1、Lessons Learned Entry: 0039Lesson Info:a71 Lesson Number: 0039a71 Lesson Date: 1992-09-18a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: SSME Oxygen Lines Description of Driving Event: The mass SPEC is used to leak check the SSME heat exchanger (HEX) coil, to evacuate the
2、MPS fuel vacuum jacketed (VJ) lines and for external leak checks using the hand-held probe. The heat exchanger converts liquid oxygen to gaseous oxygen for pressurizing the shuttle external oxygen tank. The MPS fuel line vacuum jackets provide the insulation necessary to meet SSME pre-start pump inl
3、et temperatures. If mass SPEC vacuum is lost for any reason (power loss or belt breakage) vacuum roughing pump oil may be sucked into the SSME heat exchanger (back-streaming) unless the hex is isolated immediately.Lesson(s) Learned: Helium leak detector roughing pump failure during mass SPEC operati
4、on could cause contamination of SSME oxygen lines.Recommendation(s): Design and install vacuum controlled isolation valves that will prevent contamination of SSME oxygen lines, in the event of loss of pump vacuum.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: Provided
5、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 Flight Operationsa71 Flight Equipmenta71 Ground Operationsa71 Ground Equipmenta71 Hardwarea71 Launch Processa71
6、 Launch Vehiclea71 Parts Materials & ProcessesAdditional Info: Approval Info: a71 Approval Date: 1994-06-01a71 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-,-,-
