1、Lessons Learned Entry: 1264Lesson Info:a71 Lesson Number: 1264a71 Lesson Date: 2002-07-01a71 Submitting Organization: LARCa71 Submitted by: Grant WatsonSubject: A Thorough Understanding of Model Mount (sting, arc sector, etc) Design Loads is Required by All Key Test Personnel Description of Driving
2、Event: While testing at Mach 0.8 in the 16-ft Transonic Tunnel, a full-scale F-15 inlet model separated from the sting. The model traveled downstream and impacted the catch screen and turning vanes. The impact resulted in total loss of the model and damage to the screen. Some debris got through the
3、screen and damaged the wind tunnel blades. The sting was also damaged. An investigation team concluded that the aerodynamic loads on the model resulted in sting loads that exceeded the ultimate strength of the sting. Possible reasons the large loads occurred are: operating at a Mach Number not in th
4、e original test envelope, F-15 cowl traveled past intended angle, sting deflection, and dynamic loads.THERE ARE 6 LESSONS IN LLIS FOR THIS DRIVING EVENT.Lesson(s) Learned: During the course of the investigation, the mishap board concluded that several key personnel did not have a thorough understand
5、ing of the model mount (sting, arc sector, etc) load limits. The personnel only knew the values, not the details behind them. This lack of understanding did not contribute to this mishap, but it could contribute to future mishaps if not addressed.Recommendation(s): A thorough explanation of model mo
6、unt (sting, arc sector, etc) load limits should be available and made to all facility personnel. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Evidence of Recurrence Control Effectiveness: Pretest and pre-run meetings are now in place along with a
7、check list that properly identifies and documents worst case test conditions and limits. Worst-case test conditions and failure mode analysis are now included as part of a new branch position “AST Facility Systems Safety Engineer“. This function specifically looks at test as a system to identify fai
8、lure modes or undesired events. Based on the failure scenarios, additional countermeasures or state-of-the-art analysis is performed prior to the Facility Safety Head approving test runs to begin. A thorough explanation of model mount (sting, arc sector, etc) load limits is explained and made availa
9、ble to all facility personnel. At the pretest meeting the Facility Safety Head identifies most highly loaded component in the sting and describes what condition causes the load.Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 2002-07-22a71 Approval Name: Leslie J. Johnsona71 Approval Organization: LARCa71 Approval Phone Number: 757-864-9409Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
