What are the various whine noises coming from the Boeing 787 cabin? Especially near the wing. I have seen tons of YouTube videos in which it has a noise during takeoff, or when flaps are being lowered or raised?
5$\begingroup$ the flap motors? $\endgroup$– caseyOct 21, 2015 at 1:16
$\begingroup$ Yeah, the noises while the flaps are being extended or retracted are just the actuators for the flaps. During the takeoff run would be something else. The latter might be the notorious supersonic blade tip buzzsaw sound, especially if it's using the Trent engine rather than the GE engine. I've heard that in several Trent-powered 787 takeoff videos. $\endgroup$– reirabOct 21, 2015 at 1:27
$\begingroup$ @reirab, if you watch the first couple of seconds in this video you will here a really high pitch frequency from the 787, what is that actually? link also at 1:32 you here this other noise $\endgroup$– Techno04335Oct 21, 2015 at 1:49
3$\begingroup$ @Techno04335 It's probably best if you can keep each question about one particular thing and preferably link a video or two that demonstrates what you're referring to (like you did in the comment,) ideally with the time of the video you're asking about. In general on StackExchange sites, we like to keep each question to just one answerable question. $\endgroup$– reirabOct 21, 2015 at 2:14
10$\begingroup$ @casey "The passengers." $\endgroup$– voretaq7Oct 21, 2015 at 2:22
Other people have complained about this too. Boeing should rename the type to the "Whineliner".
The noise is caused by a hydraulic pump which is situated directly below the cabin. It mostly runs on takeoff and landing, but it can also run automatically at other times.
Dogs have been reported to need psychiatric treatment after being transported on a 787.
6$\begingroup$ If you could maybe provide a source for the last line there... $\endgroup$– Jay CarrOct 21, 2015 at 4:19
1$\begingroup$ @KorvinStarmast, I am thanking him for the reply and the description of the hydraulic pump. $\endgroup$ Nov 21, 2016 at 23:43
This isn't too unusual compared to other airliners eg A330, etc. The sound comes from the rotary hydraulic motor situated in the wheel well of the jet which turns the drive shaft for the flap drive screw jacks. This is a typical arrangement for Boeing jetliners.