REG NASA-LLIS-0020-1991 Lessons Learned - Debris Causing Component Failure in a Critical Piece of Crew Equipment (Shuttle Orbiter Launch Entry Coverall Pressurization System).pdf

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1、Lessons Learned Entry: 0020Lesson Info:a71 Lesson Number: 0020a71 Lesson Date: 1991-08-22a71 Submitting Organization: JSCa71 Submitted by: Leroy UnderwoodSubject: Debris Causing Component Failure in a Critical Piece of Crew Equipment (Shuttle Orbiter Launch/Entry Coverall Pressurization System) Desc

2、ription of Driving Event: A dual suit pressure controller failed to pressurize a crew coverall during manned suit testing and the shuttle flight STS-37 Terminal Countdown Demonstration Test (TCDT). The coverall is donned by an orbiter crew member during launch and entry. No previous failures of this

3、 type had occurred before. Upon disassembly of the suit, a small piece of fabric reinforced elastomer material (from a seal called a neck dam that separates the head and torso parts of the coverall) was found lodged inside the controller on the primary diaphragm assembly seat. Before the TCDT, a rap

4、id replacement of the neck dam was performed. The usual, but undocumented, step in the replacement procedure that called for component removal before changing the neck dam did not occur. The piece of elastomer from the old neck dam remained in the suit as debris and migrated to the diaphragm during

5、the pressure cycling. The corrective actions included: (1) documenting the procedural steps to require component removal, (2) protecting the component area from debris by adding plastic sheeting, and (3) vacuuming the inner volume of the coverall and inspecting it following all maintenance work. A f

6、ailure of a coverall of this type during flight could result in the loss of the crew member if cabin pressurization failed.Lesson(s) Learned: Lack of debris protection for critical components during maintenance can result in potentially catastrophic component failures.Recommendation(s): Corrective a

7、ctions included:(1) documenting the procedural steps to require component removal, (2) protecting the components with plastic sheeting, and (3) vacuuming and inspecting the inner volume Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-of the coverall.

8、Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Flight Operationsa71 Flight Equipmenta71 Parts Materials & Processesa71 Personal Protective Equipm

9、enta71 Spacecrafta71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1993-09-10a71 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-,-,-