I can recollect two incidents over the years flying in the back
One was Branff 727 out of Kansas City where a window started to make a loud whistling noise - after inspection by the FO we dropped to 5000 ft approx and slogged into Chicago in one piece
Another was the door on an Aeroflot Tu-154 which also gave out some very strange noises - but we all just fastened our seat belts and resorted to the power of prayer