Hello. I was watching a youtube vid of a 777 getting ready to depart. While taxiing, I noticed a sound that seemed to occur when it was turning. I thought at first it was the flaps lowering, but that's definitely not it.

If you care to hear the sound I'm talking about, you can click this youtube link. There's a VERY CLEAR example of the sound starting at 11'53" on the video, which lasts for several seconds.

What is this and is this common to all airline type jets? I'm very curious to know.

I also noticed the high speed aileron retracts with the flaps. It also was quite active (moving around a lot throughout the T/O and climb out). It was a big, sturdy piece with quite a bit of housing underneath it. Is this because such a sturdy piece is needed to support such a massive jet? And is it common to have it move around a lot during flight?

Thanks,
James

https://www.youtube.com/watch?v=1JUK-eQUMmc

 

Sounded like the Air Driven Hydraulic pumps on the Center System...Vented on the left side aft of the wing...They are a secondary system that helps with high system demand...they come on automatically or when manually selected...

The flight control system is fly by wire...the Flaperon will do what it needs to do to make the airplane do what is commanded. The outboard locks above 250KIAS. Lock is a bad word, but easier to explain...

Hope that helps....Cheers.

 

Indeed, and I understand. Thank you very much for the info!