[dholter]

Only problem is the Boeing Bombers from WWII did not have hydraulic landing gear. On both the B-17 and B-29 the gear is driven up and down by an electric motor and lead screw so Hydraulic failure would not affect gear operation. Same for flaps. Both aircraft carried a crank very similar to an inertia starter crank, in the event of damaged or motor failure they could be disengaged and the crew chief could manually crank them down. This is normally accessed in the bomb bay.

Thanks for the clarification S.Wire, then I'm talking about an electrical failure.