Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident


[I1] Volume 2: Appendix I - NASA Pre-Launch Activities Team Report

I. Table of Contents.
II. Signature Page.
III. Summary Narrative.
IV. Charter.
V. Organization.
VI. Definitions of Terms and Acronyms.
VII. Technical Description and Analysis.
A. NSTS Processing.
1. SRB Processing Review Study.
2. SRB Joint Mate Review Team Study.
3. ET Processing Review Study.
4. Orbiter Processing Review Study.
5. Pad-B Activation Review Study.
6. Pad-B Facility Review Study.
7. Ice Team Report.
8. Payload Processing Review Study.
9. Integrated Ground Processing Review Study.
10. Range Support Review Study.
B. Flight Readiness Review Process.
1. Flight Readiness Review Process Study.
C. Pre-Launch Security.
1. Assessment of Kennedy Space Center Security Procedures and Operations Supporting STS 51-L Mission.
VIII. Findings and Conclusions.


[I2] PRE-LAUNCH ACTIVITIES TEAM REPORT [see signature page above].


[I3] III. Summary Narrative.

The Pre-Launch Activities Team was established to organize and conduct a review of the vehicle processing, pre-launch readiness, and security preparations performed for the 51-L mission. This has been accomplished with the results of that review presented within this document.


A. Background.

Within hours of the launch of STS 51-L on January 28, 1986, a multiplicity of panels, teams, sub-teams and working groups were formed to provide information relative to the accident to the Interim Mishap Investigation Board consistent with the NASA Contingency Review Plan. On February 5, the 51-L Data and Design Analysis Task Force was created by the NASA Acting Administrator. The Task Force replaced the interim board, and was directed to support the activities of the Presidential Commission. The Task Force was to proceed with analyses of the facts, circumstances, and design issues surrounding the accident.

The Pre-Launch Activities Team was established to perform the Task Force efforts needed to respond to the needs and interests of the Pre-Launch Activities Panel of the Presidential Commission (see Section IV, Charter).


B. Method of Investigation.

The Pre-Launch Activities Team was organized into three areas of investigation (see Section V, Organization) pursuant to the authority and responsibilities of the Task Force. The three areas of concentration were: NSTS Processing; Flight Readiness; and Pre-Launch Security.

The NSTS Processing sub-team reviewed all aspects of the preparation and build-up of the facilities, GSE and flight hardware involved in processing the 51-L configuration for launch (see Section VII A, NSTS Processing). This review consisted of an in-depth engineering, operations, quality, and safety assessment of the processing documentation with emphasis being placed on identifying all "non-standard" or otherwise significant problems associated with the pre-launch activities.

The sub-team review activity was quite comprehensive, utilizing a large number of individuals, estimated to have been between 800 and 900 people. These review participants represented all levels of the ground processing organization, from engineering management down through the technician ranks. These participants were from both the NASA and the appropriate contractor organizations. Additionally, the review activity had the benefit of flight crew representatives from the NASA Astronaut Office.

The principal reviewers were not those who wrote, performed, or verified the completion of a task during the processing steps. The review generated specific findings from the documentation that could have resulted in harm to flight hardware, flight related GSE or personnel. The review also identified general findings that, although the events were not significant in themselves, were symptomatic of areas requiring improvement in the processing system (see Section VIII, Findings and Conclusions).

The NSTS Processing review found no event which can be characterized as having been a direct contributor to the 51-L accident.

The Flight Readiness sub-team has reviewed the management processes and responsibilities required to certify and maintain readiness of the STS for safe and successful flight operations and specifically how that activity was conducted in preparation for the 51-L mission. This review was accomplished by focusing on how the decision process is structured within the Shuttle Program by documented policy instructions. These instructions include implementing direction to the various program levels and the involved NASA field centers.

Included in the sub-team review was an identification of the necessary inputs from the major Shuttle contractors which certify the readiness of their project elements for a launch. A series of key readiness reviews (e.g., Launch Readiness Review, Flight Readiness Review) and management forums (Mission Management Team) are fundamental to this process. They provide vital status information throughout the program during the pre-launch and mission timelines. All aspects of this information exchange were reviewed, including the generation of necessary project actions, the scheduling of support activities, and the key management participants (NASA, contractor, Air Force) involved in the decision making process.

The detailed report (see Section VII B, Flight Readiness Review Process) also provides a discussion on any variation to the process that was identified to have occurred during the 51-L flight certification process. All documentation pertaining to the readiness certification and the significant action close-out activities, including management approval at each of the review steps, was compiled and assessed. Although the 51-L FRR process was conducted consistent with established procedures, critical SRB flight safety issues were not addressed.

The Pre-Launch Security sub-team review provided a description of the security procedures utilized at the Kennedy Space Center in support of the 51-L mission (see Section VII C, Pre-Launch Security). The procedures reviewed include the Kennedy Space Center (KSC) badging and area permit system; the KSC Unescorted Access and Personnel Reliability Program (UAPRP); law enforcement liaison; mission threat determination; waterway security support; KSC air space restrictions/controls; and work area controls. Also, the review detailed the security support provided to processing operations by EG&G (Edgerton, Germeshausen and Grier) the Base Operations Contractor (BOC), which included the escort of flight hardware and guard protection of facilities.

The sub-team report also details actions taken subsequent to launch. These post-launch activities included the clearing and the closing of security areas, and the impoundment of records. Immediately following the 51-L incident, the BOC initiated a series of area searches to locate and identify items that would be of security interest. A walkdown of the launch area yielded 39 items that were identified and delivered to the debris collection point.

On January 28, 1986, within hours of the STS 51 -L mishap, contact was made with the FBI, USAF (OSI), USSS, NASA Headquarters Security, intelligence-counterintelligence agencies, and local law enforcement agencies for the purpose of coordinating investigative information.

The BOC was directed to review the STS 51-L flow to determine if any events during the processing were relevant to the mishap. No significant information related to the mishap was revealed. The Pre-Launch Security Review determined that the security procedures and operations supporting the 51-L mission were adequate, and that no available information indicates any individual deliberately performed any malicious act which contributed to the 51-L tragedy.


IV. Charter.

A. General Assignment for Pre-Launch Activities Team.

The Pre-Launch Activities Team shall perform, as a priority task, the Task Force efforts needed to respond to the needs and interests of the Pre-Launch Activities Panel of the Presidential Commission. The Team Lead and his deputy shall establish a working relationship with the Commission Panel Leader consistent with the procedures of the Task Force and the Commission.

The Pre-Launch Activities Team shall undertake a critical review and analysis of the NSTS processing. The Team shall assist the Commission in its investigation of the processing and preparation of the NSTS elements so as to determine their impact on the 51-L accident. The Team shall focus on relevant areas of interest such as the following:

1. Processing of flight hardware.
2. Preparation and readiness of support systems such as the launch pad.
[I4] 3. Stacking of the solid motor elements and section.
4. Mating of the NSTS elements.
5. Interface of elements with the Orbiter and supporting structure.
6. Handling of NSTS elements.
7. Pre-launch preparations.
8. Recycle procedures.
9. Inspection and quality control.
10. Deviations and waivers approved in the 51-L procedures.
11. Difficulties encountered on 51-L.
12. Environmental effects on the elements.
13. Mission and payload effects on processing.


The Pre-Launch Activities Team shall undertake a critical review and analysis of launch readiness on STS 51-L. The Team shall assist the Commission in determining if the Flight Readiness Review Process was effective in providing the launch decision for 51-L. The Team shall focus on relevant areas of' interest such as the following:

1. Decision process.
2. Decision panel structure.
3. Means of communication.
4. Process and scope of the data inputs.
5. Timelines of inputs.
6. Distribution of inputs.
7. Evaluation of inputs.
8. Choke points in the process.
9. Internal and external constraints.
10. Potential flaws.
11. Safeguards.


The Pre-Launch Activities Team shall undertake a critical review and analysis of NSTS pre-launch security. The Team shall assist the Commission in determining if security was adequate.


V. Organization.



[I5] VI. Definitions of Terms and Acronyms.


-Auxiliary Power Unit


-Apollo Soyuz Test Project


-Base Operations Contractor


-Certification of Flight Readiness




-Cement vinyl to vinyl


-Data and Design Analysis Task Force


-Dryden Flight Research Facility


- Discrepancy Report


- Edgerton, Germeshausen and Grier


-Eastern Space and Missile Center


-External Tank


-Federal Bureau of Investigation


-Flight Element Assignment Table


-Flight Dynamics Officer


-Flight Readiness Review


-Fixed Service Structure


-Ground Support Equipment


-Holddown Posts


-Impact Limit Line


-Interim Problem Report




-Inertial Upper Stage


-Johnson Space Center


-Kennedy Space Center


-Launch Control Center


-Left Forward Center


-Left Hand


-Loss of signal


-Launch Processing System


-Line Replaceable Unit


-Mobile Launch Platform


-Mission Management Team


-Marshall Space Flight Center


-National Aeronautics and Space Administration


-National Resource Protection


-National Space Transportation System


-NASA Test Director


-Operational Intercom System


-Operations Manual


-Operations Maintenance Instruction


-Operations and Maintenance Plan


-Operations Maintenance Requirements Specification Document


-Orbiter Maneuvering System


-Orbiter Processing Facility


-Office of Special Investigation


-Payload Ground Handling Mechanism


-Payload Processing Facility


-Problem Report


-Program Requirement Change Board Directive


-Power Reactant Storage and Distribution


-Processing Support Plan


-Quality Control


-Reaction Control System


-Radio Frequency


-Rotation, Processing and Surge Facility


-Range Safety Officer


-Rotating Service Structure


-Return to Launch Site


-Shuttle Processing Contractor


-Standard Practice Instruction


-Solid Rocket Booster


-Solid Rocket Motor


-Space Shuttle Main Engine


-Space Shuttle Vehicle


-Tracking and Data Relay Satellite




-Thrust Vector Control


-Unescorted Access and Personnel Reliability Program


-Universal Documentation System


-Uninterruptible Power Supply


-United States Secret Service


-Vehicle Assembly Building


-Vertical Processing Facility


-Work Authorization Document


VII. Technical Description and Analysis.

This section contains the results of the technical reviews and analyses that were conducted in support of the Pre-Launch Activities Team Review. The section is divided into three subsections (Section VII A. NSTS Processing: Section VII B, Flight Readiness Review Process; Section VII C, Pre-Launch Security). Significant findings resulting from these reviews are included and discussed in Section VIII, Findings and Conclusions. These findings are directly relevant to the 51-L mission, or are considered to be of particular interest in the attainment of more efficient and disciplined operational practices and therefore are emphasized for specialized attention.

