Originally Posted by
awair
This was a factor in the Kegworth 737 accident. So yes, it would be good to know.
- The ‘N1 equalisation function’ was not well-known by crew.
- The ‘bad’ engine was causing the good engine to fluctuate similarly.
- Shutting down the good engine (splitting the thrust levers) turned off the ‘feature’, resulting in a confirmation bias that the correct engine had been identified.
There were multiple other factors, but this definitely did not help.
As is often the case, we are unaware of what we need to know before the wake-up event.
Unless, as Mech Eng notes, there was another Kegworth accident, that aircraft didn't even have the auto sync 'trim' system which is only on FADEC engines (it was a 737-300, hydromechanical engine controls). The autothrottle simply tries to keep both engines at the desired N1, which shouldn't exactly be a surprise to the pilots since that's the function of the autothrottle. Without the trim, any change in commanded N1 requires thrust lever movement.