Fletcher, the Solid Rocket Motor Source Evaluation Board (SEB)

¶evaluated the proposals generated by the Solid Rocket Motor RFP. Thiokol scored 124 out of a possible 200 points for its motor design, the lowest score among the four competitors. The only design strength identified by the Board: "Case joint leakcheck capability increases reliability and improves checkout operations." lC

¶NASA, Marshall Space Flight Center, "Request for Proposal: Space Shuttle Program Solid Rock Motor Project," RFP 8-1-4-94-98401, Volume 1, July 16, 1973, pp. 1-3, 1-4.

Thiokol, ,"Executive Summary: Pro 1 for Solid Rocket Motor Project for the S ace Shut tle P r o y n , Publications No. 0 8 7 3 - 7 E - 1 , Volume 1, August 27, 1973, p. 3-10 ('fable 3-4).

¶NA A, Marshall S ace Shuttle Center, "Presentation to NASA Administrator: Solid Rocket Motor Project Source evaluation Board," RFP 8-1-4-94-98401, November 19, 1973, Chart D-4.

¶Nouember 1973.-The SEB Design, Development and Verification Team Report rejected proposals by Aerojet and United Technol- ogies Corporation to test motor performance at 40" and 90" Fahren- heit. The report stated that "The temperature conditioning of two motors to verify the motor performance over the range of 40" to 90" is not required, as this data can be obtained from the normal varia- tion in ambient conditions." Id

¶December 12, 1973.-NASA Administrator James C. Fletcher ar,- nounced selection of Morton Thiokol as contractor for Design, De- velopment, Test and Evaluation (DDT&E) of the Solid Rocket Motors. In the source selection statement, "Selection of Contractor for Space Shuttle Program, Solid Rocket Motors," a statement was included that indicates that Thiokol ranked fourth out of the four bidders in the design category (See Appendix V-A). NASA, howev- er, placed greater importance on cost reduction and Thiokol had an attractive cost proposal.

¶January 9, 1978.-Major problems with the joint design were identified when Mr. John Miller of NASA sent a memo to Mr. Eudy. In it Miller stated, "Calculations performed by MSFC [Mar- shall Space Flight Center personnel] and agreed to by Thiokol show that distortion of the clevis joint tang for any joint can be suffi- cient to cause O-ring/tang separation. Data from DMT-1 [Develop- ment Motor Test-1] showed that this condition could be created by joint movement . . ." Miller continued, "All situations which could create tang distortion are not known, nor is the magnitude of movement known." Miller also noted that 15 percent industry rec- ommended a compression value of 15 percent for adequate O-ring performance. He also cited a Thiokol test report dated August 15, 1977, TWR-11507, which showed a maximum compression of 5.8 to 7.0 percent for O-ring material and spliced joints. Finally, Miller also recommended a redesign of clevis joints on all on-coming hard- ware at the earliest possible effectivity to preclude unacceptable, high risk, O-ring compression values.

¶November 7, 1978.-Ten months later it would appear that there was nothing to worry about when a letter from E. G. Dorsey of Thiokol to Mr. George Hardy of MSFC contained the statement, "The extrusion data presented in the review and mentioned in the minutes have confirmed the capability of the O-rings to prevent leakage under the worst hardware conditions." Mr. Dorsey at- tached the Thiokol TWR-12019, dated October 6, 1978 to his letter.

¶February 2, 1979.-Mr. Eudy and Mr. Ray of NASA visited the Parker Seal Company. A trip report was sent to Messrs. Hardy/ Rice/McCool of NASA which contained the following statement "Parker experts would make no official statements concerning reli- ability and potential risk factors associated with the present design however, their first thought was that the O-ring was being asked to perform beyond its intended design and that a different type of seal should he considered. The need for additional testing of the present design was also discussed and it was agreed that tests which more ld NASA, Marshall Space Flight Center, "Design, Development and Verification Team Report. Solid Rocket M o t o ~

¶Project," November 1973, p. 50.²² Rogers Commission Report, Volume I, p. 199. o bid., Chart SRB-4. 2 1 Larry Mulloy, NASA, Marshall Space Fli ht Center, "STS-51L Level I1 Flight Readiness Review,'' January 14,1986. See Appendix VIII-g. 2 2 Discussion with Allan McDonald, September 4, 1986. Z3 Rogers Commission Report, Volume 11. See Chart 15 (p. H-10) and Chart 19 (p. H-12). s Ibid., Chart 30 (p. H-18). NASA, "Selectlon of Contractor for Space Shuttle Program, Solid Rocket Motors," January 2, 1974.

