TQ runaway...
Experienced something similar on a B200 - I was unable to reduce TQ. It turned out to be caused by paint residue having entered the FCU actuating arm ball bearing...
Anyway, I also thought that shutting it down with the CL was the way forward, so to speak - and imagine my surprise when nothing happened upon closing the CL. Turned out the fuel pressure being generated by the EDFP was so high that the CL didn't have authority enough to close the valve.
Oh well, the good ol' fireswitch did the trick in the end, but still
at the time.
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