1、Lessons Learned Entry: 0172Lesson Info:a71 Lesson Number: 0172a71 Lesson Date: 1992-10-22a71 Submitting Organization: KSCa71 Submitted by: David PenningtonSubject: Orbiter Access Arm (OAA). Description of Driving Event: Pilot actuated extend supply and return valves can be reset to the closed positi
2、on while the access arm is being extended. This could damage the OAA and possibly prevent reextension and crew egress. Position of arm must be monitored during launch countdown. A retract signal from LPS or from the safing panel during an LPS emergency extend mode will cause the extend valves to be
3、reset. In addition, removing the safing panel emergency extend signal prior to full extend, while the LPS or safing panel is in the retract mode, will cause the extend valves to reset.Lesson(s) Learned: Sudden deceleration of the arm and entrapment of pressurized hydraulic fluid may cause damage to
4、the OAA and prevent crew rescue/egress.Recommendation(s): Ensure that the position of the arm is monitored during launch countdown; initiate a countdown hold if the arm is retracted prior to T-0 seconds.Evidence of Recurrence Control Effectiveness: N/AProvided by IHSNot for ResaleNo reproduction or
5、networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Facilitiesa71 Ground Operationsa71 Ground Equipmenta71 Launch Processa71 Risk Management/AssessmentAdditional Info: Approval Info: a71 Approval Date: 1994-06-06a71 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-,-,-
