Piper PA-23-150 N3162P accident near Tucson, Arizona

Probable cause

The pilot’s failure to maintain airplane control during takeoff following the loss of left engine power due to the failure of the left engine-driven fuel pump’s diaphragm. Contributing to the accident was the pilot’s failure to use the electric fuel boost pumps for takeoff in accordance with checklist procedures and to conduct the engine failure emergency procedure.

NTSB analysis

The private pilot, who did not have a multiengine rating, reported that, during takeoff, the airplane's nose starting turning left; he did not realize that it was due to the left engine losing power. As a result, he did not perform the engine failure emergency procedure. A witness reported hearing one of the engines "misfiring" and subsequently seeing the airplane drift left, roll into a steep left bank, and then impact the ground.

Postaccident examination revealed no fuel in the left engine's fuel strainer and carburetor; the right engine's fuel strainer and carburetor both contained fuel. Fuel was present in both the left and right wing fuel tanks, and no evidence of fuel contamination was found. The left engine-driven fuel pump's diaphragm was found to be brittle and cracked in several locations, which resulted in its inability to provide sufficient fuel pressure to maintain engine power during takeoff. No other anomalies were found with the left engine's fuel system. The electric fuel boost pump switches were both found in the "off" position, indicating that the pilot had not turned them on before takeoff as called for in both the owner's handbook before takeoff checklist and the before takeoff checklist located on a placard on the instrument panel. If the pilot had turned on the electric fuel boost pumps, the left engine would not have lost power because the electric pump would have compensated for the malfunction of the engine-driven pump.

Text from the NTSB. Open the NTSB docket for WPR14LA027 for the full record.