The following sub-sections elaborate on the efforts of each sub-team and offer a summary of their activities and results. For completeness, detailed documentation is provided, in the form of appendices, which thoroughly present the review method used by the various sub-teams and the findings of those reviews.


A. NSTS Processing.

The National Space Transportation System (NSTS) Processing sub-team has reviewed the totality of the flight hardware processing activity associated with the 51-L mission (External Tank, Solid Rocket Boosters, Orbiter and payload). Because of the indicated possible leak in the 51-L right hand Solid Rocket Booster (SRB), a separate panel was formed to review the field joint mating process conducted at KSC during the SRB stacking operation. The flow was analyzed both as the processing of the individual flight elements prior to mating, and of the integrated configuration after mating. Additionally, the team reviewed the operational documentation associated with those systems (MLP/Pad GSE, Facility Systems) that constituted a primary interface with the Right hardware.

Furthermore, the activation and subsequent performance of Pad B during the 51-L launch was examined for inadequacies or anomalies. The activities of the Range Support (DOD) and the Ice/Frost Teams were reviewed and documented as ingredients of the pre-launch operations.

The NSTS Processing sub-team was divided into various functional groups, all with discipline representation from Engineering, Operations, Quality and Safety to accomplish this extensive review. The review was comprehensive in the manner in which operational documentation was investigated for irregularities related to the launch of STS 51-L. The sub-teams developed and analyzed data on how each anomaly in the flow might have been a factor in the incident. As processing or procedural anomalies were identified, recommendations as to proposed corrections were formulated and documented.

The sub-teams relied on the broad cognizant technical community, with group membership from both the NASA and the participating contractors to accomplish a thorough critique of the 51-L pre-launch activities, including analyses of existing systems processing practices. The sub-teams typically utilized an executive panel, representing each of the major functional review groups, to finalize the overall examination into categorized problems or [I6] concerns of significance. The results of those independent reviews are summarized as follows:


1. Solid Rocket Booster (SRB) Processing.

The Solid Rocket Booster (SRB) Processing Team reviewed all operations for flight hardware processing and associated Ground Support Equipment (GSE). This was from arrival of the first segment of the Solid Rocket Motor thru buildup, stacking, and then closeouts prior to the Space Shuttle Vehicle transfer from the VAB to Pad B. The teams reviewed all Work Authorization Documents that were associated with the buildup of both the left-hand and right-hand SRB's. This review covered the receipt of segments in the Rotation, Processing and Surge Facility (RPSF), and their subsequent offload, inspection, aft booster buildup, segment stacking in the VAB, and closeouts of the SRB's prior to VAB rollout.

Operations Manuals/Operations Maintenance Instructions (OM's/OMI's) were reviewed for technical content, organization, clarity, and proper incorporation of deviations. Operations Maintenance Requirements Specification Document (OMRSD) requirements were examined to make sure they were properly, recorded in associated tasks. Tasks, job cards, and OMI's were reviewed for the presence of appropriate stamps, IPR's and PR's. deviations worked, and engineering calculations. This review determined if the work was specified correctly, was completed successfully, and if the documents met proper standards. Special emphasis was placed on identifying all non-standard work or otherwise significant activities, including off-nominal observations during SRB processing. This review involved over 100 people from all disciplines of engineering, operations, quality, safety and the mechanical/electrical shops. The results were reviewed by an executive panel for completeness and accuracy.

In addition, the study provided specific documentation covering a complete description of the activities performed in the areas of:

SRB Stacking: Review of processing prior to STS 51-L in which O-ring damage was observed during the post-flight disassembly, process.

SRB Destacking: Investigation of the STS-9 SRB destacking for any anomalies in the O-rings, joint putty, and the overall field joint.

Four "Off-Nominal" observations were documented as follows:


a. Left Forward SRM Segment Incident.

During unloading operations of the left forward SRM segment on November 7, 1985, receiving inspection indicated defects requiring repairs to the tang. After repairs to the tang were completed, the next operation involved removing the lifting ring attached to the clevis. Approximately 85 seconds into the lifting operation, a sharp bang was heard and an emergency shutdown was initiated., It was noted that the lifting ring had shifted approximately two inches above the clevis. A problem report was prepared. appropriate personnel notified, photos taken of the suspected damaged areas, and an incident report filed that indicated a failure to follow established lifting procedures.


b. Replacement of Damaged Segment.

A decision was made by the design center (MSFC) not to use the damaged segment on STS 51-L. This segment was replaced with another LFC segment slated for STS 61-E. When segments are loaded with propellant at the Morton-Thiokol plant, they are poured in pairs from the same lot of propellant. Burn rates vary between lots, and for this reason, matched segments of one lot are always flown on opposite SRB sides so that the thrust is balanced. Consequently, the matched mate on the right hand SRB was also replaced. The two segments that replaced them were also a matched pair. This matched pair was chosen based on the fact that its bum rate and predicted thrust performance were well within the predicted bum rate and thrust performance of the rest of the SRM segment set. Also, the materials used in the propellant for the substituted matched pair were from the same material lot as for the other segments. This change was accomplished via the Level 11 PRCBD.


c. Water Leakage From Right Aft Center Segment Cover on 51-L.

On December 5, 1985, at approximately 1300 hours, the right aft center segment for the 51-L stack was positioned outside the north door of the VAB before being moved into the VAB for stacking.

Because of tensioning problems with the right aft booster holddown studs, the left-hand Solid Rocket Booster segments were stacked first. This resulted in the right aft center segment being left outside the VAB north door for approximately 34 hours.

At approximately 2000 hours on December 5, 1985, after a severe rainstorm, water was observed leaking from the lower segment cover. The top segment cover was in place, secured around the circumference of the segment with a bungee cord, and tied down at four points with rope. All seams in the segment cover are sealed with CVV (cement vinyl to vinyl) for waterproofing. The lower segment cover is secured around the bottom of the segment with a bungee cord only.

A problem report was written stating: "Segment cover leaking water (from rain) through center and out bottom cover. Damage, if any, unknown. Segment was located just outside of VAB door during heavy rain." Morton-Thiokol Launch Support Services was contacted. It was decided that the water would have no detrimental effect on the segment. The PR, therefore, was dispositioned to wipe off top and bottom surfaces with clean, lint-free cloths, and to wipe the bottom surface before stacking and the top surface after stacking. This was due to a lack of easy accessibility to the top surface before stacking.

According to the technicians who wiped off the top, water did exist on this surface. However, this is not conclusive proof that the top cover leaked, because the VAB roof also leaks during heavy rains. This could also be a reason for water on the top surface. Another possibility for water draining from the bottom cover is that rainwater traveled down the outside surface of the segment and drained into the bottom cover. For this reason, procedures and covers used to weatherproof both ends of the segments will be investigated and the VAB roof leaks will be reviewed.


d. Holddown Post #2 Stud.

During pre-tensioning of the right-hand booster holddown post studs on the right side, holddown post #2 did not meet the minimum OMI stretch requirements of 0.0599 inch. It only reached a stretch of 0.0570. A problem report was written, with no constraint to stacking segments on the right-hand side. Reevaluation of holddown post #2 stud was to be performed after completion of right-hand segment stacking.

After completion of right-hand segment stacking, re-tensioning of holddown stud #2 was performed. This time the maximum stretch obtained was only 0.0559, which again did not satisfy the requirement of a minimum 0.0599. The PR was then dispositioned to replace the stud. During detension, however, the frangible nut could not be unseated, due to binding between the threads. In order to break the nut loose, the pressure on the Biach tensioner was raised to 12,800 psig. At this time, it was noticed that hydraulic fluid was leaking from the upper housing of the tensioner unit. A Discrepancy Report (DR) (later upgraded to Problem Report - PR) was written against the tensioner, which was then replaced with another unit per disposition on the original PR. Tensioning of the original stud was performed and again the stud failed to achieve the minimum stretch requirement with a. measurement of 0.0559. Finally, the stud was replaced with a new stud, and after two pulls a stretch of 0.0604 was achieved, which satisfied the minimum stretch requirement. The PR was then closed. The original Biach tensioner was found to have a damaged O-ring seal and was repaired per the DR.

The conclusion of this study was that no operations were found which contributed to the 51-L mishap. However, findings were [I7] documented indicating specific areas requiring improvement in future operations. These findings are consistent with the general findings contained in this report.


2. SRB-Joint Matt Review Team Study.

The SRB joint Mate Review Team was formed when launch and ascent film review indicated a possible leak in the STS 51-L right hand SRB.

The Team conducted a detailed review of the planning (OM) and requirements (OMRS) documents which controlled performance of the SRB right hand aft field joint assembly for STS 51-L. It was concluded that the procedures were properly prepared, and the requirements imposed by the design agency (NASA/MSFC) were incorporated and were properly approved and released for use. It should be noted, however, that even though the OMRSD was followed during the joint mate the procedures did not prevent flat-on-flat.

The actual planning documents (OMs) and authenticating documents (job Cards and PRs) used in performing the SRB right hand aft field joint mate operations on STS 51-L were examined. The team also examined the actual planning and authenticating documents used to inspect the clevis and tang joints of the two segments during receiving inspection. It was concluded that the required operations and inspections were conducted in accordance with the approved, released documentation. Except for minor discrepancies, all required technician, contractor quality inspector, and NASA quality inspector stamp authentications were present.

The Team reviewed the background and experience of the technicians, inspectors, and supervisors who were involved with the joint mate operation. It was determined that a personnel were experienced in the operations being performed, having participated in a number of previous SRB stacking operations. The least experienced technician had participated in five previous launch vehicle stacks (10 SRBs), while many had participated in 14 launch vehicle stacks (28 SRBs). There were no personnel who had never participated previously in joint mate operations. It was concluded that the joint mate operations were performed by adequately experienced personnel.