¶closely simulated actual conditions should be done." This report also referred to the O-ring extrusion gap being larger than Parker had previously experienced. (See Appendix V-I.)

¶November 12, 1981.-During STS-2, the second Shuttle flight, erosion of the primary O-ring was discovered in the 90 degree loca- tion of the aft field joint of the right hand Solid Rocket Motor. The 0.053 inch erosion was not discussed in the STS-3 Flight Readiness review^.^ This was the deepest O-ring erosion that would be discov- ered in any case field joint.

¶February 25, 1983.-Employees of Thiokol discussed joint "gap size" and "O-ring compression" at a briefing at the Marshall Space Flight Center (MSFCh4

¶March I? 1983.-Mr. Lawrence Mulloy, MSFC Solid Rocket Booster (SRB) Project Manager, informed NASA Level 1 (meaning the Associate Administrator for Space Flight), of the pending change in criticality from 1R to 1, which meant that a single seal failure could result in the loss of the Shuttle and crew. That change was approved on March 28, 1983.5

¶April 4, 1983.-STS-6 was the first flight to use the "lightweight case." It was also the first flight where a criticality factor of 1, in- stead of lR, was assigned to the joint. After the flight, "blowholes" in the nozzle to case joints, not the case field joints, were found in both the left and right Solid Rocket Motors. These observations were not discussed in the Flight Readiness Reviews for STS-7.'j

¶December S, 1983.-An internal Marshall Space Flight Center (MSFC) memo from Mr. Miller to Mr. Horton highlighted the seal leak detection and zinc chromate putty problems. (See Appendix V-D.)

¶February 22, 198.4.-Marshall Space Flight Center memorandum from Ben Powers to Horton requested that post-flight and post- static firing inspection on specific joints be made. The memo ex- pressed concern about adhesion life of the zinc chromate sealant after installation on the SRM. See Appendix V-F. March 2, 1984-Thiokol personnel described the erosion discov- ered in the 351 degree location of the left Solid Rocket Motor for- ward field joint of STS-41B at a Flight Readiness Review. The ero- sion extended over three inches with a maximum depth of 0.040 inches. This was the first time the subject of O-ring erosion sus- tained on flights STS-2 and STS-6 was discussed as a technical issue at a Flight Readiness Review.'

¶March 8, 1984.-The notion of ACCEPTABLE EROSION was mentioned at a meeting of the Shuttle Projects Office Board for STS-41-C. Even though the joint was now classified as Criticality 1, which meant that failure of the joint could lead to the loss of the Shuttle and crew, the concept of "maximum possible" erosion, 0.090 inches, was accepted as an absolute value based on a comput3 Thiokol Report, TWR-300209, Brian Russell, "Narrative History of SRM Seal Erosion and Blowby Incidents," June 25, 1986, p. 3.

¶er program which was supported by limited data. Furthermore, the 0.090 inch value was based on the concept that the O-ring would seal at 3 times the actual motor pressure even if the erosion ex- tended to 0.095 inches thereby giving comfort in continuing with a known problem,8

¶March 1984.-Thiokol submitted their "Performance Charateris- tics of the SRM O-ring Assembly Test Plan," TWR-14336, which contained the following statement: "O-ring seals in rocket motors in general and the Space Shuttle SRMs in particular can suffer thermal degradation because of exposure to the high temperature motor chamber gases. Although none of the SRM primary O-rings to date have failed to perform their design function, there is some concern because of isolated events which show localized erosion as high as 0.053 inches. The postulated scenario for this thermal deg- radation effect is a short time duration impingement of a high energy jet which is induced during ignition pressurization by a combination of voids in the protective vacuum putty and the filling of available free volumes created by the tolerances of mating parts and the O-ring slots."

