Boeing 737-900 Flaps

Today when starting a flight, I realized the sound for putting down flaps can only be heard when engines are on. Is this intentional? Is anyone else having the same problem with other aircraft?

That should be normal. Since flaps I believe uses electricity, it technically shouldn’t work unless there is power to the aircraft


even with ground power?


Normally the aircraft flaps are put down for departure when the aircraft is pushed back. By then atleast 1 engine would be running. In all of my irl flights, the flaps are put down after both engines are running.

However, you can put down your flaps once 1 engine is running as it requires power and hydraulics for that.



thank you all. i’m an idiot.

No you’re not! There are no silly questions in here. We are all living and learning. :)
Glad your question got resolved though.

PS: there are aircraft that exist (not in the sim though) where flaps are manually extended and retracted by means of a handle or bar in the cockpit. Just a little nugget of information :)


Absolutely not! It’s all a learning phase. We were all there once. Glad to help you!