To: Radar Contact
You bring up a good point about turning off two hydraulic systems and then troubleshooting the problem but being unfamiliar with the electrical set-up at the aircraft level I ask the following. By pulling the WTB CBs it would seem to me that you would disable the WTBs and not turn them on.
In my estimation the most dangerous situation is to have the flaps extend at cruise speed which could result in the loss of the flaps and serious damage to the wing structure. At this time the Command sensor unit is in the “Off” condition and as such the computer is sleeping and can not command a corrective action. If in fact the wing tip brakes are set by the computer the PCU is still driving and the torque limiters will lock up the system. However when this same situation occurred on the slat iron bird the wing tip brakes did not lock up. If the slats were commanded out during cruise flight the oncoming air loads would keep them from extending. However the flaps have the assistance of the oncoming air flow which would assist the flaps in extending adding to the effort created by the internal leak or computer malfunction.
The manufacturer of the Flap/Slat computer did not perform a correct FMECA as required by contract and as such there was no examination of the potential failures in the monitoring and control circuits. This may have contributed to the inability of the computer to counter the runaway slats on the iron bird. Also on the first revenue flight of an A-310 (Lufthansa) from Frankfurt to Cairo the pilot could not retract the flaps and had to return to Frankfurt with the flaps extended. The computer was totally ignorant of the failure and could not provide any corrective action on the “dolls eyes”. Naturally he had to fly at a very slow speed as compared to cruise flight.
