Originally Posted by
Connedrod
Also if these estimates are correct for higher rpm you can forget about the power lever roll back.
Not necessarily. Quote below from the Blackbushe accident.
Power lever migration
Tests were carried out, both on the ground and in flight, to examine power lever migration with the friction selected fully off. Take-off power of 2,230 ft lbs was set and 2,000 propeller rpm (governed) was selected. When the pilot removed his right hand from both power levers on the ground, they migrated aft initially very quickly to 1,000 ft lbs and then more slowly with the torque falling to 400 ft lbs. The left propeller lever moved more rapidly aft on each occasion and on different test aircraft. This was possibly due to the fact that the control cable to the left engine is shorter and subject to less friction than the cable controlling right engine.
On the ground when the power lever moved the propeller rpm reduced immediately to 1,900 rpm but then fell further to 1,600 rpm. In flight the left propeller rpm reduced to 1,800 rpm with the IAS at 110 kt representative of the speed at which the accident aircraft rotated from the runway and the speed at which the propeller rpm was seen to initially decay.
Hypothetically speaking, a "higher" RPM could have come about from realising what the problem was, and the lever pushed forward again but by then it was too late to recover.
This was possible in the Blackbushe accident, with final derived prop speed about 2125rpm.