A sub-group of the Team interviewed a majority of the technicians and inspectors who participated in the STS 51-L right aft field joint mate. These interviews, while providing interesting supplemental commentary, did not bring to light any data or information not already identified by other team investigations. In general. the only factor which permitted any of the interviewees to remember this joint mate was the fact that the rounding tool was used. It was concluded from the interviews that the processing of the STS 51-L right aft field joint mate was routine, with no noteworthy abnormalities, variations, or unusual circumstances.

All major process changes incorporated in the field joint mate operations since STS-1 were reviewed. The most recent change, one involving zinc chromate putty lay-up patterns and thicknesses, was introduced on STS 61-A. SRBs incorporating that change have flown on STS 61-A, 61-B, and 61-C. Some O-ring anomalies were experienced on 61-A and 61-C. All other joint mate process changes were introduced earlier and have flown successfully several times. It was concluded that there were no process changes incorporated for the first time during STS 51-L joint mate operations.

The Team reviewed the joint mate processing history and determined that there were no processing variations which had not been experienced on previous SRB stacking operations. The stacking sequence normally alternates assembly between the left-hand and right-hand SRB. However, because of the tensioning problem on the right-hand SRE holddown post, the two aft segments were installed on the MLP and then the left-hand SRB was stacked. While this is not the normal stacking sequence, it had been used in four previous launch vehicles. The time required to complete joint mate and leak test was average when compared to SRB segment processing times for the previous five launch vehicles, and the Circumferential Alignment Tool had been used on five joints prior to STS 51-L. It was concluded that variations in sequence and technique used in STS 51-L joint mate operations were typical of previous program experience.

The Review Team concluded that processing of the STS 51-L right hand aft field joint was conducted in accordance with the established, approved procedures, and that there was nothing in the processing which is believed to have contributed to the STS 51-L flight failure.


3. ET Processing Review Study.

The External Tank (ET) Processing team reviewed the standalone processing, including associated GSE, from ET (ET-26) arrival on dock at KSC until it was ready for Orbiter mate. As-run work steps for all tasks were reviewed in detail, to determine if there were any problems which could have been related to the STS 51-L accident, or which could have contributed to loss of life or significant damage to flight hardware. The team reviewed 168 stand-alone Work Authorization Documents (WADs).

During the stand-alone processing of ET-26, there existed one unexplained anomaly which, however, was considered insignificant. This involved a broken paper integrity seal on an aft restraint. The safety margin was sufficient to restrain the ET, and its integrity was not violated. The Problem Report was closed. The process will be changed so that lead wire seals can be installed, the contraction of the aft restraint can be limited, and mechanical stops can be installed on the rod/turnbuckle. (See Section VIII, Findings and Conclusions, page 1-15.)

The review performed by the ET Stand-alone Processing Review Team concluded that ET-26 was properly processed for the flight of STS 51-L during stand-alone operations, and met all OMRSD requirements.

The Review Team found nothing which is believed to have contributed to the STS 51-L flight failure.


4. Orbiter Processing Review Study.

The Orbiter Processing Team was organized on January 29, 1986, and held its first meeting on the following day.

The team's investigation covered the processing of Challenger (OV-099) from the time of landing at DFRF at the conclusion of mission STS 61-A, to the time of mate operations with the ET in the VAB, with a concentration on "off-nominal" work. All Work Authorization Documents (WADs) were reviewed in-depth, including WADs used during the countdown operations. In addition to the WAD review, the team also reviewed all 51-L Orbiter systems data from call-to-stations (CTS) for the launch countdown through ascent loss of signal (LOS). The 51-L investigation paper review did not reveal any significant Orbiter, MPS, or launch countdown findings relevant to the mishap. However, all findings have been documented in the Orbiter report to ensure follow-on corrective action. Listed below are the conclusions from this review.


a. Spare Parts.

There are insufficient spare parts to maintain the Orbiter fleet in an operational configuration. Therefore, the practice of parts cannibalization has been resorted to in order to meet manifest demands. The lack of adequate spare parts creates major perturbations to manpower requirements, not only in the work required, but in the documentation and workarounds associated with cannibalization of parts and the multiple installation and removal of components from one flight vehicle to another. This process also increases the damage exposure to electrical connectors, wire bundles, ducts, and other items in the vicinity of the target part. Many critical items are one or two of a kind for the entire fleet such as ferry tail cone, ferry elevon actuator locks, engine heat shields (two sets), and crew module MPS meters.


[I8] b. Manpower Shortage.

With four vehicles (at moment of launch), four firing rooms, two bays in the Orbiter Processing Facility, two launch pads, Edwards AFB/DFRF recovery responsibility, and Vandenberg AFB integration responsibility, some personnel work multiple jobs and occasionally very long hours. The shortage of personnel in certain areas has occasionally led to the practice of placing new or less experienced personnel in positions of responsibility. The manpower shortage also leads to the standard practice of personnel on console supporting multiple functions (primarily during slack time). This practice was considered a contributing factor in the 17-inch LH2 valve incident that occurred during this countdown (see Section VIII. Findings and Conclusions). The manpower shortage may be a contributor to the decreasing quality of paperwork at KSC in that new personnel do not have the benefit of experience or extensive training in paper procedures. Additionally, some experienced personnel are taking shortcuts to get more done in the same amount of time.


c. KSC Documentation.

Areas of unclear documentation were noted during the document review. Instructions in WAD's are frequently not clear or imprecise. The ONIRSD system is very difficult to paper track with respect to auditing requirements. The OMP and PSP, which are the KSC supporting documents to the OMRSD system, are often incorrect in that Deviations (Dev's) and Revisions (Rev's) are incorporated between the publication of one document and another. Finally, the OMP is not a closed loop system and is sufficiently complex such that the cognizant systems engineer is the only person who knows the full status of OMRSD requirements.


d. Lack of Documentation System Discipline and Education.

Of approximately five thousand documents evaluated, a large percentage were found to be incorrectly executed. The discrepancies are generally minor in nature, such as incorrect signatures, missing signatures, lack of QC, incomplete rationale for closure, etc. However, these discrepancies point to a problem involving lack of discipline and education regarding procedures and requirements. An across-the-board training program is required to educate personnel at all levels on WAD preparations, processing, verification, and closure. The SPI (Standard Practice Instructions), the guide for preparing and performing paperwork, needs to be re-evaluated. upgraded if necessary. then enforced. Attention to detail must be re-emphasized.


5. Pad-B Activation Review Study.

The Pad-B Activation Review Team was established on January 29, 1986, and a preliminary plan developed on that date to describe the approach for carrying out the investigation. The last operational use of Launch Complex 39B prior to STS 51-L was for the launch of the Apollo Soyuz Test Project (ASTP) Mission in July of 1975. The pad was then down-moded with minimum maintenance until start of modifications for the Shuttle Project in August of 1978. Upon completion of a series of fixed priced contracts to perform the Shuttle modifications and activate the facility for Shuttle use, the pad was turned over to the SPC contractor for sustaining engineering in December 1985 (the SPC, Lockheed Space Operations Company, had been performing engineering and checkout functions to bring the pad on-line since award of the SPC contract in October 1983).

The team's investigation covered the Pad-B "As Run" activation tasks from ASTP in 1975 to December 13, 1985, when the TDRS was brought to the pad. The team effort concentrated on all "off-nominal" work. Necessary follow-on Pad-B modifications have been outlined and documented (see Section VIII, Findings and Conclusions).

The Review Team found nothing which is believed to have contributed to the STS 51-L flight failure.


6. Pad-B Facility Review Study.

The Pad-B Facility Review Team was organized on January 28, 1986, and pad systems walkdowns occurred on January 28, 1986 through January 31, 1986.

The purpose of the review team was to determine individual pad systems' conditions and anomalies after the launch of STS 51-L. All launch damage and launch measurement data for LC-39B ground systems anomalies covered in the report were considered normal with five receiving special attention. The first was the formation of large quantities of ice on pad facilities because of the freezing temperatures, winds, and flowing water associated with the Freeze Plan. Along with this, a concern was developed for potential effect of freezing temperatures on pad systems performance. The second anomaly was the loss of the springs and plungers on the SRB holddown posts blast shields. The third item was the failure of the gaseous hydrogen vent umbilical arm to latch. The fourth and fifth anomalies (considered minor) were a crack in the MLP-2 blast deck and the loss of bricks from the flame trench. A summary of these anomalies follows:


a. Freezing Weather Conditions.

The existing "Freeze Plan" required that certain water and Firex systems be left flowing slightly for freeze protection. That, combined with the weather conditions, resulted in an ice buildup on areas of the Launch Pad. This created a concern that the ice could become debris during liftoff, which could potentially damage the Orbiter thermal protection system. After reviewing films of ice at liftoff, reviewing Pad B walkdowns damage lists, and assessing launch systems measurement data, the Pad B Facility Team concluded that the ice did not appear to have caused any damage as debris; however, camera view angles do not provide 100% coverage of all areas. While the weather conditions may have affected the shock absorber fluid on the ET GH2 vent arm deceleration cylinder, performance of other ground systems did not appear to have been significantly affected. One exception was the ET nose cone purge, which allowed the nose cone temperature to drop to 10°. This situation was waivered real time and was not found to be related to the 51-L mishap.

The ice formation problem will be corrected by a redesign of the pad water systems, with appropriate corrections to the Freeze Plan. The effects of temperature on systems performance will be carefully reviewed and any necessary corrections to hardware or operational procedures will be undertaken.


b. Loss of Plungers and Springs - SRB Holddown Posts.

