REG NASA-LLIS-0015-1993 Lessons Learned - Torque Requirements Aligned to Fitting Sizes.pdf

1、Lessons Learned Entry: 0015Lesson Info:a71 Lesson Number: 0015a71 Lesson Date: 1993-07-24a71 Submitting Organization: JSCa71 Submitted by: S. MartinSubject: Torque Requirements Aligned to Fitting Sizes Description of Driving Event: Hydraulic fluid leakage was noted at the interface of the flex hose

2、and Rosan fitting on a hydraulic pump. The fittings were a different size at each end of the flex hose. Different size fittings require different torque values, which the specifications did not identify. The hydraulic system is inspected prior to each mission of the shuttle vehicle. Review of the pr

3、ocedure used during installation of the hydraulic system shows that one end of the flex hose was torqued to 120 foot pounds. The installation drawing does not specify that the other end of the flex hose has a smaller fitting that should require a lower torque. Leakage was corrected by a hose replace

4、d and torqued properly.Lesson(s) Learned: Failure to call out proper torque requirements for fittings with different sizes caused a hydraulic leak in a critical orbiter system.Recommendation(s): Inspections are performed prior to flight to check the flex hose connections for proper torquing and for

5、the absence of leaks.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Facilitiesa71 Fire Protectiona71 Ground Ope

6、rationsa71 Hardwarea71 Industrial Operationsa71 Parts Materials & Processesa71 SpacecraftAdditional 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-,-,-