1、Lessons Learned Entry: 0467Lesson Info:a71 Lesson Number: 0467a71 Lesson Date: 1995-06-14a71 Submitting Organization: LERCa71 Submitted by: Judy TerlepSubject: Centaur RL10 Rocket Engine Check Valve - Atlas/Centaur Program Description of Driving Event: On August 22, 1992 an Atlas/Centaur Launch Vehi
2、cle (Atlas 1, Launch AC-71) carrying a Hughes Galaxy I-R Spacecraft was destroyed in flight. The Centaur C-1 engine had failed to achieve full thrust, resulting in an uncontrolled tumble of the vehicle. The guidance system, sensing that the vehicle had not achieved proper acceleration, shutdown both
3、 engines and instituted a restart sequence. Once again the C-1 engine failed. Full thrust was achieved by the C-2 engine both times. In lieu of the C-1 thrust failure the vehicle was destroyed by the range safety officer.To start reliably, the RL10 engine requires proper fuel and oxidizer pressure a
4、t its pump inlets and the fuel and oxidizer pumps to be at the proper cryogenic temperature. The engine temperature results from a two-stage chilldown process. The prelaunch chilldown is provided by ground dewars supplying pressurized helium. Each RL10 engine receives the flow of helium through a ch
5、eck valve. These valves should close when the flow is terminated to prevent further flow of any gas through the engine via the chilldown ducts exiting the vehicle. The state of the chilldown check valve was not monitored. As a result, the check valve of the C-1 engine was not closed and an ingestion
6、 of air occurred which eventually caused the engine to fail.The investigation team also concluded that AC-70s failure is due to the same cause as AC-71. For more information on AC-70, see AC-70 Anomaly Investigation Summary Report. Further details on the AC-71 failure are found in the AC-71 Anomaly
7、Investigation Summary Report.Lesson(s) Learned: If the check valve on the Centaur RL10 rocket fails to close, an ingestion of air can occur. Solidification of this air will prevent the engine turbopump from rotating causing engine failure.Provided by IHSNot for ResaleNo reproduction or networking pe
8、rmitted without license from IHS-,-,-Recommendation(s): 1. Change the design process to include a cause/effect methodology.2. Conduct corrective action to prevent air ingestion.3. Improve system margins with several procedural changes.Evidence of Recurrence Control Effectiveness: Changes were made t
9、o the failure analysis process of flight anomalies.Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 Launch VehicleAdditional Info: Approval Info: a71 Approval Date: 1996-10-25a71 Approval Name: Sell Jamesa71 Approval Organization: 501-4a71 Approval Phone Number: 216-433-8618Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
