1、Lessons Learned Entry: 0152Lesson Info:a71 Lesson Number: 0152a71 Lesson Date: 1992-10-08a71 Submitting Organization: KSCa71 Submitted by: Lisa L. MusgraveSubject: Reaction Control System (RCS) Primary Thruster Plug Assembly Description of Driving Event: The RCS primary thruster throat ferry flight
2、plug assembly is used to prevent moisture intrusion during the orbiters ferry operations. This assembly is installed after the orbiter lands and is removed during deservicing operations. After deservicing, the primary engine cover is used during orbiter processing to control and/or prevent moisture.
3、 This cover has a butyl rubber o-ring which acts as a moisture seal, but is incompatible with N2O4. Vapor leakage could cause deterioration of the o-ring, severely limiting the effectiveness of the thruster ferry plug to seal out moisture, as well as contaminating the thruster nozzle.Lesson(s) Learn
4、ed: Nitrogen tetroxide (N2O4) vapor leakage from primary thruster causes o-ring deterioration, allowing moisture to enter/contaminate thruster nozzle.Recommendation(s): Install an o-ring seal compatible with nitrogen tetroxide that will prevent hypergolic leakage and water intrusion.Evidence of Recu
5、rrence Control Effectiveness: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 Parts Materials & ProcessesAdditional 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-,-,-
