My training notes also tell me that there are 3 position sensors (RVDTs) in the flap
lever. The median position of these sensors is used for flap control. If two sensors have failed, flaps will only work in Alternate mode (according to my notes). With only Standby Power available, it
seems that only one of these flap lever position sensors is powered.
Therefore, it seems, no flap movement during Standby Power ops.
Strikes me as odd, however, that aircraft logic is preventing you from using something which is essentially usable.
