continued to discuss the data presented--we were off the loop--around the table-in small groups. I discussed my assessment and understanding of the data with several of my key advisors. None of them expressed any disagreement or differences.

 

[Ref. 2/26-1 8 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

When Thiokol came back on line, Mr. Kilminster reviewed rationale that supported Proceeding with the launch and so recommended. I had no knowledge of who participated in the caucus at Thiokol. It is not typical to ask for a vote count when a senior/responsible official of the contractor presents the company position. What is typical is to assess the rationale for that position.

During the caucus, I had written my evaluation of the data presented as I developed it in my mind and by the discussion that had ensued. (I will review that with you later in this statement).

Mr. Reinartz asked if anyone (on the loop) had a different position or disagreed with the Thiokol recommendation as presented by Mr. Kilminster. There were no dissenting responses. The telecon was terminated shortly thereafter. I have no knowledge of any subsequent events, or discussions between personnel at KSC or at Thiokol on the matter.

 

[891] [Ref. 2/26-1 9 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

As I stated earlier, during the Thiokol caucus, I discussed the data and the issues with several of my key advisors and there was no disagreement among us. I also stated earlier, that there were no dissenting responses when Mr. Reinartz ask if there were any disagreements following Mr. Kilminster's recommendation to proceed with the launch.

I have learned since the 51-L incident that Mr. Ben Powers expressed some concern about the o-ring performance directly to Mr. Smith (the SRB Chief Engineer) and Mr. McCarty (the Deputy Director of the Structures and Propulsion Laboratory). Mr. McCarty is Mr. Power's supervisor. Mr. McCarty has stated to me that he considered Mr. Power's comments along with all the data presented and discussed when he made his input to me.

 

[Ref. 2/26-1 10 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

I would like now to give you a summary of my assessment of the data presented and the conclusion I drew from that data.

I interpreted and assessed the data presented by Thiokol in the context of the accepted performance and operational characteristics of the field joint during the motor ignition transient.

The essential features of these characteristics are:

(1) The primary o-ring moves from the position it has assumed during the leak test to its sealing position as the pressure upstream of the o-ring increases from ambient to approximately 25 to 50 pounds per square inch,

(2) This pressure is imposed on the primary o-ring during the first few milliseconds (100 milliseconds or less) of the ignition transient, and

(3) If a blow-by or failure of the primary o-ring occurs in this timeframe, the secondary o-ring is in its seating Position (this is assured by the leak test pressure).

 

[892] [Ref. 2/26-1 11 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

The issue addressed during the teleconference was the potential for the predicted temperatures to adversely effect the performance of the seals during the ignition transient.

Thiokol engineering presented data on the history of primary o-ring erosion and blow-by at the motor field joints. I concluded that there was no direct correlation with this data and temperature.

- O-ring blow-by was experienced on

- 61-A with the joint at approximately 75°F and on

- 51-C with the joint at approximately 50°F

- There was no o-ring blow-by or erosion on two ground test motors at somewhat lower temperatures than 51-C

- The maximum erosion ever experienced on a primary o-ring was with the joint at a temperature of approximately 70°F

- Subscale hotfire tests have demonstrated a capability of the primary o-ring to sustain erosion of 0.125 inches and maintain pressure with no leakage (this is greater than 3 1/2 times the erosion experienced on 51-C)

 

Ref. 2/26-1 12 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

 

Data on o-ring resiliency was presented and discussed

 

The data showed a decrease response rate of the o-rings with decreased temperatures.

The data presented coupled with o-ring erosion and blow-by history did not indicate that resiliency was a dominant factor in the early part of the ignition transient.

These data points were presented --- 100°F, 75°F and 50°F

- These data would plot a curve that shows that O-rings would not respond immediately to gap opening (due to joint rotation with pressure) if the temperature was below 65 or 70°F.

It was the application and interpretation of these data into our knowledge of the joint sealing characteristics during the ignition transient pressure rise that prompted my statement that I was "somewhat appalled."

 

[893] [Ref. 2/26-1 13 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

Data was presented and discussed relative to O-ring hardness vs. temperature

While hardness is effected by the temperature of the o-rings (durometer of 92 at 30°F vs. 84 at 50°F) .....

Two significant data points existed to assess the effects of the "harder" o-rings on their sealing capability

 

(1) Test data was presented by Morton Thiokol that showed successful sealing with no leakage with the o-rings at 30° F

(2) O-rings with a durometer of 90 was successfully used in the early test phases of the program

 

[Ref. 2/26-1 14 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

My conclusions were:

(1) Blow-by the primary o-ring may occur on 51-L

- It has occurred on flights with joints at approximately 75°F and at approximately 50°F even though it has not occurred on flights and ground test motors with joints over a somewhat wider temperature range

- The duration of blow-by on 51-L may be a few milliseconds longer than 51-C

-The duration of blow-by the primary o-ring is not an issue since it occurs early in the ignition transient while the secondary O-ring is available to seal

[894] [Ref. 2/26-1 15 of 15] Statement to the Presidential Commission on the Space Shuttle Challenger Accident: G.B. Hardy, February 25, 1986. (continued).

 

 

(2) I concluded that the effects of changes in o-ring resiliency and hardness was not a dominant factor in the early part of the ignition transient

- Since any violation of the primary o-ring is expected to occur early in the ignition transient while the secondary o-ring remains in a squeezed position, seated by the leak test pressure, ready to seal ...

and further ...

- Tests have demonstrated the capability of the o-rings to seal at 30°F

 

With my assessment of the data and with inputs from my key advisors on the evening of January 27, I supported Morton Thiokol's recommendation to proceed with the launch.

 

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