1、Lessons Learned Entry: 0934Lesson Info:a71 Lesson Number: 0934a71 Lesson Date: 2000-06-16a71 Submitting Organization: MSFCa71 Submitted by: Tom HartlineSubject: SSME 0523 Test 902-772 Major Mishap Description of Driving Event: Space Shuttle Main Engine (SSME) test 902-772 was conducted Friday, June
2、16, 2000, on engine 0523 with High Pressure Fuel TurboPump (HPFTP/AT) 8109R1, and High Pressure Oxidizer Turbopump (HPOTP/AT) 8308. The test was prematurely cutoff at 5.2 seconds due a violation of the High Pressure Fuel Turbine (HPFT) temperature limit of 1860 degrees Rankine. The high temperature
3、led to High Pressure Fuel Turbopump turbine damage and the declaration of a type A mishap.The major objective of this test was to characterize the effects of Chamber Coolant Valve (CCV) position on HPFT temperature. Engine 0523 was in the Block Ia configuration (small throat Main Combustion Chamber)
4、 with the exception of the Pratt eventually reaching approximately 16 Grms on the pump end and 83 Grms on the turbine end. At 5.04 seconds, the HPFT DS T Launch Commit Criteria (LCC) was activated. At 5.08 seconds, 2 Failure Identifications (FIDs) were issued indicating that HPFT DS T CH A2 and HPFT
5、 DS T CH A3 had exceeded the 1860 degree Rankine redline. These FIDs were accompanied by a Major Component Failure (MCF) indication. The Facility Command and Data Simulator (CADS) was set to respond to an MCF indication before 6.6 seconds with a command to perform engine shutdown. The CADS unit issu
6、ed a shutdown command and the engine entered shutdown phase at 5.18 seconds. The engine powered down nominally with the exception of the HPFTP. Its spindown was much faster than nominal. It stopped at approximately 4 seconds after shutdown (expected for a pump with severe imbalance).Lesson(s) Learne
7、d: 1. Early on in the investigation there was much concern regarding the lack of damage to the FPB faceplate. Past failures in the FPB injector and OPB injector suggested that faceplate damage was common for fuel flow loss due to contamination. Model analysis performed during this investigation sugg
8、ests that with a short-duration test and with the fuel cavity contamination type and quantity observed, damage to the FPB faceplate does not necessarily occur. In other words, there exists a substantial range of contamination levels within which it is possible to Provided by IHSNot for ResaleNo repr
9、oduction or networking permitted without license from IHS-,-,-effectively destroy the HPFTP without melting the FPB faceplate. This conclusion is supported not only by the post-test hardware inspections from this test, but also by mathematical modeling analysis performed by MSFC and Rocketdyne.2. Th
10、e Pratt & Whitney HPFTP/AT has shown that it can endure extreme levels of imbalance and damage without engine catastrophic results.Recommendation(s): 1. Verify that all systems are free of foreign object debris prior to hot-fire. Limit the opportunity for contamination introduction by minimizing the
11、 use of potential contaminants and using permanent closures on joints were applicable. Keep joints closed at all times when access is not required to perform work.2. Implement an improved method of dealing with loose, non-serialized materials to ensure full accountability. Additional inspections and
12、 checkouts should be considered to verify that the engine is contamination free, prior to any hot-fire.3. The use of reusable joint barriers, which can be controlled and accounted for, should be investigated.4. Provide clear instructions in processing paperwork and discrepancy paperwork. Use positiv
13、e identification of engine hardware to ensure that the work is being done on the correct part.5. Correct electronic paperwork systems, to either prevent changes or provide a clear tracking of change activities. Further ensure that all SSME changes can be tracked.6. SSME Project should investigate ev
14、idence to ensure that SSME 0523 Powerhead structural properties were adequate. Ensure that an unacceptable condition does not exist in the flight fleet.7. The SSME Project should understand the mechanism causing roller bearing failure and ensure that conditions experienced were outside the designed
15、capability of the roller bearing.8. The agency and its contractor teams need to avoid schedule practices that create undue risks.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics ResearchAdditional Key Phra
16、se(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Facilitiesa71 Hardwarea71 Mishap Reportinga71 Safety & Mission Assurancea71 Spacecrafta71 Test Articlea71 Test & VerificationMishap Report References: SSME 0523 Test 902-772 Failure Investigation Final ReportAdditional 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-,-,-
