1、Lessons Learned Entry: 0933Lesson Info:a71 Lesson Number: 0933a71 Lesson Date: 2001-04-05a71 Submitting Organization: LARCa71 Submitted by: Grant WatsonDescription of Driving Event: A failure occurred at the Transonic Dynamics Tunnel (TDT) when a blade separated from a rotor (i.e., an airplane prope
2、ller). The incident did not result in damage to the TDT, but significant damage occurred to the Wing and Rotor Aeroelastic Testing System (WRATS). This is a reusable testbed placed inside the TDT test section that allows for testing different rotor models. The rotor model being tested at the time wa
3、s not NASA owned; it had been designed and manufactured by an industry customer.A thorough investigation concluded that the most likely cause was using the wrong material to fabricate the cuffs of the rotor model. A cuff is the mechanism that attaches a blade to the rotor hub. The model designer spe
4、cified aluminum 7075-T7351 as the cuff material, but the part was actually fabricated using aluminum 6061. The stress analysis performed prior to testing indicated that 7075 had the proper material properties for the cuffs intended ! task. However, an examination of the properties of 6061 showed tha
5、t a cuff manufactured from 6061 was, “marginal at best for the task intended.“It was clear that the material change was not properly analyzed and that some of the people who needed to be informed about the change had not been informed. The customer stated after the incident, “that the material chang
6、e was approved, but that information was not incorporated into the original stress analysis.“Lesson(s) Learned: When failure of a customers model can cause damage to a test facility, the appropriate quality assurance requirements must be placed upon the customer.When making a material substitution,
7、the stress analysis needs to be recalculated using the substitute material.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): Facility Manager / Facility Safety Head needs to ensure quality assurance requirements are placed upon custo
8、mers testing in a NASA facility.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Configuration Managementa71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 2001-04-30a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
