scope:

Description of Driving Event:

Pilot actuated extend supply and return valves can be reset to the closed position 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 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.