REG NASA-LLIS-0148-1992 Lessons Learned - Reaction Control System (RCS) Thruster Valves.pdf

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1、Lessons Learned Entry: 0148Lesson Info:a71 Lesson Number: 0148a71 Lesson Date: 1992-10-02a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: Reaction Control System (RCS) Thruster Valves Description of Driving Event: Leakage of small quantities of toxic propellants, monomethyl

2、 hydrazine (MMH) and nitrogen tetroxide (N2O4) from one or more reaction control system (RCS) thrusters could create an environment hazardous to personnel. The aft and forward RCS contain residual MMH and N2O4 under post-flight pressure. RCS thrusters have been known to leak when ambient temperature

3、 is low, orbiter valve pressure is low, and/or if there is no orbiter internal purge.Lesson(s) Learned: RCS thruster valve seats have a tendency to relax at low temperatures and low pressure, allowing liquid/vapor to leak past the seals.Recommendation(s): To minimize the potential for a significant

4、leak of hypergolic propellants, ensure that dual valve isolation is maintained.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Mission Directorate(s): a71 Space Operatio

5、nsa71 Exploration SystemsAdditional Key Phrase(s): a71 Flight Equipmenta71 Ground Operationsa71 Hazardous/Toxic Waste/MaterialsAdditional 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-,-,-