Beech A36 N6677D accident near Poughkeepsie, New York

Probable cause

A leaking fuel discharge fitting, which resulted in a partial loss of engine power and an off-airport, gear-up landing.

NTSB analysis

The pilot landed the airplane at an intermediate airport to refuel before resuming his cross-country flight. After refueling and sumping the tanks, he taxied, performed an engine run-up, checked the magnetos, and cycled the propeller. During takeoff, the pilot noticed a vibration and unusual noise as the airplane rotated. He applied the brakes, as he thought the wheels were rotating and causing the vibration, and retracted the landing gear, but the vibration continued. The engine then lost partial power. He checked that the propeller, throttle, and mixture controls were full forward, but the airplane would not climb. He indicated that, due to the low airspeed, he could not return to the airport, so he pulled back on the control wheel to clear power lines, "forced the nose down" to prevent a stall, and landed gear-up, during which the airplane sustained substantial damage.

Examination of the wreckage revealed no evidence of preimpact failures or malfunctions of the airplane or engine. Fuel was observed in both the left and right wing tanks.

A postaccident engine test run was performed in a test cell. The engine started normally; accelerated normally without any hesitation, stumbling, or interruption in power; and produced rated horsepower. Testing of the auxiliary fuel pump, which was designed so that fuel would flow through it regardless of whether it was on or off, revealed that although it was operating within specifications, the discharge fitting was leaking, which allowed air into the fuel system. Disassembly of the discharge fitting revealed that it had likely been installed to the proper torque but that there were deep scratches on the O-ring boss on the pump side of the fitting and a piece of metal embedded in the O-ring, which indicates that it had been damaged before or during installation. After the fittings were replaced, no leaks were found.

Text from the NTSB. Open the NTSB docket for ERA15LA286 for the full record.