SRB holddown posts (HDP) performance and damage was nominal except for the loss of the four plungers and springs (modifications to holddown posts effective for STS 51-L) that aid in the closure of the blast shields for posts #3, #4, #7 and #8. Only one spring and two plungers have been found; however, searches are ongoing outside the pad perimeter. These (North) HDP receive direct SRB plume impingement that reduce service life; therefore, they require protection from the SRB heat to permit reuse of the HDP shoe and spherical bearing. Posts #1, #2, #5 and #6 do not have blast shields because the SRB blast does not impinge on these posts. After a detailed analysis and assessment of the kick spring anomaly, the Pad B facility Team conclusion is that:

(1) The kick springs were in place until the hood (blast shield) rotated to less than 57° from horizontal. This occurred (using film data) for post #7 at .854 seconds, post #3 at .831 seconds, and posts #4 and #8 at least .800 seconds after T-0; i.e., the springs and plungers cannot physically clear the retaining tube until the hood angle is less than 57' from horizontal.

(2) Camera coverage between the vicinity of the springs and vehicles shows no debris until loss of camera.

(3) Analysis of the one spring sample shows that it experienced low heat and slight Al2O3 deposits, indicating that the spring [I9] remained in the tube until impingement was essentially gone (3.5 seconds, vehicle altitude 65').

(4) Blast loads occurred in the vicinity of the springs at 2.09 seconds; when the vehicle altitude was approximately 21 feet.

(5) Al2O3, deposits infer that the plungers remained in the tube until a minimum of 18.5' to 65' of vehicle rise (approximately 2.0 seconds to 3.5 seconds vehicle flight time).

It was concluded from this analysis, no damage to the Orbiter resulted from holddown post debris.


c. ET GH, Vent Umbilical Arm.

The ET GH 2 vent arm performance (including system timing) was nominal except that the arm did not latch. Post-launch inspection also revealed a broken haunch pivot pin. Film coverage indicates that the disconnect, vehicle clearance, and rotation of the arm were nominal, and that no recontact occurred.

The Pad B Facility Team feels that the colder environment probably affected the shock absorber fluid viscosity and slowed the vent arm during the last few feet of travel, resulting in a lack of force needed to latch the arm. Failure analysis of the broken pivot pin and additional testing of the shock absorber for low-temperature conditions is required. The necessary design changes will be incorporated and adequate testing of the total GH2 vent arm system will be accomplished to ensure successful operation of the arm and latch system.


d. Blast Plate Crack and Loss of Flame Trench Brick.

Two minor anomalies that caused concern (although similar anomalies have occurred on past launches) are: A crack in the MLP-2 blast deck, which occurred at approximately 4 hours and 30 minutes after launch; and loss of bricks in the flame trench.

The MLP blast deck cracks are caused by built-in stress during construction, structural detail, and thermal cycling from launches. The cracked area will be removed and the deck repaired by welding in new material.

Previous fire brick loss also occurred on the first Shuttle launch from Pad 39A. This resulted from poor bonding which is caused by exposure to water over the time period from initial installation to launch (over 20 years). The missing brick will be repaired using refractory concrete.

The Review Team concluded that the launch system anomalies that occurred at the launch of STS 51-L were not contributors to the in-flight failure.

In order to assure future launch system performance, a total review of the facility systems will be accomplished by the systems teams. This review will encompass requirements, design, systems assurance analysis, and testing and will recommend any changes required to assure future launch systems success.


7. Ice Team Report.

Members of the Ice/Frost Team made three assessments of the icing conditions on the FSS/RSS/MLP deck and Pad B apron areas during the STS-51-L pre-launch activities. Due to a drop in temperature to below freezing during the preceding day and night, the Freeze Protection Plan, last used for STS-51-C on January 24, 1985, was implemented to protect the various facility systems. Two actions within the plan were intended to limit the ice debris which potentially could cause damage to the Shuttle Vehicle during launch.

The first action involved adding approximately fourteen hundred gallons of antifreeze to the overpressure water troughs. The water capacity in both SRB exhaust holes is 6,580 gallons. The resultant antifreeze to water ratio was calculated to be 21.3 %. According to the manufacturer's specifications, the solution is protected against freezing down to an ambient temperature of 16'F. The second action involved the draining, where practical, of all water systems. Several systems such as Firex, Deluge, and emergency shower and eye wash were not drained. These systems were opened slightly and allowed to trickle into drains. The trick ling water was found to cause drain overflows. High wind gusts spread the water over large areas and it then froze.


a. First Assessment.

After call-to-stations the Ice/Frost Inspection Team observed the icing conditions and notified upper management. A decision was made at that time to send the Ice/Frost Team to the pad for an assessment of the facility icing conditions. The team arrived at the pad at 0130 hours and remained for approximately one and one-half hours. The Pad apron, MLP deck area, each level of the FSS and the 215-foot level of the RSS were inspected. Ice ranging in thickness from 1/8 to 3 inches was observed on the Pad B apron, MLP deck, FSS, and RSS. Access to all the slide wire baskets was hazardous due to icing on the grating. The ambient temperature was approximately 29 degrees F.


b. Second Assessment.

The Ice/Frost Inspection Team made its usual inspection during the built-in hold at T-3 hours. The team arrived at Pad B at 0654 and departed at 0844. The team was augmented by several facility personnel to aid in the removal of ice from the water troughs. The ambient temperature was between 26.1 degrees and 30.1 degrees F.


(1) Orbiter

Frost was present on the Shuttle main engines. Butcher paper on a single RCS stinger was torn on the aft nozzle and completely missing from one of the forward nozzles. This condition was observed during the post detanking inspection on January 27, 1986. No tile anomalies were observed on the Orbiter lower surfaces, OMS pods, aft heat shield, tail, nose, and control surfaces. No leaks were detected on either the LH2 and LO2 umbilicals.


(2) Solid Rocket Boosters

Icicles had formed on the -Y-Z quadrant of the LH SRB on all stiffener rings and the ET attach ring. Icicles were also present on the stiffener ring drain holes and the bottom ring of the aft skirt. Most of the icicles on the aft skirt were removed during this inspection. Patches of sheet ice had formed on the LH SRB aft booster case and aft skirt on the -Y side and in the -Y-Z quadrant.


(3) External Tank

A light layer of frost was observed on numerous areas of the External Tank. Ice/frost, in amounts typically observed during previous rankings, had accumulated in both LH2 feedline bellows and both LH, recirculation line bellows. Ice/frost had accumulated in all the LO2 feedline bellows and between the feedline and supports. Although a piece of foam had been removed from the + Y bipod ramp during an RSS platform incident, no ice/frost was visible in this area.


(4) Facilities

Ice in the troughs had thickened and was found to be solid. All secondary troughs except the northernmost one in each hole had ice. An attempt to use a water jet from a Firex hose to break up the ice was unsuccessful. The "shrimp net" was employed to break up the ice and remove it. Approximately 950/o of the ice was removed. The ice and unfrozen antifreeze solution was measured using an infra-red pyrometer and found to have a temperature between 14 degrees and 16 degrees F. The two troughs on which the fire hose was used measured 23 degrees F. The infra-red pyrometer measured the MLP deck surface temperature as 23 degrees F. (These readings have been corrected for the IR pyrometer transient error.)

On the FSS the quantity of ice had increased but the overall extent of icing was generally the same. In most cases, sheet ice was firmly adhered to the structure. Icicles could very easily be .snapped" off. Water continued to trickle down the facility, including the RSS.


[I10] c. Final Assessment.

A smaller crew returned to the Pad between 1030 and 1055 a.m. to assess icing conditions on the MLP deck and remove any loose ice. The ambient temperature was between 34.8° and 36.2°F. MLP deck ice had started to melt in areas receiving direct sunlight (between the LH SRB and FSS). Icicles had begun to fall from the upper FSS levels. Ice cube size pieces of these icicles were found within 10 feet of the LH SRB exhaust hole. The west MLP deck was swept clean of ice/icicles. The water troughs were checked and found to be forming ice, which was again removed using the "shrimp net." During the three inspections, only the two South primary troughs remained ice free. The team departed the pad at approximately T-20 minutes.

Most of the icicles on the aft skirt of the LH SRB were removed during the inspection. All of the frost spots, frost lines, and waivered areas of ice on the ET were typical of amounts seen on previous missions and did not violate any Launch Commit Criteria.

Approximately 95076 of the ice in the water troughs was removed. Between 1030 and 1055 a.m., during the final inspection, loose ice on the MLP deck was removed and ice had begun to melt in areas receiving direct sunlight.

Post-flight photographic analysis showed that falling ice from the FSS/RSS did not damage the Orbiter tiles at liftoff.


8. Payload Processing Review Study.

The Payload Processing Review Team reviewed STS 51-L payloads processing from arrival of flight hardware at the Vertical Processing Facility/Payload Processing Facility (VPF/PPF) through launch to assure all activities were performed per approved procedures, that procedure performance was properly verified/documented, and to identify any discrepancies or anomalous conditions that may have occurred during the flow.

An in-depth review of the "as-run" documentation for payload processing installation performed at Kennedy Space Center was conducted from February 10 through March 12, 1986. This review consisted of a page-by-page, line-by-line review of work documentation, test operations procedures, and documentation of unplanned events (problems, deviations, waivers) for all critical activities. These include tasks associated with major integrated test operations, payload flight hardware handling and installation, payload ordnance operations, payload fueling, and payload inspections. Each document was examined for accuracy, completeness. satisfaction of requirements, documentation, understanding and approval of deviations and unplanned events, and quality control/engineering certifications of work complete.

The review team found no indication or evidence from this review of any payload element involvement in, or contribution to, the STS 51-L mission in-flight failure.

The review team found no waivers or deviations associated with payload element processing that had potential safety-of-flight implications.


9. Integrated Ground Processing.

The Integrated Ground Processing Team reviewed 1,453 operating documents containing the work records associated with the 51-L integration of the Orbiter with the stacked SRB's and ET, the processing of the integrated vehicle and payload at LC-39B, and up to the beginning of the 51-L launch countdown. The review was conducted by teams and the results reviewed by an executive panel for completeness and accuracy. This review involved over 130 people who inspected each document to determine that the work was specified correctly, was completed successfully and that the documents met proper standards. Nonstandard activities were identified and researched.

This study concluded that no operations were found which contributed to the STS 51-L mishap. However, findings were documented which indicate there are specific areas requiring improvement in future operations. These findings are consistent with the general findings contained in this report.

