A PA46 pilot and instructor experienced a power loss on final approach. While trouble shooting and prior to engine shut down; the engine returned to normal and a normal landing ensued.
Synopsis
A PA46 pilot and instructor experienced a power loss on final approach. While trouble shooting and prior to engine shut down; the engine returned to normal and a normal landing ensued.
Narrative
Normal takeoff with 20 KT headwind and performed two circuits around the traffic pattern to a full stop and taxi back. On the third approach to landing after turning final on approximately 3/4 mile final; the torque indication rolled back and the airplane began to decelerate; the prop felt as it was going towards the flat position. The throttle linkage became totally ineffective in any position. Immediately I instructed the flying pilot to set up and maintain best glide speed; 105 KTS. I retracted the landing gear and approach flaps; checked for ignition and fuel pumps on. Confirmed with the flying pilot the failure and to wait on condition lever/feather. Next step was to activate the emergency throttle over ride. Just before this action was to take place the torque began to increase and the engine came back on line. A normal descent to the runway and routine landing to a full stop followed. The loss of power was approximately for 30-45 seconds. The cause of the power loss is unknown and under investigation. The CRM between the flying pilot and the non flying pilot plus knowledge of the aircraft and systems contributed to the safe outcome in this emergency situation..
Second reporter narrative
[It was a] normal takeoff with ten degrees of flaps into a headwind of 20 KTS. I was flying a left closed pattern. When I turned base leg I added ten degrees of flaps and then the instructor reminded me that we were going to do this final landing with no beta and no flaps. I said 'no problem' I will raise the flaps and add power. I raised the flaps and went to move the throttle forward and noted no response. I watched the torque drop to zero from the 500 or so it had been. I tried the throttle twice again; full range; and informed the instructor that I had no response. I set to flying the plane and he looked to see if there were any switches or items that were not in a normal position for landing. I raised the gear to reduce drag and discussed a desire to wait on feathering until I had tried the manual override. The instructor agreed. I then reached down to engage the override but decided to try the throttle one more time. It was now in the full aft position; power returned with normal movement. We then set up for a normal landing. I would say that the loss of power lasted about thirty seconds. The cause is under investigation. Pilot and instructor worked calmly to reconcile the problem and this helped reduce stress and added to the positive outcome.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.