REG NASA-LLIS-0059-1992 Lessons Learned - RCS Thruster Heater Power During Ferry Flight Stopovers RCS Thruster Ferry Plug Removal Hypergol Exhaust System Indicator Lamp.pdf

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1、Lessons Learned Entry: 0059Lesson Info:a71 Lesson Number: 0059a71 Lesson Date: 1992-02-12a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: RCS Thruster Heater Power During Ferry Flight Stopovers; RCS Thruster Ferry Plug Removal; Hypergol Exhaust System Indicator Lamp Descrip

2、tion of Driving Event: During the removal of the flight reaction control system (RCS) ferry plugs from the orbiter, between 1/4 and 3/4 cup of monomethylhydrazine (MMH) fuel spilled from the thruster. The liquid contacted the gloves and right shoe of the technician pulling the plug. The RCS thruster

3、 valve seals have a history of sensitivity to temperatures below 60 deg F. To limit the potential for leakage, the RCS thruster heater power unit should remain on throughout the Dryden Flight Research Facility (DFRF) safing and ferry period, including flight stopovers and KSC offload.Lesson(s) Learn

4、ed: 1. Failure to power up the orbiter during ferry flight stopovers disables the thruster heaters and increases the potential for RCS thruster leakage.2. Propellant may spill out of RCS thrusters if they are not aspirated prior to plug removal.3. Due to an excessively slow panel lamp, the exhaust s

5、ystem was actuated several times and resulted in the system remaining off.Recommendation(s): 1. Develop detailed guidelines as to when the orbiter can be powered down or when it must remain powered up.2. To preclude spillage of propellant during plug removal from a leaking thruster, the plug should

6、be aspirated through the relief valve.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3. Add a flashing red light that responds without delay indicating system is operating.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson:

7、 N/AMission Directorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phrase(s): a71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Flight Operationsa71 Flight Equipmenta71 Ground Operationsa71 Ground Equipmenta71 Hardwarea71 Hazardous/Toxic Waste/Materialsa71 Launch Vehiclea71 Safety & Mission AssuranceAdditional Info: Approval Info: a71 Approval Date: 1994-06-02a71 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-,-,-