In addition, the study provided specific documentation covering a complete description of the activities performed in the integrated ground processing. Included in this description are hour-by-hour schedules and a weather summary for each period of time. As a special topic, launch weather summaries are provided for a STS launches. What follows represents results of the Integrated Ground Processing Team review.


a. Pad-B Activation.

Pad-B was not fully activated when it was required to support the STS-51-L flow. Several support systems were not completely verified; e.g., LPS wideband lines, hazardous gas, fire and leak detection system, UPS-40 power system. These and other Pad-B issues caused scheduling perturbations and required occasional operational workaround.


b. Work Authorization Documentation Audit.

The Integrated Ground Operations report identifies cases where WAD problems occurred on critical vehicle or vehicle-related GSE systems.

The review has found that the ability of the work control documentation system to guarantee proper real-time execution of tasks and their subsequent traceability is inhibited by factors that must be identified and corrected by KSC management. Training must be adequate to ensure that all workers are able to comply with the regulations which govern the "paperwork system." Additionally, it appears that a re-emphasis of the necessity for proper discipline is in order. It is further recommended that, if possible, the system be made more "user friendly" providing that the proper level of rigor can be maintained.


c. Hazardous Operations.

Nine items were identified which document the performance of hazardous operations without proper safety procedures.

A re-emphasis of proper training and worker discipline as applicable to the performance of hazardous operations is required. The events which became "findings" of the Integrated Ground Processing Team resulted from failures to adhere to standard definitions of what constitutes a hazardous operation and from failure to provide for adequate documentation and safety coverage of such operations. It is the belief of the Team that the regulations in existence are sufficient to provide for safe operation, but need to be uniformly understood, applied, followed, and enforced.


d. Workmanship.

In general, workmanship was found to be of acceptable quality. However, there were some instances of undocumented problems, unreported damage, and poor work practices indicating that personal responsibility and discipline are sometimes inadequate. Management must reinforce its stand on the importance of flight vehicle and personnel safety.


e. Workload.

At times, resources, both hardware and personnel, were inadequate to cover operations at Pad-A and Pad-B simultaneously. In general, the continuation of STS 61-C activities well into the STS 51-L timeframe diverted personnel from the STS 51-L operations and also caused major schedule perturbations to the STS 51-L flow.


An evaluation of the effect of workload should be made to determine if this factor is a contributor to the findings of this report. Problems found with paper, workmanship, lack of thorough understanding of requirements and configuration may well have their roots in the overloading of the available workforce.

External factors such as late requirements also affect the efficient utilization of the available workforce, as well as inducing schedule perturbations that tend to exacerbate the problem of improper documentation discipline.

In addition, the work was generally found to be technically complete and met demanding schedules but sometimes at the expense of complete documentation.


[I11] 10. Range Support Review Study.

The Range Support Team was organized on February 21, 1986, to perform an independent review of Eastern Space and Missile Center (ESMC) activities during STS 51-L.

The Range Support Team review included an evaluation of Program Support Management, Support Requirements Documentation, Range Safety Activities, Instrumentation Configuration, and Contingency Operations following the mishap.

Key duties of Program Support Managers for Shuttle missions consist of preparing Staff Summary Sheets, Network Readiness Certificates, presentations at Flight Readiness Reviews and other duties from L-3 weeks to L + 30 days. During the STS 51-L mission, all events leading up to launch progressed on schedule with no apparent problems. The most significant concern uncovered by the review team is that Program Support Managers' level of involvement and degree of understanding of the documentation flow needs to be improved.

The Universal Documentation System (UDS) provides a common language and format for effective communication between the user. lead range, and support agencies. Use of the UDS is mandatory for National Ranges. An STS peculiar documentation system has been implemented at the ESMC that significantly modifies the UDS. This was reportedly done at the insistence of NASA due to the dynamic nature of the program and the need to automate the documentation system. For STS 51-L, the review concluded that all required documentation for support of the mission was timely and complete. The most significant concern uncovered by the review was that the present STS document concept, using the automated system, makes it difficult if not impossible. to develop an audit trail of changing mission requirements, support capabilities and range commitments.

Range Safety activities proceeded normally throughout the final countdown and launch of STS 51-L. At the time of the explosion, the Range Safety Officer (RSO) determined that the range safety displays did not provide useful information. It was not apparent whether a radar was tracking a single object or alternately tracking a variety of debris objects. As a result, the RSO could not use his displays to make any safety decisions. It was from the video source that RSO decisions were made. After arm and destruct functions were sent to the SRBs, the NASA/JSC Flight Dynamics Officer (FDO) indicated to the RSO that they (NASA/JSC) had lost the TM downlink and all communication from the Orbiter. At that time, the RSO told the FDO that the External Tank had exploded. Neither the FDO, nor apparently anyone at the JSC control center, were aware of the explosion prior to this time. A point of concern here is necessary to highlight: If the RSO had not had any video information available, destruct functions would not have been sent. For the 51-L situation, this could have resulted in increased risk from the stabilized SRBs to such inhabited areas as Titusville.

A review of the instrumentation in support of STS 51-L indicated that it was configured to support as required. Instrumentation systems satisfied requirements during the launch phase and responded well to the mishap. Preparations had been planned for contingencies such as Return to Launch Site (RTLS); however, no plan had been prepared for a catastrophic failure of the nature of STS 51-L. This, for example, may have contributed to the delay in dispositioning rescue aircraft into the impact area following the mishap. Instrumentation sites relied on experience with malfunctioning missiles to acquire and track different portions of debris. Post-operation analysis of radar and optics data were combined to give a good estimate of the impact location of major pieces of debris, including both SRBs.

Immediately after the 51-L explosion, ESMC took decisive action in determining debris fallout areas and impact times, as well as organizing search, salvage and rescue forces. A review of contingency planning documentation indicated that current contingency plans are based on non-catastrophic occurrences and were not adequate for support of the STS 51-L failure. The response to the 51-L explosion by the range instrumentation and command personnel was excellent, demonstrating extensive experience and knowledge.


B. Flight Readiness Review Process.

The Flight Readiness Review Team undertook a critical review and analysis of the launch readiness on STS 51-L. The purpose of the review and analysis was to ascertain the adequacy of the process and to determine if the Flight Readiness Review Process was effective in providing the launch decision for 51-L. The methodology utilized was a thorough analysis of policy, procedure, and plans associated with the Flight Readiness Certification process, followed by analysis of the 51-L Flight Certification documentation.

The Shuttle Flight Readiness Review process is a carefully structured management activity designed to certify readiness of the Shuttle vehicle for flight. It is an incremental process covering all aspects of readiness (manufacture, assembly, test, checkout, mission operations, safety, reliability, and launch and landing operations). The predominant management reviews focus toward the FRR, approximately two weeks prior to launch. The FRR, as identified in NASA Program Directive SPO-PD 710.5A, is a consolidated review of all activities/elements necessary for safe and successful conduct of the launch, flight, and post-landing operations. The review is chaired by the Associate Administrator for Space Flight, supported by the NASA Chief Engineer, the Center Directors, project management from JSC, MSFC, and KSC, and senior representation from the STS contractors. There are significant readiness review activities conducted at the Levels II and III program levels prior to the Level I FRR. The reviews at JSC, MSFC, and KSC include detailed assessment from all program elements at their respective centers. In support of the NASA Flight Readiness Reviews, responsible contractors conduct, as required by contract, internal Flight Readiness Reviews. Each contractor formally certifies, through the internal process and through participation and signature at the Level III reviews of the flight readiness, the elements/systems for which he is responsible. The final structured FRR activity is the L-1 Day meeting, a final readiness status that includes closeout of actions from previous meetings. The L-1 documentation includes readiness signoff by NASA and contractor management. The Shuttle Certification of Flight Readiness (CoFR) is an endorsement by Space ,Shuttle program elements that satisfactory completion of the manufacture, assembly, test and checkout has been accomplished. The CoFR process is managed by JSC Level II and implemented by all elements of the NSTS program.

The responsibility of each of the element projects, including contractor elements, is to certify adequacy of hardware design, fulfillment of design and performance requirements, configuration, availability and disposition of required documentation, and readiness of the element(s)/systems from the manufacturing phase through integration and checkout at the launch site. National STS Program Directive 107G establishes a Mission Management Team (MMT) for Space Shuttle missions and assigns responsibilities for insuring timely statusing of launch countdown/flight activities and resolution of issues extraordinary to the established guidelines and constraints for the Launch Director and the Flight Director. The MMT is functional for each Space Shuttle, beginning 48 hours prior to launch and continuing through post-landing crew egress and Orbiter safing. The Mission Management Team functions on an on-call basis during this entire period. The MMT provides the STS Program Manager with the technical advisory structure needed to develop recommendations on STS anomalies and required changes to previously agreed to launch rules, flight rules, flight plans and systems limits or redlines. The STS 51-L Flight Readiness Review Process was implemented consistent with NSTS Flight Certification policies, procedures and practices. The technical management from each level of the program was typical in both timing and depth of detail to that used in previous mission processes. However, events associated with the STS 51-L mishap identified SRM flight safety issues not [I12] addressed in the FRR process (see Section VIII. Findings and Conclusions).


C. Pre-Launch Security.

The Pre-Launch Security Sub-Team has conducted a thorough review of the security programs and procedures in effect at the Kennedy Space Center, relevant to the STS mission processing flow and launch. These programs include the disciplines of personnel. industrial, communications, physical, technical and operational security and counterintelligence support. These responsibilities are carried out by the Kennedy Space Center Security Office Staff utilizing contractual services from a variety of contractors at the Center. The Base Operations Contractor (BOC) provides a guard force responsible for protecting sensitive operational areas (e.g., OPF, VAB, Pads A and B), and for the maintenance of a command post for security operations during launch. major events and emergencies. Additionally, the BOC provides security support in areas such as intrusion and alarm systems, general investigations, security surveys of NASA facilities, security support to off-site contingency operations, badge and area permit issuance, security education, and classified document control.

