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.