What happened
During the takeoff roll of the aircraft type, the pilot achieved a positive rate of climb. However, once the airspeed reached 110 knots, the landing gear had been retracted, and the flaps were set to 10 degrees, the pilot observed a right roll and a decrease in climb performance. Specifically, the manifold pressure on the right engine dropped to approximately 34 inches, while the left engine remained at 42 inches.
Faced with a minimal climb rate, increasing terrain ahead, and stagnant airspeed, the pilot elected to perform an emergency landing in a small field located roughly 0.25 miles from the runway at a 50-degree angle to the left. To increase airspeed, the pilot aggressively lowered the nose and extended the flaps. The aircraft subsequently landed in a nose-high attitude with the landing gear only partially extended.
Post-accident inspections of the airframe showed vertical compression on the belly, a split in the fuselage at the rear of the cabin, and damage to both wings, including a downward buckle on the left wing. The aircraft was also found to be approximately 74 pounds over its maximum takeoff weight of 6,200 pounds.
Findings
Investigation of the right engine intake manifold revealed that a clamp was loose, which contributed to the power loss. Calculations from the type certificate holder indicated that even with a partial power loss, the aircraft should have maintained a climb rate of 830 fpm under the specific configuration used. The pilot, who possessed 15,000 total flight hours, was operating in an area where terrain elevation increased to the east, necessitating the decision to land to the west.