Immediately after the loss of Challenger on January 28, 1986, the KSC Security Office, BOC, SPC, and many other KSC organizations initiated actions relating to the accident in the following areas:


1. Clearing and Closing of Safety/Security Areas.

a. A safety area around LC-39 Pad B was cleared of all personnel prior to launch. This operation, referred to as the Impact Limit Line Clear (ILL), is accomplished for both safety and security reasons. Subsequent to the clearing of ILL, access to the area is controlled through a man-loading system. Individuals with a previously validated need to enter the ILL are identified by name and authorized access on a case-by-case basis. The ILL is normally released in segments within minutes after launch. Subsequent to the STS 51-L mishap, the decision was made to hold the ILL.

b. Immediately after the accident, the BOC was directed to re-establish KSC outer gates and allow entry only to properly badged personnel. Spaceport USA was advised that no bus tours would be conducted and that they should be prepared to close for the day. Visitors to the Center were permitted to egress the Center in the normal manner. Families and friends of the STS 51-L crew were relocated to a safe and stable area with special attention given to their medical and other needs.


2. Impoundment of Records.

a. Within minutes after the STS 51-L mishap, an announcement was made from the Firing Room in the Launch Control Center (LCC) that all data and records relating to the STS 51-L mission were to be impounded and safeguarded.

b. The KSC Security Office contacted the NASA Test Directors (NTD) in the LCC and established ground rules for security support. Security supported the impoundment process through the use of guards, special keying systems, security containers and other special security procedures.


3. Security Search.

a. In the days immediately following the STS 51-L accident, the BOC. under the direction of the KSC Security Office, initiated a series of area searches. The purpose of the area searches was to locate and identify STS 51-L debris, and from a security perspective, to identify any unusual or out of place items that would be of security interest.

b. BOC formed a special team to conduct searches and developed a methodology to insure searches were conducted in a thorough and efficient manner. A map of the area to be searched was divided into grids and the search was conducted in a manner that insured all areas were examined by at least two search teams. Items identified as possible debris were photographed as they were found, location noted on a map, and detailed on an evidence form. BOC utilized standard evidence procedures to convey the items to the appropriate collection point. Thirty-three items were identified, photographed, logged, and delivered to the debris collection point.

c. During the period February 5-6, 1986, BOC conducted a security walkdown of LC-39 Pad B to include the FSS/RSS, the Pad apron/slope, the high-pressure gas tunnel, the flame trench, the mobile launch platform and the ground area extending to the pad fence. Thirty-nine items were identified, photographed, logged, and delivered to the debris collection point.

d. During the period January 29 through March 2, daily vehicular and foot patrols were conducted of beach areas under BOC cognizance. Debris items were collected and delivered to the appropriate debris collection point.


4. Investigative Activities and Liaison.

a. On January 28, 1986, within hours of the Mission 51-L mishap, on-site and/or telephonic contact was made with offices of the FBI, USAF (OSI), USSS, NASA Headquarters Security Office, intelligence-counterintelligence agencies, and local law enforcement agencies for the purpose of coordinating the collection or analysis or any information, investigative leads, debris or offers of video tape or photographic records of the accident.

b. Video tapes and photographs acquired by the KSC Security Office were forwarded to the Data Design and Analysis Task Force's (DDATF) Photo Analysis Team. Letters received by or brought to the attention of the KSC Security Office were evaluated as to content and either acted upon or passed to the appropriate organization, such as the DDATF, or in the case of threats or allegations, to the FBI, USSS, USAF (OSI), or NASA Office of Inspector General. Of the nearly 4,000 letters reviewed, approximately 100 were categorized as "significant," based either ,on relevancy or other characteristics. By agreement, all STS 5 1-L related information or allegations that came to the attention of any FBI office was passed to the local FBI office, which, in turn, Coordinated action or disposition with the KSC Security Office.

c. A full and open exchange of information and investigative findings existed between the FBI and the KSC Security Office. Categories of information not normally available to the KSC Security Office were readily and freely provided. This enabled the KSC Security Office to examine a wide range of data, often accompanied by a knowledge of the credibility and reliability of the informant, and to evaluate it for trends or patterns.

d. On January 30, 1986, Security Office personnel viewed the STS 51-L launch films and observed the puff of black smoke between the starboard SRB and the ET. Security Office personnel initiated a preliminary inquiry to determine the probability that it high powered rifle could have been used to damage the SRB.

e. The BOC was directed to review all incident reports relating to the STS 51-L flow to determine if any were relevant to the STS 51--L mishap. No significant information relevant to the mishap was revealed.


The Pre-Launch Security Sub-Team's assessment determined that the security procedures and operations supporting the 51-L mission were adequate. Furthermore, the inquiry following the 51-L accident has not revealed any information indicating that any individual deliberately performed any malevolent act which contributed to the 51-L mishap. Also, as a part of the Pre-Launch Security Sub-Team's review, a series of recommendations were developed to enhance the security measures in providing protection (National Resource Protection) to the elements of the STS. The existing security systems are predominantly dependent on manpower. However, manpower efficiencies, strategies, and training cannot defend against certain threats, particularly given the vast terrain, ocean proximity and airborne concerns. There are additional items, including weapons, helicopter/aerial response capability, remote area sensors (water and land), vehicle barriers, berms of earth, training (for employees and security personnel) [I13] and training facilities, which could be included. Manpower intensive programs do not defend or protect against all threats postulated at KSC. The current operator managed facilities, having a minimal work/integrity control program, do not provide the necessary complement to the available security measures and hence implementation of NRP upgrades needs assessment (see Section VIII, Findings and Conclusions).


VIII. Findings and Conclusions.

This section provides a listing of those findings resulting from the review conducted by the Pre-Launch Activities Team that were adjudged to be significant in that they were deemed to warrant attention by the Presidential Commission or follow on action by NASA management. These findings resulted either from very specific events/situations encountered during the 51-L mission preparation that should be avoided or corrected or from more general, observations of existing operational practices where improvements can and should be implemented.

Each finding is accompanied with a discussion that summarizes the concerns that were manifested during the review and in many cases offers recommendations for corrective action.



No factors contributing to the 51-L accident were found in the STS processing review.



The reports contained in Section VII of this document represent a detailed analysis by each of the study/review teams. Collectively, they cover the full range of launch systems and processing analyses.

Typically, the teams approached their reviews and arrived at their findings by identifying all critical documentation, processes, and activities within their areas of responsibility. They performed a detailed analysis of each item. Collectively, these became a thorough analysis across the total processing operation. Particular emphasis was placed on the review of unplanned events and/or problems, and the documentation (IPR's, PR's, deviations, waivers, etc.) associated with these events. The reviews covered overall preparations, buildup, and integration of the facilities. GSE, and flight hardware involved in Mission 51-L. They included in-depth engineering, operations, quality and safety, assessments of processing and work authorization documentation.

It is significant to note that throughout these detailed analyses/reviews the teams, neither individually nor collectively, were able to identify any anomaly/discrepancy in the STS processing flow (including vehicle and payloads processing, integration or operations) that contributed directly to the STS 51-L mission failure. However, even though the team reviews indicated no factors contributing to the STS 51-L accident the design of the SRB is such that there is no positive method to assure problems with the field joints are not present.

Many items where operations can be improved were identified. They will be recommended for implementation as a result of the reviews. These items are addressed in the individual team reports and the other findings in this section.



The right hand SRB aft field joint was properly assembled using established, approved procedures incorporating the design requirements, but the design is such that there is no positive method to assure that joint sealing degradation has occurred due to assembly damage to the O-ring, contamination being generated, or water being trapped in the joint.



The SRB joint Mate Review Team conducted a detailed review of the planning and requirements documents which controlled performance of the SRB right hand aft field joint assembly for STS 51-L. It was concluded that the procedures were properly, prepared, incorporated all requirements imposed by the design agency (NASA/MSFC) and were properly approved and released for use.

The Review Team examined the actual planning documents and authenticating documents used in performing the SRB right hand aft field joint mate operations on STS 51-L. The team also examined the actual planning and authenticating documents used to inspect the clevis and tang joints of the two segments during receiving inspection. It was concluded that the required operations and inspections were conducted in accordance with the approved, released documentation and that, except for minor discrepancies, all required technician, contractor quality inspector, and NASA quality inspector stamp authentications were present.

The Review team reviewed the background and experience of the technicians, inspectors and supervisors who were involved with the joint mate operation. It was determined that all personnel were experienced in the operations being performed, having participated in a number of previous SRB stacking operations. The least experienced technician had participated in five previous launch vehicle stacks (10 SRBs), while many had participated in 14 launch vehicle stacks (28 SRBs). There were no personnel who had never participated previously in joint mate operations. It was concluded that the joint mate operations were performed by well experienced personnel.

A sub-group of the Review Team interviewed a majority of the technicians and inspectors who participated in the STS 51-L right aft field joint mate. These interviews, while providing interesting supplemental commentary, did not bring to light any data or information not already identified by other team investigations. In general, the only factor which permitted any of the interviewees to remember this joint mate was the fact that the rounding too] was used. It was concluded from the interviews that the processing of the STS 51-L right aft field joint mate was routine. with no noteworthy abnormalities, variations. or unusual circumstances.

The Review Team reviewed all major process changes incorporated into the joint mate operations since STS-1. The most recent change, one involving zinc chromate putty lay-up patterns and thicknesses, was introduced on STS 61-A. SRBs incorporating that change have flown on STS 61-A, STS 61-B, and STS 61-C. Some O-ring anomalies were experienced on 61-A and 61-C. All other joint mate process changes were introduced earlier and have flown successfully several times. It was concluded that there were no process changes incorporated for the first time during STS 51-L joint mate operations.

The Review Team reviewed the joint mate processing history and determined that there were no processing variations which had not been experienced on previous SRB stacking operations. The segment stacking sequence used had been used on four previous launch vehicles since STS 41-C, the time required to complete joint mate and leak test was average when compared to SRB segment processing times for the previous five launch vehicles, and the Circumferential Alignment Tool had been used on five joints prior to STS 51-L. It was concluded that variations in sequence and technique used in STS 51-L joint mate operations were typical of previous program experience.

