I also thought that even if the engine was damaged and slowing down, the position of the throttles would actually pump the same amount of fuel into the engine regardless.
Not unless there was actually a difference in power output between the A/T engaged and the manual one (disconnected) which the document was saying thus the noise going away but IT HAD TO BE A SUBSTANTIAL DIFFERENCE me thinks.
But then again, the engine has already been damaged. Would the EEC could have done this (reduce the fuel flow on the left engine)
I was thinking about what Capt Brush said but it was coincidental that the banging noise went away as soon as the rt engine was idled and they haven't even touched the left one as they had no reason to at that time before the descent.
Or maybe it was really a serious design flaw in the new engine or it's circuitry since they had to recall close to 100 aircrafts.