Post take -off noise
 

I have flown quite a bit on B 777 and notice into the climb two or three instances of a short whining noise. I know nothing about aircraft mechanics and assumed it might be flap retraction. I have not noticed it on B747 or B737 300/700. Am I right about the reason for the noise and is there something particular with the B777? I should be grateful for advice from pro pilots/ engineers. Many thanks.

It is probably just the First Officer!:}

Seriously, yes, probably the hydraulics and associated hardware as the various stages of flap are wound in.

If you do not hear it during the approach to land also, it is as parabellum says, just the F/O..

Great response, needed a good laugh!

Thanks Chaps- and hilarious:)