Testing has shown that even though the SRB joint has met the processing requirements, including a successful leak check. O-ring damage or contamination may exist that could contribute to subsequent joint failure. In addition, there is no design protection from rain water intrusion into the field joint and no method to test for the condition. The failure mechanism associated with these conditions is discussed in the Accident Analysis Team Report.



The Work Control Documentation System requires revision.


[I14] Discussion

The Work Control Documentation System, or "paper system" for processing, controlling, tracking, and providing traceability of flight and ground system elements and their associated hardware/software, needs review. The individual team reviews uncovered a number of Work Authorization Documents with some sort of problem. These included a lack of timely closure: poor annotation of deviation steps; lack of traceability: and missing signatures and quality control stamps.

While many documents had errors, generally the overall error content within a given document was small. For example, a single missed quality control stamp would indicate a problem document: however, a sample of over 20,000 steps requiring quality control stamps showed approximately º of 1 percent were missing. This rate does not indicate a major problem. but there is a need to understand why any stamps at all are missing.

The present Work Control Documentation System has evolved throughout the manned space program to reach its present form. The system's purpose is to assure that all work to be performed is properly defined and authorized; that adequate steps are taken to oversee the work and assure it is done properly and that the work activities can be reconstructed in the future if desired. It is important that the system operate correctly, since it is the key to vehicle configuration control and proper operations. For example, during the STS-9 destack operation, water was found to be present in the SRB joints; a fact known throughout the program at the time, but not documented. This could have provided information that would have been most helpful in the STS 31-L reconstruction.

Since the system covers all facets of vehicle work. it contains many different document types (or paper) which are processed differently. depending on the particular document function. Interim Problem Reports (IPR's) are written to define and authorize the work needed to isolate the cause of a problem found during testing. Additionally, the IPR may result in a Problem Report (PR), if the problem is caused by a failed part. The PR is used to authorize the failed part's replacement and retest. Since these activities may occur over some period of time, such as five or six days, the tracking of the work and open "paper" becomes complex. It is essential that the documentation be complete throughout the total process since the ability to reconstruct the activities in the future rests upon the written records.

In some cases where the documentation was incomplete the reconstruction activity was time-consuming, and might have been impossible if more time had elapsed since the ground processing of STS 51-L. The prime conclusion reached was that the system needed to be reviewed and revised, to make it fulfill its fundamental requirements in a fashion that would encourage compliance by the users; i.e., make the system "user friendly." Secondly, employee training in how to use the revised system should be instituted, with an emphasis upon the importance of the system and the need for thorough and complete documentation.

A review of the Work Control Documentation System has been initiated. The review is following up the team review findings. It is anticipated that will lead to a system revision which will improve operating performance.



Manpower limitations due to high workload created scheduling difficulties and contributed to operational problems.



During the team reviews instances were noted where manpower limitations had caused operational difficulties. These generally caused delays in supporting ongoing STS 51-L operations. However. in some instances it appears that manpower limitations may have been a contributor to problems cited in other findings, such as in the Work Control Documentation System. The delays contribute to inefficiencies and consequently are not operationally desirable.

The fundamental reasons for the manpower limitations stem from a high workload, and some areas where particular skills are in short supply. The high workload during the STS 51-L ground processing was created by the processing of four Orbiters while also completing the Launch Complex 39B activation. Problems in processing the Orbiters were further increased by a substantial reliance upon part "cannibalization" to support the operations. This was compounded by the STS 61-C activity, which moved from a planned December 18, 1985 launch date to January 12, 1986. This unplanned delay. along with the intermediate launch attempts, created a higher than anticipated demand upon manpower. resulting in schedule limitations. In some skills, such as test conductors and senior engineers, the higher than normal test activities created abnormal demands upon their availability.

The manpower limitations were recognized, and were considered to be a relatively short-term problem. The buildup in activity had started during the summer of 1985, with four Orbiters starting into test and the systems test activities associated with LC-39B activation. These activities peaked in November 1985 (overtime reached 15 percent) and were forecasted to be reduced substantially by March 1986. At this time there would be only three Orbiters in processing at KSC, and the LC-39B activation would be complete. Even though the May 1986 planetary missions represented a major technical challenge, the overall workload, associated with processing three Orbiters was expected to decrease. Therefore, a substantial manpower buildup to meet the relatively short-term increase was not believed to be warranted.

Planning is currently underway with a view to operating in a manner that will minimize manpower impacts. Different techniques are being evaluated to decrease the impact upon critical skills. as well as methods to develop additional personnel in these areas.



Launch Complex 39B requires additional modification.



Launch Complex 39B demonstrated satisfactory capability during the STS 51-L launch, with a few exceptions. Since STS 51-L was the initial Shuttle launch from Launch Complex 39B, it was anticipated that additional modifications would be identified during its first use. Such modifications normally involve changes to make the facilities less susceptible to launch damage, as well as to correct minor operating problems.

In addition, a revised freeze plan was first used during STS 51-L, which allowed vehicle operations to safely continue at below freezing temperatures. The freeze plan was successful in that vehicle operations continued but the resulting buildup in ice is not considered desirable for future operations. Future planning must determine if it is essential to be able to operate at below freezing temperatures. If so, water system modifications will be required.


The modifications indicated above are further elaborated in the following:


1. Pad Water Systems.

Environmental conditions, combined with a breakdown in the freeze protection plan, resulted in large quantities of ice forming on the Fixed Service Structure (FSS) during the night prior to the launch of mission STS 51-L. The "Freeze Plan" required that certain Firex and potable water systems be left flowing slightly, into open drains, so that freezing conditions would not result in pipe ruptures. As this water flowed, high wind conditions blew the water away from the drains, causing ice to form on decks, structural members, handrails, cable trays, and floor gratings. The wind experienced during the early morning hours further aggravated the situation by spreading the flowing water over large [I15] areas. The ice that formed (as sheets and icicles) is a concern because of the potential as a debris hazard to the Orbiter Thermal Protection System. Also the ice accumulated on the walkways leading to the slidewire escape baskets which could have added to the danger of a hazardous pad contingency situation.

Changes should be made to the Freeze Plan to eliminate the necessity to leave water flowing as the method to prevent pipe ruptures. Modifications to the appropriate pad water supply systems and drain provision should be accomplished, and changes to the implementation of the procedures made so that excessive flowing water is not required. Action has been initiated to define the modifications required to resolve the pad water/ice formation problem. Since Pad B and Pad A are similar insofar as water systems, it follows that any modifications should be done on both Pads and all MLPs.


2. Additional Pad 'Hardening" Modifications.

The Pad B Facility Team and other systems personnel accomplished walkdowns of the pad, following the launch of mission STS 51-L, in which detailed descriptions of launch damage were recorded. The findings (reported in the Pad B Facility Team Report) amounted to 302 separate line items.

The total is larger than that recorded on previous launch damage assessments. However, some of these items would not have been reported were it not for the STS 51-L mishap. The inspection team was "sensitized," and so reported items which were considered "good" or normal during previous launches. Others were items directly attributable to the freeze/water problem, and items of the general category of unfinished (although functional) installations. A review of the detailed list shows 11 "good" reports, 18 "freeze/water" items, and 57 "unfinished" items; leaving 216 items directly attributable to the launch/blast damage.

These items, such as panel covers blown loose, cable tray covers blown off, doors blown off, OIS boxes blown open, threaded junction box cover blown off, etc., are considerations for hardening modifications. In many instances, a simple "blow-out" plug would provide protection from negative pressure blast effect and prevent damage (except to the plug itself). In other instances simple locking devices would serve to secure vibration sensitive equipment. Other covers may actually require "beefing-up" to preclude damage; e.g., the SRB holddown post cover. Such hardening would further decrease the potential for loose debris during liftoff, and would enhance pad turnaround times. A study of appropriate hardening has been initiated. Again, any action taken should be applicable to both Pad A and Pad B, and all MLPs.


3. Pad A and Pad B System Differences.

While minor, there exists differences between Pad A and Pad B systems which contributed to some processing problems during the STS 51-L flow. For example, a GSE patching error resulted in an IUS to Orbiter R.F. link Problem Report. A contributing factor was the dissimilarity of the Pads A and B patch panels. Differences in the location of payload GSE between Pads A and B required the processing of several waivers for GSE placement. There also exists some confusion relative to the phasing of power on some Pad B circuits. This required payload GSE that had previously been used on Pad A to be rewired for use on Pad B. In this light, Pads A and B systems are being reviewed to determine if modifications are warranted.



Test Team errors were found that were caused by not following established procedures.



During the STS 51-L processing reviews, a few cases were found where established procedures were not followed. Standard Practice Instructions require that certain "ground rules" be followed, to assure integrity and traceability in the Work Control Documentation System. Test team errors solely related to the Work Control Documentation System were previously addressed, and represent the majority found. The more serious error is one where problems go undetected and the potential consequences cannot be fully assessed. The most significant error encountered was during the launch countdown. While preparing for propellant loading, the LH2 Orbiter to ET Disconnect Valve was opened by the console operator. He had erroneously failed to follow the required steps in the OML. A follow-on error was made in that this occurrence was not properly documented. Since proper documentation was not present, a full assessment of the problem was not made prior to the launch of STS 51-L. Flight data from STS 51-L indicated the valve did perform satisfactorily.

Another major error occurred when the integrity seals on the ET aft restraints were broken and not reported. It is believed that the seals were broken in error, but the break of integrity was not reported in accordance with established procedures.

The underlying factors contributing to these errors were not determined during the processing reviews. However, indications are that a lack of appreciation for the serious results which can result from such errors is a leading contributor to the problem. A program needs to be instituted to reinforce the need to assure that problems encountered during the processing of flight hardware are reported. In addition, where critical hardware is involved, methods with the potential to reduce incidents of human error should be investigated.



The Test Requirements System needs revision.



The Test Requirements System needs revision to assure that required testing is accomplished during flight hardware ground processing.