¶March 20, 1984.-Acceptable erosion was again discussed at the Flight Readiness Review briefing to the Marshall Center Board.g

¶March 27; 1984.-Mr. Mulloy discussed O-ring erosion at the Level 1 Flight Readiness Review for STS41-C. As a result, he re- ceived an "action item" to review the case and nozzle seals. The action did not have to be completed before the flight of STS41-C.l0

¶Mr. Lawrence Wear, the Solid Rocket Motor (SRM) Element Manager, then directed Thiokol to establish a plan and a test pro- gram to investigate the issue. Thiokol was directed to determine if the O-ring erosion was acceptable and if so, why?'

¶April 6, 1984.-Heat degradation of the O-ring in the left SRM aft field joint of STS41-C was found, along with "blowholes" in the putty.

¶April 12, 1984.-In an internal Marshall Space Flight Center memorandum, John Q. Miller told Mr. Horton that "stacking diffi- culties and observed O-ring anomalies" were increasing with the use of Randolph putty. The former supplier, Fuller O'Brien, had discontinued producing the putty previously used in the Shuttle program. Accordingly, putty was ordered from Randolph Products. The memo requested expedited development of a putty with the characteristics of the Fuller O'Brien putty used prior to STS-8.

¶May 4, 19&.-Morton Thiokol prepared a Program Plan for the protection of Space Shuttle SRM primary motor seals. Thiokol's ob- jective was to isolate the joint problem and to eliminate damage to the motor seals, the O-rings. The plan called for analysis and test- ing of O-rings, putty and associated lubricants.12 See Appendix V-B. May 23, 1984.-NASA responds to Thiokol's plan, endorsing the Program Plan, supplementing it and expressing continued concerns about zinc chromate putty performance. See Appendix V-C. May 30, 1984.-A presentation by Thiokol personnel at the SRM Preboard Flight Readiness for STS41-D described the problems with STS41-C.14

¶June 8, 1984.-The Marshall Center Board review for STS41-D took place without mention of the SRM problems found on STS41-C, even though Thiokol had prepared briefing charts for the review. l5

¶June 18, 1984.-MSFC memorandum from Miller to Horton men- tioned zinc chromate putty installation discrepancies and recalled erodedlheat exposure O-ring experiences on QM-4, STS-2, STS-6, STS-ll(41B) and STS-13 (41C).

¶June 18, 1984.-The Level 1 Flight Readiness Review for STS41-D took place, but again without mention of the O-ring prob- lems discovered on STS41-C. June 29, 1984.-Scenario of hot gas jet impingement against 0- ring is substantiated in a teleconference between Thiokol and MSFC.

¶August 30, 1984.-STS41-D was launched. Upon disassembly of the SRM casings at the Kennedy Space Center (KSC). O-ring ero- sion was found in both the right-hand forward field joint and the left-hand nozzle joint. The field joint erosion was 0.028 inches deep and extended over a 3 inch span in the 275 degree location.16

¶September 12, 1984.-Thiokol personnel discussed the problems with STS41-D at the STS41-G SRM Preboard Review."

¶September 19, 1984.-For the first time, at the STS41-G Shuttle Projects Board review, Mr. Mulloy mentioned the term "allowable erosion." He used the same briefing charts on September 20 at the Marshall Center Board Review.'*

¶Flights STS41-G and STS51-A successfullv flew without O-ring damage, a fact that was mentioned in th;! SRM Preboards four STS51-A and STS51-C. l9

¶January 24, 1985.-With a calculated O-ring temperature of 53 degrees F, STS51-C suffered erosion and blow-by in the two case field joints. The primary O-ring in the left-hand forward field joint was eroded 0.010 inches over a span of 4.25 inches at the 163 degree location, with a considerable amount of soot between the primary and secondary O-rings. The primary O-ring in the right- hand center field joint was eroded 0.038 inches over a 12.5 inch space at the 354 degree location. There was soot behind the pri- mary O-ring over a 110 degree arc and the secondary O-ring was heat damaged over a span of 29.5 inches.

¶January 3 1, 1985.-At the STS51-E Preboard review, Thiokol personnel described the previous O-ring damage in detail as well as l 3 NASA, letter from John Miller, MSFC. "Evaluation of TWR-14359, 'Program Plan, Protec. tion of Space, Shuttle SRM Prima Motor Seals,'" EP 25 (84-49). M a y 23, 1984.

¶"-ern Commission %port, V X m e XI, p. H-1.

