1、Lessons Learned Entry: 1006Lesson Info:a71 Lesson Number: 1006a71 Lesson Date: 1997-02-01a71 Submitting Organization: HQa71 Submitted by: David M. LengyelSubject: Space Shuttle Program/Block II Space Shuttle Main Engine (SSME)/Test & Verification to 109% Power Level Description of Driving Event: Cer
2、tification of Block II SSME Testing at 109% for Intact Abort ScenariosLesson(s) Learned: The Block II engine will be certified for operation at 109% power level only for abort situations. Accordingly, the test program provides only limited cumulative test time at this thrust level.Recommendation(s):
3、 After completion of the current planned Block II certification test program, conduct a certification extension test program that will demonstrate the highest thrust level for safe continuous operation achievable by the Block II configuration. This program should attempt to achieve at least the 109%
4、 power level.Evidence of Recurrence Control Effectiveness: The Block II program was developed to “improve the safety, reliability, and robustness of the SSME“ by providing lower operating temperatures, pressures, shaft speeds, and other critical parameters. An increase in operating power level from
5、104% to 104.5% will offset some of the weight gain of Block II. The Block II SSME was never intended to increase Space Shuttle ascent performance or increase payload capability to orbit. However, additional performance has been accepted for a few specific missions at the cost of some of the improved
6、 safety margin. There is a commitment that the ISS flights will provide 106% engine power level certification to achieve mandatory critical payloads to orbit. The Block II certification will also provide a 109% intact abort Provided by IHSNot for ResaleNo reproduction or networking permitted without
7、 license from IHS-,-,-capability, which will allow the vehicle system to better optimize abort scenarios. Implementation recommendations for use of 109% throttle for intact aborts will be made by the Shuttle operations element once certification is complete.Documents Related to Lesson: N/AMission Di
8、rectorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phrase(s): a71 Aerospace Safety Advisory Panela71 Policy & Planninga71 Safety & Mission Assurancea71 Spacecrafta71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 2001-11-01a71 Approval Name: Bill Loewya71 Approval Organization: QSa71 Approval Phone Number: 202-358-0528Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
