@FiveGirlKit:
The auto-thrust computer will change from commanding climb thrust to looking at IAS when levelling off from a climb. The IAS will increase, so auto-thrust starts pulling the levers back. It does this via motors* which engage to the levers via clutches which are designed to slip above a certain torque.
One thrust lever jams with its engine at climb thrust but the auto-thrust does not know this, it only knows the IAS is still increasing, so it keeps driving the motors to pull both levers back. One lever is still stuck on climb thrust, so the auto-thrust keeps driving the motors to pull both levers back - but only one lever moves; the other lever is jammed and its clutch slips.
In this way you could end up with one engine at, say, 87% N1 and the other at say 35% N1 - a big split.
*Edit: Sorry, I originally claimed one motor for both levers, which is not the case. My bad.
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Last edited by Uplinker; 10th Feb 2021 at 14:30.