1、Lessons Learned Entry: 0502Lesson Info:a71 Lesson Number: 0502a71 Lesson Date: 1994-07-08a71 Submitting Organization: LARCa71 Submitted by: Bernard LewisSubject: External Thermal Barrier (ETB) Retainer as a Potential Single Point Failure Description of Driving Event: The National Transonic Facility
2、(NTF) is a transonic wind tunnel primarily intended to provide a high Reynolds Number test capability for aerodynamic research and the development testing of commercial and military aircraft configurations. On 1-18-89, the NTF experienced a Type A mishap, resulting in irreparable damage to all 25 fi
3、berglass fan blades, significant damage to the upstream nacelle region and minor damage to tunnel internals downstream of the fan. The mishap was initiated by local failure (due to fatigue and fracture damage) of the External Thermal Barrier (ETB) retainer, resulting in high energy release of damage
4、 causing metallic parts.The Mishap Investigation Board determined that one factor contributing to the mishap was the failure of the Safety Analysis Reporting System. The ETB was not treated as a critical assembly or as a critical item of the ntf drive system (i.e. It was not recognized as a single p
5、oint failure which could result in a Type A mishap). There were no inspection or maintenance requirements developed for the ETB retainer. A Safety Analysis Report (SAR) was not performed by either the contractor or NASA.Lesson(s) Learned: The Safety Analysis Report (SAR) System failed. If the ETB re
6、tainer had been identified as a potential single point failure, preventive measures could have been taken to prevent this mishap.Recommendation(s): This mishap was formally investigated, the failure causes identified, and actions recommended to be taken to prevent a like occurrence.Evidence of Recur
7、rence Control Effectiveness: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Facilitiesa71 Safety & Mission Assurancea71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 1997-04-02a71 Approval Name: Elijah C. Kenta71 Approval Organization: 421a71 Approval Phone Number: 757-864-3345Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
