1、Lessons Learned Entry: 0583Lesson Info:a71 Lesson Number: 0583a71 Lesson Date: 1998-02-19a71 Submitting Organization: JPLa71 Submitted by: K. Clark/D. OberhettingerSubject: Test Contingency Planning Should Consider Facility Power Interruptions (1996) Abstract: During a regional public service power
2、outage, an unplanned facility power loss occurred during system level thermal-vacuum test of the Mars Global Surveyor. This resulted in a slight inflow of external unfiltered air into the propulsion system through its Ground Support Equipment (GSE) pressure control system - a potential contamination
3、 concern. Test contingency plans and FMEAs for ground support equipment should consider responses to facility power interruptions. Test facilities should have devices to maintain a safe spacecraft environment in the event of a facility power loss.Description of Driving Event: Propulsion systems are
4、normally kept at a net positive pressure. During a regional public service power outage, an unplanned facility power loss occurred during system level thermal-vacuum test of the Mars Global Surveyor (MGS). This resulted in a slight inflow of external unfiltered air into the propulsion system through
5、 its Ground Support Equipment (GSE) pressure control system - a potential contamination concern. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-refer to D descriptionD MGS Prepared in Vacuum Chamber for System-Level Testing Examination of the propul
6、sion test equipment GSE revealed that an open port on its vacuum pump relief valve allowed a small amount of room air back through its cold trap. Had a separate GSE solenoid valve been included immediately downstream of this vacuum pump, the propulsion system would have been safe in the event of tot
7、al facility power failure. Because the backflow rate into the propulsion system was small and the cold trap temperature was not compromised, there was little concern for contamination. Gas sampling confirmed that there had been no significant contamination of flight hardware. Backup power was restor
8、ed within one minute, and the system resumed operation as designed.Reference(s): Problem/Failure Report No. B0PE10Lesson(s) Learned: Unplanned power interruptions during thermal-vacuum test may cause air backflow and possible contamination and/or damage of flight hardware.Recommendation(s): 1. Consi
9、der appropriate responses to facility power interruptions when developing test contingency plans and failure mode and effects analyses (FMEAs) for ground support equipment.2. Consider equipping test facilities with GSE devices which maintain a safe spacecraft environment in the event of facility pow
10、er loss.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Energya71 Test & Verificationa71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 1998-03-03a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
