1、Lessons Learned Entry: 0192Lesson Info:a71 Lesson Number: 0192a71 Lesson Date: 1992-11-04a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: Orbiter Body Flap Description of Driving Event: Photoanalysis of the STS-28 (OV-102, Columbia) flight showed larger body flap deflection
2、s than were calculated. The flaps are in a turbulent flow field, which creates a hinge moment spectrum greater than that used in the structural fatigue analysis. The loads are all within the structural limits, but the fatigue analysis shows a reduction of allowable flights from 100 to 77.After the h
3、igher hinge moments were observed, additional ground tests were conducted using recalibrated strain gages on the body flap actuator as well as additional instrumentation on the rotors and stators. Three types of loads were applied. It was discovered that an additional load path existed back through
4、the driving gear to the supporting structure. The original equations assumed only four load paths at the actuators. With a fifth load path, it is necessary to develop a new set of equations. It also was discovered that the actuators were more flexible than originally assumed and that the OV-102 (Col
5、umbia) actuators were more flexible than those on OV-103 (Discovery) and OV-104 (Atlantis). This is attributable to increased tooth width on the OV-103 and OV-104 actuators. Additional tests are planned to further evaluate the body flap structure.Lesson(s) Learned: The results of flight tests indica
6、te that turbulent flow over the body flap induces greater stresses than originaly used for structural analysis.Recommendation(s): Evaluate as rapidly as possible, the results of new tests and loads analyses to reestablish the allowable number of flights for the body flap.Provided by IHSNot for Resal
7、eNo reproduction or networking permitted without license from IHS-,-,-Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phrase(s): a71 Flight Equipmenta71 Launch Vehiclea71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1994-06-06a71 Approval Name: James G. Klinea71 Approval Organization: KSC/HEIa71 Approval Phone Number: 407-867-7614Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
