Hellcat flap mechanism

Squadron Signal Walk Around Number 9- F6F Hellcat; states on page 23:

"The flaps on the F6F-3 are hydraulically actuated via the engine driven hydraulic pump. By use of a manual selector valve, the flaps can still be operated after an electrical failure. They can also be lowered by use of hydraulic hand pump. It takes some thirty-five cycles of the hand pump to extend the flaps, and twenty-five to retract them."

...so - in normal operation they are electrically switched and hydraulically driven, with a manual hydraulic pressure backup for emergency operation.