1、Lessons Learned Entry: 0966Lesson Info:a71 Lesson Number: 0966a71 Lesson Date: 1995-05-15a71 Submitting Organization: MSFCa71 Submitted by: Billy Cole / RetiredSubject: Space Shuttle Main Engine (SSME): Fuel System Oscillations Description of Driving Event: After the main fuel valve starts to open,
2、three oxidizer valves in the SSME are separately subjected to a series of position commands to precisely control oxidizer system priming times for the three combustors. The first oxidizer valve to be commanded is the fuel preburner oxidizer valve (FPOV). After a delay of 0.100 seconds, the FPOV is r
3、amped to 56 percent open at its maximum skew rate. At 0.72 seconds, the FPOV is given a “notch“ command to close about 10%. Just prior to the third fuel system oscillation, second “notch“ command is given.Lesson(s) Learned: Fuel system oscillations can be reduced during the startup phase by closely
4、controlled engine priming sequence.Recommendation(s): Reduce two-cycle-per-second oscillations in the fuel system by issuing a 10% “notch“ -closing command to the fuel preburner oxidizer valve at a specified time in the startup sequence.Evidence of Recurrence Control Effectiveness: The Space Shuttle
5、 Main Engines have operated successfully in over 68 flights. Although many minor changes have been made to improve performance and reliability, this lesson learned or feature described has continued to sustain reliable performance in over 200 flight performances of individual engines.Documents Relat
6、ed to Lesson: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N/AMission Directorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phrase(s): a71 Configuration Managementa71 Cryogenic Systemsa71 Ground Equipmenta71 Hardwarea71 Launch
7、Vehiclea71 Parts Materials & Processesa71 Safety & Mission Assurancea71 Spacecrafta71 Test Articlea71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 2001-07-23a71 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-,-,-
