1、Lessons Learned Entry: 0018Lesson Info:a71 Lesson Number: 0018a71 Lesson Date: 1991-07-30a71 Submitting Organization: JSCa71 Submitted by: Leroy UnderwoodSubject: Eddy Current Inspection for Cracks in Flight Hardware Components (Shuttle Orbiter Brake Retainer Washers) Description of Driving Event: T
2、he shuttle orbiter right hand inboard brake failed during the STS-7 landing, even though there was very little braking action. A post-flight tear down and evaluation of the brakes determined the cause of the failure to be defective retainers (washers), which hold together the carbon lining and the c
3、arrier plate. These retainers are made from Titanium/Zirconium/Molybde-Num (TZM), which is very resistant to high temperature and very brittle. Numerous cracked retainers were found during the inspection. The cracks, in many cases, were not perceptible with the human eye and were only detected by Ed
4、dy Current inspection. The retainers were visually inspected and replaced as required before the STS-7 flight. As corrective actions, the supplier implemented the use of a different riveting tool to minimize cracks and a change in the inspection procedure to include a 100% use of the Eddy Current in
5、spection technique.Lesson(s) Learned: Cracks in components of critical flight hardware may go undetected during pre-flight visual inspection and can lead to hardware failure and equipment damage.Recommendation(s): The supplier implemented the use of a different riveting tool and a change in the insp
6、ection procedure to include the use of the Eddy Current inspection technique.Evidence of Recurrence Control Effectiveness: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration Syst
7、emsa71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Aircrafta71 Flight Operationsa71 Flight Equipmenta71 Hardwarea71 Launch Vehiclea71 Parts Materials & ProcessesAdditional 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-,-,-