¶I5Ibid.

¶I6Ibid.

¶I'Ibid., p. H-2.

¶'OIbid.

¶IsIbid.

¶joint performance. They also showed analytical predictions of the I< maximum expected erosion." 2o

¶February 12, 1985.-Mr. Mulloy and Thiokol personnel presented a summary of STS 51-C O-ring related problems during a briefing to the Shuttle Projects Office Board. A portion of the problem sum- mary on the briefing charts referred to a field joint O-ring blow-by problem as being an "acceptable risk." In this briefing the second- ary O-ring was referred to as a "redundant seal using actual hard- ware dimensions" even though the field joint had been officially classified as Criticality 1 for two years.21

¶February 14, 1985.-Mr. Mulloy addressed the Marshall Center Board but did not comment on the STS 51-C O-ring problems in detail.22

¶March Z 1985.-MSFC Memo to Mr. Mulloy from Mr. McCool. McCool was concerned that 14 months had elapsed since full scale diameter tests to provide data on zinc chromate putty behavior as it related to its effect on joint leak checks were requested. McCool pointed out that the only positive response from Thiokol was the Program Plan submitted on May 4, 1983.23(See Appendix V-E.)

¶April 4, 1985.-A letter from MSFC to Mr. Joseph Kilminster of Morton Thiokol requested specific sub-scale and full-scale tests on effects of zinc chromate putties on O-ring sealing integrity.

¶April 12, 1985.-STS 51-D was launched and, upon disassembly, erosion of the primary O-rings in both nozzle joints was discovered. The right-hand nozzle primary O-ring eroded to a depth of 0.068 inches over a 6 inch span at the 116 degree location. The left-hand nozzle primary O-ring eroded to a depth of 0.011 inches over a 2.12 inch span at the 14 degree location. There w as no blow-by past either nozzle O-ring.

¶April lc 1985.-The Shuttle Projects Board for STS 51-B was held without mention of seal problems. There was also no mention of seal problems associated with STS 51-C or 51-D at the Level 1 Flight Readiness Review on April 23, 1985.24

¶April 22, 1985.-Thiokol's evaluation of a second source for putty is issued. The evaluation states: "The Randolph Products putty is the only material presently qualified for use on the Space Shuttle Program. It is the desire of Morton Thiokol to evaluate and qualify a second source for a joint filler material." The evaluation went on to state, "The material has demonstrated poor processing charac- teristics and is moisture ~ e n s i t i v e . " ~ ~

¶April 24, 1985.-Problem Assessment System Record Number A07934, tracking damage to the field joint seals, contains the fol- lowing entry: "At NASA request, a solution for O-ring erosion will not involve a radical design change. Therefore, the possible solu- tions under current investigation are linked to: (1)new O-ring [maa a mid.

¶a s NASA, MSFC, Memo from Mr. Alex McCool, "Request for Initiation of Testing to Provide Data for Resolving the Burned O-Ring Seal Problem on the Space Shuttle SRM," EPOI (86-481, MtFh 7,1985.

¶Rogers Commission Report, Volume 11, p. H-2.

¶*5"hiokol, S.H. Cardall, "SRM Evaluation of Second Source Joint Filler Material," TWR- 14946, April 22, 1985, pp. 1-2.

¶terials] and/or diameter and (2) new vacuum putty and/or layup procedure.

¶April 29, 1985.-Flight STS 51-B was launched and when the Solid Rocket Boosters were recovered, it was found that the worst O-ring erosion to date had occurred. The left-hand nozzle primary O-ring eroded to a depth of 0.171 inches over a 1.50 inch space a t the 54 degree location. There was evidence of considerable blow-by. The secondary O-ring was eroded to a depth of 0.032 inches over a 3 inch span which was also at the 54 degree sector. The right-hand nozzle O-ring eroded to a depth of 0.005 inches over a 3.50 inch span at the 14 degree location.

