1、Lessons Learned Entry: 0523Lesson Info:a71 Lesson Number: 0523a71 Lesson Date: 1994-08-23a71 Submitting Organization: LARCa71 Submitted by: Bernard LewisSubject: Failure in the 16 Transonic Tunnel During Testing of a Lockheed Designed Powered Turboprop Model Description of Driving Event: On October
2、29, 1985, a failure occurred in the 16 transonic tunnel during testing of a Lockheed designed powered turboprop model. The model failed while being tested at mach 0.8. The model propeller, spinner, balance, and air motor separated from the model nacelle and impacted the tunnel fan blades. The separa
3、ted model components were irreparably damaged and all except one of the tunnel fan blades were damaged.The investigating committee found the most probable cause of failure to be high dynamic loading due to loss of one or more prop blades. It was also found that:a71 The model design approach attempte
4、d to eliminate blade loss as a credible failure mode.a71 The consequence of blade failure was not considered by Langley, Lewis, or Lockheed.Lesson(s) Learned: Model integrity criteria should be developed and appropriate publications updated to require design consideration of blade loss, encapsulatin
5、g parts, accounting for dynamic loads and/or instabilities, and the identification of dynamic characteristics by analysis and/or tests.Recommendation(s): Based on the above findings, the investigating committee made the following recommendations:1. LaRC should develop model integrity criteria and up
6、date LHB 1710.15 to require design consideration of blade loss, encapsulating parts, accounting for dynamic loads and/or Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-instabilities, and the identification of dynamic characteristics by analysis and/
7、or tests.2. At least one reviewer of the model integrity report should be familiar with loads and instabilities of rotating systems.3. For each test, prepare and document test procedures including inspection requirements (for example, bearings) and operating checklists, and conduct wind-on and wind-
8、off rehearsals.4. Instrument for, and record dynamic and static loads data during testing necessary to insure model integrity and correlate these measurements with predictions used in analysis.5. For future high risk tests, consider installing screening to protect the wind tunnel fan blades.Evidence
9、 of Recurrence Control Effectiveness: After this incident, Lockheed made modifications to insure containment of all parts within the model should blade failure occur. After modification, a verification test proved the model capable of sustaining “blade out“ conditions.Documents Related to Lesson: N/
10、AMission Directorate(s): N/AAdditional Key Phrase(s): a71 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-,-,-
