1、Lessons Learned Entry: 0176Lesson Info:a71 Lesson Number: 0176a71 Lesson Date: 1992-10-23a71 Submitting Organization: KSCa71 Submitted by: Lisa L. MusgraveSubject: Solid Rocket Motor (SRM) Field Joints and Configuration Description of Driving Event: The primary reason for the use of the putty in the
2、 SRM was to act as a thermal barrier in the joints to prevent o-ring erosion resulting from circumferential hot gas flow during motor firing. Prior to the 51-L mishap, the putty was believed to perform such that it would allow pressure to the primary o-ring during the SRM ignition transient. Subsequ
3、ently, it has been found that humidity and temperature enhance the characteristics of putty relative to its pressure holding characteristics. The uncertainty of these characteristic changes directly affected the ability of the field joint to seal.Lesson(s) Learned: 1. Insufficient knowledge of perfo
4、rmance characteristics of putty used as a thermal barrier in SRM field joints affected ability of joints to seal.2. During testing, putty preparation differed from that used on flight hardware resulting in SRM lacking liftoff dynamic effects on case joints.Recommendation(s): 1. Design a new SRM fiel
5、d joint which eliminates the use of putty as a thermal barrier.2. Configuration and processes during qualification testing must be as similar to actual performance as possible in order to verify adequacy.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-
6、,-Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Flight Equipmenta71 Hardwarea71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1994-06-06a71 Approval Name: James G. Klinea71 Approval Organization: KSC/HEIa71 Approval Phone Number: 407-867-7614Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
