NASA-LLIS-0028
Lessons Learned - Extension of Orbiter Access Arm (OAA)
| Organization: | NASA |
| Publication Date: | 11 September 1992 |
| Status: | active |
| Page Count: | 2 |
scope:
Description of Driving Event:
Failure of relay K41 to activate or relay K44 to deactivate will disable hardwire safing panel control of both the primary and secondary extend pilot valves A101409 and A101410. The command path for the hardwire safing circuits, which controls the orbiter access arm, runs through these relays. If relay K41 fails to activate or relay K44 fails to deactivate, the OAA would not extend. If a failure occurs, the hardwire safing system would not activate the extension circuit and emergency reextension could not be accomplished.
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