When I've been inside the fuselage of a real commercial airliner, whenever the we're preparing to takeoff, I've always heard those flaps being extended or lowered. The sound is usually fairly loud but FSX doesn't include that. And landing gear is usually very easily heard and felt but FSX doesn't include that.
Are there soundsets out there for these components?
I'm not sure where you audio are set, but I here them quite well. The 737 it is hard to hear, but there. Try the DC-3 (flaps sound like a whine) or any of the twin props - you will here flaps and gear.
I've heard the click that occurs when you first hit the switches, but shouldn't there be a long hydraulic whine while they're being extended, in the larger commercial airliners like the A320, 737... no?
The bigger the jet, the further the cockpit is away from the flaps. What you hear in the cabin is diferent from whatyoumight hear in the cockpit.
Wextend your flaps and retract them while you're at the gat with the engines idling; you should hear them easily.
You should be able to find something you like on the following pages. Just browse through the File descriptions ➡