¶May 8, 1985.-Blowholes through the putty in one field joint from each of the STS 51-B SRMs was mentioned before the SRB Board for Flights STS 51-F and STS-51-G. May 29, 1985.-The STS 51-G Shuttle Project Board took place without mentioning O-ring problems.2 6

¶May 13, 1985.-The Center Board Review for STS 51-G took place without mentioning O-ring problems.27

¶June 11, 1985.-The Level 1 Flight Readiness Review for STS 51- G took place without mentioning O-ring problems.28

¶June 17, 1985.-STS 51-G was launched, experiencing blow-by and erosion in both nozzle joints. The right-hand nozzle primary 0- ring was eroded in two different places. The left-hand nozzle pri- mary O-ring was also eroded and there was blow-by associated with all three locations.

¶July 1, 1985.-A combined Flight Readiness Review for the Mar- shall SRM Preboard, SRB Board, Shuttle Project Office Board, and Marshall Center Board was held at which Thiokol personnel pre- sented an extensive analyses of the problems discovered on Flight STS 51-B."

¶July 2, 1985.-Mr. Mulloy briefed the Level I Flight Readiness Review for STS 51-F and presented the STS 51-B O-ring erosion problem as a "closed item." Mr. Mulloy based this resolution on the use of a higher 200 psi leak check stabilization pressure and introduced, for the first time, a rationale for accepting secondary O-ring erosion. The Roger Commission would not find any refer- ence to O-ring problems in any Flight Readiness Review associated with Flight STS 51-D or STS

¶July 19, 1985.-An attempt to form an SRM Erosion team at Thiokol "virtually failed" according to Mr. Roger M. Boisjoly be- cause of lack of commitment on the part of Thiokol personnel.

¶July 22, 1985.-One of the engineers who appreciated the joint problem was Mr. Boisjoly of Morton Thiokol. In a "Progress Report" he wrote, "This problems has escalated so badly in the eyes of everyone, especially our customer, NASA, that NASA has gone to our competitors on a proprietary basis and solicited their experiences on their joint configuration."31 (See Appendix V-G.)²⁶²⁶ Ibid., p. H-42. Ibid. 2T Ibid.²² Rogers Commission Report, Volume I, p. 199. o bid., Chart SRB-4. 2 1 Larry Mulloy, NASA, Marshall Space Fli ht Center, "STS-51L Level I1 Flight Readiness Review,'' January 14,1986. See Appendix VIII-g. 2 2 Discussion with Allan McDonald, September 4, 1986. Z3 Rogers Commission Report, Volume 11. See Chart 15 (p. H-10) and Chart 19 (p. H-12). s Ibid., Chart 30 (p. H-18). 8 Ibid.²² Rogers Commission Report, Volume I, p. 199. o bid., Chart SRB-4. 2 1 Larry Mulloy, NASA, Marshall Space Fli ht Center, "STS-51L Level I1 Flight Readiness Review,'' January 14,1986. See Appendix VIII-g. 2 2 Discussion with Allan McDonald, September 4, 1986. Z3 Rogers Commission Report, Volume 11. See Chart 15 (p. H-10) and Chart 19 (p. H-12). s Ibid., Chart 30 (p. H-18). 9 Ibid.³⁰³⁰ bid. 3 7 bid., Chart 2 2. Rogers Commission Report, Volume V, p. 834. y r ' O b i s ammission &port, Volume 11, p. . H-P Kid., p. H-3.³¹³¹ Cmte Hgs., Transcript, June 17, 1986, p. 185. Thiokol, Roger Boisjoly, "Progress Report: Applied Mechanics Center," July 22, 1985.

¶6 4 - 4 2 0 0 - 86 - 3

¶July 29, 1985.-STS 51-F was launched without O-ring erosion problems. However, there was a blowhole through the putty in the right-hand SRM nozzle and the primary O-ring was affected by heat.

¶July 31, 1985.-Boisjoly wrote a n interoffice memo to R.K. Lund, Morton-Thiokol's Vice President of Engineering: On it, he warned that the rationale for flying the joint design was now suspect as a result of the secondary O-ring erosion on STS 51-B.318 See Appen- dix V-J.).

¶August 7, 1985.-The Shuttle project review for STS 51-1 was conducted, followed on August 13 by the Marshall Center Board and on August 15 by the Level 1 Flight Readiness Review. The 0- ring damage was noted at these reviews.

¶August 19, 1985.-Thiokol gave a presentation to Mr. Weeks, NASA Deputy Associate Administrator for Flight (Technical), and others at NASA Headquarters, which contained the following chart.