I am using the CH Throttle Quadrant. Since PB 9 I have the problem, that the the thrust jumps back to idle during the flight. This appears in all aircrafts. I calibrated the throttle quadrant several times.

Any ideas?

This may help diagnose the problem: Go into the Settings menu, choose Data Output, and enable the first check boxes for the two items below (Show in Cockpit):

Throttle (commanded)
Throttle (actual)

That puts a constant readout of the values on your monitor, and you can track what's happening during the flight. If the Throttle (commanded) value drops out, it could be a problem in the throttle quadrant, like maybe dirt in the encoder. If the Throttle (commanded) value stays the same and the Throttle (actual) value drops, then it would indicate something in the sim, like running out of fuel or an engine overheat that's independent of the CH throttle input.