REG NASA-LLIS-0013-1991 Lessons Learned - Fluid Sampling Techniques for Spacecraft Ground Support Equipment (Auxiliary Power Unit).pdf

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1、Lessons Learned Entry: 0013Lesson Info:a71 Lesson Number: 0013a71 Lesson Date: 1991-07-16a71 Submitting Organization: JSCa71 Submitted by: Leroy UnderwoodSubject: Fluid Sampling Techniques for Spacecraft Ground Support Equipment (Auxiliary Power Unit) Description of Driving Event: The gaseous nitrog

2、en service coupling of the shuttle orbiter Auxiliary Power Unit (APU) #2 fuel tank was found to be leaking after servicing for shuttle mission STS-3. It was determined that this leakage was the result of contamination/corrosion at the ground/airborne Quick Disconnect (QD). The probable source of the

3、 contamination was believed to be a stainless steel filter in the Ground Support Equipment (GSE). Moisture being trapped and held between the filter and its support screens had corroded the filter elements thereby causing the filter to fail and allowing contamination to migrate to the QDs where it w

4、as deposited on the poppet seat. Sampling of the fluid had been conducted at the GSE cart upstream of the filter. Investigation has shown that there are many types of contamination and corrosion present in the QDs. Leaking of nitrogen from the APU fuel tank could potentially result in the inability

5、to restart the APU for orbiter re-entry. The following actions were proposed to resolve this problem: (1) modification of the Ground Support Equipment (GSE) to provide for fluid sampling at the GSE/airborne interface, and (2) change the procedures to require filter inspection and replacement on a re

6、gular basis.Lesson(s) Learned: Incorrect sampling techniques for spacecraft Ground Support Equipment (GSE) fluid that fail to preclude downstream contamination can potentially damage critical flight hardware.Recommendation(s): Proposed actions to resolve this problem were: (1) modification of the GS

7、E to provide for fluid sampling at the GSE/airborne interface, and (2) require filter inspections and replacement on a regular basis.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Evidence of Recurrence Control Effectiveness: N/ADocuments Related to

8、 Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Configuration Managementa71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Ground Operationsa71 Ground Equipmenta71 Hardwarea71 Launch Vehiclea71 Parts Materials & Processesa71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1993-09-27a71 Approval Name: Ron Montaguea71 Approval Organization: JSC/NS3a71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-