REG NASA-LLIS-0949-2001 Lessons Learned Solid Rocket Motor Case-to-Nozzle Joint Wiper O Ring and Vent Slot Addition.pdf

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1、Lessons Learned Entry: 0949Lesson Info:a71 Lesson Number: 0949a71 Lesson Date: 2001-03-27a71 Submitting Organization: MSFCa71 Submitted by: Billy Cole / RetiredSubject: Solid Rocket Motor Case-to-Nozzle Joint: Wiper “O“ Ring and Vent Slot Addition Description of Driving Event: The Challenger (Space

2、Shuttle Flight #51L) accident triggered a detailed review of all of the joints in the Solid Rocket Motor. Analyses showed a potential weakness and potential flow paths for hot gasses through he case-to-nozzle joint that could cause a catastrophic event similar to that encountered in Challenger.Lesso

3、n(s) Learned: A wiper “O“ ring and wiper vent slots are required in the glass phenolic layer of nozzle insulation to prevent entrapment of air in the case-to-nozzle joint during assembly, and to prevent polysulfide adhesive from contaminating the primary “O“ ring. The wiper “O“ ring, along with the

4、polysulfide adhesive, provides two thermal barriers before motor combustion gasses could reach the primary seal.Recommendation(s): Add an “O“ ring groove and “O“ ring to the nozzle interface between the nozzle glass phenolic insulation and the case insulation. A wiper vent slot and vent port are als

5、o required to vent air that is trapped during assembly.Evidence of Recurrence Control Effectiveness: As of this date, eight-six (86) Solid Rocket Motors (RSRM) have flown successfully and ten (10) full-scale RSRM test motors have been tested successfully since Challenger with no failures and no evid

6、ence of joint deterioration or burn-through. This successful record indicates that recurrence control has been successful.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): a71 Space Operationsa71

7、Exploration SystemsAdditional Key Phrase(s): a71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Launch VehicleAdditional Info: Approval Info: a71 Approval Date: 2001-07-23a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-