Piper PA34 N41382 accident near Groton, Connecticut

Probable cause

The reported partial loss of right engine power for reasons that could not be determined based on available evidence.

NTSB analysis

During an instructional flight, the pilot receiving instruction performed several landings at several airports before proceeding to the home base airport where he executed two touch-and go landings and remained in the airport traffic pattern. When abeam the approach end of the landing runway while on the downwind leg of the airport traffic pattern with the landing gear extended and 10° of flaps extended, the receiving instruction began to descend while turning onto the base leg of the airport traffic pattern. The flight instructor stated that at time he heard an engine sputter and verified the engine controls were in the proper position. He heard the engine sputter again and "felt the [airplane] jerk" and stated, "my controls." He maintained airspeed and verified the engine controls were full forward, retracted the flaps but decided to leave the landing gear extended due to the altitude and proximity to the airport. He verified the malfunction to be the right engine and felt it was developing some power, but with less output than the left. He briefly pitched nose down, then nose up, and when he noticed a high descent rate, he feathered the right propeller and placed the right mixture control to idle cutoff. He maneuvered for a forced landing on a street but collided with and remained suspended in the roof of a house.

Postaccident examination of both engines, their systems, left propeller, and left propeller governor revealed no evidence of preimpact failure or malfunction. There was no evidence or preimpact failure or malfunction of either fuel supply system.

While the flight instructor reported he moved the right propeller control to the feather position near the end of the flight, the right propeller blades were on the start locks and not feathered. Functional testing of the right propeller and operational testing of the right propeller governor revealed no preimpact failure or malfunction. Therefore, there was no mechanical reason why the right propeller blades would not feather if commanded before the engine rpm became too low and engaged the propeller start locks.

Text from the NTSB. Open the NTSB docket for ERA20LA287 for the full record.