1、Lessons Learned Entry: 0266Lesson Info:a71 Lesson Number: 0266a71 Lesson Date: 1993-07-07a71 Submitting Organization: JSCa71 Submitted by: John McGeeSubject: Seal Manufacturing Design and Inspection Error (Indirect Measurement of Critical Dimensions) Resulted in Material Yielding Description of Driv
2、ing Event: A K-Seal drawing and manufacturing instruction specified measurement of inner and outer diameters, but no measurement of the K-Seal legs. Following the failure of a batch of seals during an Acceptance Test Procedure (ATP), an investigation revealed that they had all yielded and provided i
3、nsufficient sealing forces. The yielding was caused by thin leg sections that occurred due to no direct measurement of leg thickness during manufacturing. Failure of this K-Seal could result in hot high pressure oxygen leakage during the orbiter launch phase with its associated hazards and also a la
4、ck of sufficient oxygen for external tank autogenous pressurization. Note: A drawing of the subject seal is available with the source documentation.Lesson(s) Learned: Critical dimensions, measured indirectly during inspection, may allow for excessively thin material, resulting in permanent yielding
5、and component failure.Recommendation(s): For this component, the manufacturing and tooling process was revised to add direct measurements of critical dimensions during inspection.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: Provided by IHSNot for ResaleNo reproductio
6、n or networking permitted without license from IHS-,-,-N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Flight Equipmenta71 Ground Operationsa71 Hardwarea71 Safety & Mission AssuranceAdditional Info: Approval Info: a71 Approval Date: 1993-09-13a71 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-,-,-