Flight Vehicle test requirements are documented in the Operations and Maintenance Requirements Specifications Documents (OMRSD). Requirements effectivities are unique, and are either standard (every flight requirement), non-standard (at intervals of every 5th, 8th flow, etc.) or contingency requirements, such as upon component replacement. To track OMRS compliance, a computer data, base was developed that identifies which OMRS requirements must be accomplished on a particular flow, versus which Work Authorizing Documents (WAD's) satisfy those requirements. This document is the Operations and Maintenance Plan (OMP). To produce an OMP for a particular flow, the OMRS data base is sorted for only those requirements with the correct effectivities for flight elements/flight number, as defined in the Flight Element Assignment Table (FEAT) (i.e., STS-33, Orbiter OV-099 10th flight, ET Tank 26, SRB1 26, SRB2 26).

Findings of the review teams indicate that the OMP and the verification that all OMRSD requirements are satisfied is not a "closed loop" system. The verification rests solely on the systems engineer. The OMP is used only as a planning document. Presently, no method exists which verifies that the work identified in the OMP was accomplished. Once the OMRSD tracking system (OMP) is made to be a closed loop system, and the vehicle components with OMRS requirements are entered in the master file, the existing problems associated with the OMP will be eliminated.

While no problems were found that contributed to the STS 51-L mishap, the need to revise the Test Requirements System is evident. Work has been initiated to correct the problems found during the team reviews.



The Orbiter logistics system supporting 51-L was inadequate, causing significant LRU "cannibalization."


[I16] Discussion

The logistics support for Challenger in the STS 51-L ground processing was inadequate, since it created a need to remove parts from other Orbiters to continue STS 51-L operations (commonly referred to as "cannibalization"). For STS 51-L, 45 out of approximately 300 required parts were "cannibalized." These parts ranged from bolts to an OMS TVC actuator and a fuel cell. The significance to operations of "cannibalization" is that it creates (1) significantly increased efforts to accomplish the same work due to multiple installation and retest requirements, (2) schedule disruption due to added work and normally later part availability, and (3) Orbiter damage potential due to increased physical activity in the vehicles. These efforts make "cannibalization" an operationally unacceptable practice.

The Orbiter logistics problem has been created primarily by a delay in the initial spare parts inventory buildup, and out-of service parts. The initial inventory buildup for 12 flights per year was originally forecasted to be approximately 95 percent complete by the third quarter of FY86. At this time the inventory "lay in" is approximately 65 percent complete. Out-of-service parts stem from technical problems found with the existing parts. While these technical problems are being resolved, the remaining acceptable parts are moved from Orbiter to Orbiter until adequate replacements become available. This situation is created by the time required to fix the technical problem.

"Cannibalization" increases work effort significantly. Parts installed in Challenger came primarily from Discovery. This created :he effort to remove and replace an operable part from Discovery an order to satisfy a logistics demand for Challenger. Retests were required on both vehicles, rather than just on Challenger.

Since the removal and replacement of parts on Discovery was not a planned activity, a special procedure defining the work and retest requirements had to be generated. It had to reflect the specific time in the Discovery ground processing when the "cannibalization" activity would occur. This work is generally not planned, since approximately 80 percent of part failures occur during ground test and, therefore, cannot be forecasted. The disruptive effect upon the schedule compounds the increased work involved in the "cannibalization" by creating inefficiencies in the ground processing of both vehicles. Discovery's flow had to be disrupted for parts removal. Usually this meant the Challenger flow was disturbed as well, because of the extra delay experienced while waiting for the "new" part to arrive.

When additional physical work is performed on an Orbiter, potential for damage is always a threat. The exposure of electrical connectors, wiring, plumbing, and other items in the vicinity of the removed part provides a potential for damage. While careful inspections are made afterward to detect any such damage, and retests are undertaken to assure the systems function properly, the danger of latent damage is always a potential problem.

Because "cannibalization" causes such adverse effects, a concerted effort must be made to increase the Orbiter logistics system supportability levels. Efforts are underway to evaluate what methods can be taken to assure that "cannibalization" is a relatively rare occurrence in future STS operations.



Additional analysis will be required to assess the environmental effects upon launch capability.



The STS 51-L launch and subsequent examination has indicated that additional analyses need to be conducted to assure a full understanding of environmental effects upon launch capability. Following the STS 51-L launch, an examination of Launch Complex 39B indicated some systems had not operated properly in the below-freezing temperatures. In addition, the effects of the cold operating temperatures upon the SRB joints does not appear to have been fully understood. The difficulty in defining the operating environment adequately with the existing instrumentation and analytical models was not fully appreciated. Without a full assessment of the capability of both vehicle and facility to withstand adverse environmental conditions, the potential for unexpected problems will exist.



Ice debris was greater than predicted.



Ice debris created by the STS 51-L launch was greater than predicted by pre-launch analysis. The trajectories of wind-driven ice falling from the FSS/RSS were predicted, using aerodynamic analysis methods. These methods accounted for drag retarding the fall, and wind velocity imparting a lateral velocity component. The effects of plume aspiration and particle rebound off the MLP were not included in the analysis. At SSME ignition the wind direction was approximately 306 degrees, with a velocity of 10 knots. Based on this condition, the translation towards the Orbiter by particles from high levels should have been about 16 feet at the MLP level.

Launch films show that the vehicle rising off the launch pad caused considerable aspiration. This effect drew ice toward the SRB plume, with some ice striking the left hand SRB. However. no debris was observed to be moving toward the External Tank and Challenger. The actual FSS/RSS ice movement, as observed on the photographic documentation, did not conform to the predictions in two important respects:

1. The ice generally did not release until after SSME ignition.

2. The ice translated further toward the vehicle than predicted.

The late ice release compensated for the added translation, but the Orbiter moved out of the way before it could be hit. Future meaningful predictions of ice movement require that the effects of aspiration be considered. Also the release time of the ice must be known.



The 51-L Flight Readiness Review (FRR) Process, including the Mission Management Team (MMT) activities immediately prior to launch, was conducted consistent with NSTS flight certification policies, procedures, and practices.



The above finding resulted from a thorough analysis of pertinent NSTS FRR program documentation, including all available 51-L flight certification data.

The NSTS FRR decision-making architecture was judged to be structured to allow effective management of technical matters for NSTS flight readiness. The NSTS FRR process, as documented in program directives, is a derivative of NASA's manned spaceflight history. It is an intricate technical management process (people, communication, and documentation) to assure that identified flight performance and flight safety issues are adequately assessed.



The STS 51-L Flight Readiness Review process did not address critical SRB flight safety issues.



The chain of events which culminated in the STS 51-L accident indicates that the management process applied to critical flight safety issues was inadequate. The basic engineering understanding of the SRB field joint, and the effects of operating at low temperatures was lacking. Prior qualification testing and analyses were not adequate to support SRB use in the temperature ranges forecasted for the STS 51-L launch.

[I17] The Flight Readiness Review (FRR) process which leads to the launch decision is part of a total management system comprised of many reviews, beginning early in the development program. The engineering knowledge base continues to gross throughout the program, and is used as the basis for management decisions regarding flight readiness. The FRR primarily addresses changes to that baseline. Significant changes to the baseline such as new qualification data. a redesign of' the particular system, or the results from flight anomalies previously addressed are reviewed. However, if the original engineering baseline is lacking, the FRR "delta" approach may not cause the problem to surface.

Another problem with the FRR "delta" approach is that repeated anomalies tend to lose significance during subsequent reportings. During the SRB FRR presentations the relative importance associated with O-ring distress diminished. In fact, the STS 61-C O-ring erosion was not reported during the launch decision process.

In order to focus upon items essential for flight safety, a Critical Items List is compiled which identifies items whose failure could result in a vehicle loss. This focus is expected to detect areas requiring added attention in order to reduce flight safety risk to an acceptable level. The inadequate emphasis upon the safety critical items desensitized the program personnel to the need to focus upon safety.

The management tools described above did not adequately protect against the STS 51-L mishap. The launch decision followed established management directives, but the engineering knowledge base supporting the STS 51-L launch decision was inadequate.



Communication during the launch decision process was inadequate.



During the hours preceding the STS 51-L launch, there were a series of meetings regarding the vehicle's ability to successfully operate under the environmental conditions expected at launch time. In the discussion concerning the SRB joints and the Launch Complex ice conditions, key individual's objections to launch were not registered to the top program officials.

During the discussions concerning the SRB readiness for launch. Morton Thiokol engineers stated that they did not have a basis upon which to recommend launching. Further, they believed that their current activities with the SRB joint studies indicated a concern for cold weather launches. This concern did not reach the NSTS Program Manager and the Associate Administrator for Space Flight both of whom were in the Launch

Complex 39 Control Center. Both officials stated that this information might have influenced their decision to proceed with the launch of STS 51-L.

During the discussions in the LC-39 Launch Control Center concerning the ice conditions on Launch Complex 39B, Rockwell International officials participated. They expressed a concern for vehicle safety to the NSTS Program Manager. However, NASA participants in the meeting believed that the Rockwell International concerns were properly considered, and the ice risk was related to post-launch refurbishment, and was not a flight safety issue. The senior Rockwell International official, who was at Downey, California during the pre-launch discussions, subsequently stated that he still had a significant concern for STS 51-L flight safety. This was based upon potential launch complex ice debris, and he believed NASA officials had overruled his concerns. Later, NASA officials stated that they did not know the depths of the Rockwell International concerns, nor that they related to flight safety.

In both instances the communication was inadequate. and represents an area where the launch decision process requires reassessment. This activity is currently underway by NASA.



No factors contributing to the 51-L mishap were found by the security assessment.



The Pre-Launch Security Sub-Team Review provided an assessment of' the security procedures utilized at the Kennedy Space Center in support of the 31-L mission.

This review has determined that the security procedures and operations supporting the 51-L mission were adequate and no information has been developed to indicate any deliberate malicious act contributed to the mission failure.



Methods to improve National Resource Protection (NRP) should be reviewed.



While available information indicates that the 51-L accident was not caused by malevolent overt acts. the security measures proposed under the auspices of NRP would be able to provide a more prompt. effective and conclusive evaluation. The security systems described in the Pre-Launch Security Sub-Team report are predominantly dependent on manpower. Manpower intensive programs do not defend or protect against all threats postulated at KSC. It is recommended that the planning for implementation of NRP upgrades be reviewed.

Appendix H | Volume 2 Index | Appendix J