Accident Summary
The pilot reported that after takeoff, the airplane yawed to the left and the torquemeter for the left engine was fluctuating. The pilot feathered the left engine and began a turn back toward the airport.
Flight Details
The pilot maintained 20 degrees of flaps during the return. According to the manufacturer's directions, climb performance is not guaranteed if the flap setting exceeds 5 degrees. The pilot's airspeed was 115 knots; the manufacturer's directions specified a minimum of 140 knots. As a result, the airplane would not climb above 200 feet AGL.
Landing and Collapse
The pilot elected to land on the departure runway in the opposite direction. He approached the runway at a 90-degree angle and performed a 90-degree turn to align with the runway. He delayed landing gear extension to reach the runway. When the gear was extended, the airplane stalled and touched down before the gear reached the down-and-locked position. Subsequently, the landing gear collapsed and the airplane slid off the runway.
Post-Accident
The owner did not make the engine available for further testing after the accident.