Originally Posted by
Uplinker
I am probably being dim, but just wondering why the autosync refinement needed to be known by pilots?
Do you mean so as to ensure the autosync was engaged during flight to increase passenger, (and pilot) comfort? Or in case it ever went wrong?
In engineering, we call that the 'limited authority trim' - but yes, the autothrottle system sends a trim signal to each engine to match up N1 or EPR across the wing. It has a very limited authority (I don't recall the limits for EPR, but for N1 it's +/- 2.5% at lower altitudes and +/- 5% at cruise). While it's there on the 777 and 787, it's not really needed as there is a separate servo for each thrust lever that can (and will) simply move the lever slightly to get the same effect. However on the 747 and 767, there is a single servo that controls all the thrust levers so it does not have the ability to move an individual lever to match N1/EPR across the wing - hence the need for the trimmer.
Not sure why Discorde thinks the pilot specifically needs to know the workings of the trimmer system - dual servo autothrottle systems (new 737NG and MAX, 777, and 787) can perform the very same thing by simply making subtle adjustments to the lever position.
There is already a procedure that basically says if you don't like what the autothrottle is doing, simply turn it off - which also disables the trimmer system.