Accident Sequence
The airplane was destroyed when it impacted terrain during takeoff climb from runway 18. The wreckage was located in a harvested cornfield about 600 feet east of runway 18. The wreckage path was approximately 65 feet long on a heading of about 030 degrees magnetic. A propeller slash was unearthed about 30 feet from the initial point of impact; the slash was about 51 inches long at ground level and about 18 inches deep. The north side of the slash had been polished smooth and exhibited a gray color similar to the paint on the propeller blades.
Witness Accounts
Witnesses reported seeing the airplane bank left after raising its landing gear about 100-150 feet above ground level. One witness heard a momentary engine overspeed after the gear were raised. Another witness observed the airplane in a steep bank of approximately 80 degrees, which then reduced to about 30 degrees prior to impact.
Passenger Report
The passenger in the right rear seat reported that during takeoff the engine started "missing." The pilot stated, "This isn't right," reached to adjust something, and soon after the engine smoothed out. The pilot made a radio call (inaudible to the passenger) and banked the airplane left. The passenger reported that the nose and left wing dropped, and the left wing impacted the ground with about a 30-degree angle of bank. The nose hit the ground, the airplane spun around, but did not cartwheel, before stopping. The passenger believed the engine was operating normally at impact.
Wreckage Examination
Flight control continuity was confirmed between all controls and their respective surfaces. The engine rotated and had thumb compression and suction on all cylinders. The propeller blades had rotational scoring of paint on the camber side but no twisting or deformation of the tips.
Propeller Governor Findings
The propeller governor's pressure relief valve spring was found broken due to a fatigue fracture. A functional test revealed that the pressure relief setting and pump capacity were well below specified minimums. Hartzell Propellers reported, "Such deficiency might cause a propeller to operate at reduced blade angle and higher than normal RPM after takeoff." Replacement of the pressure relief valve spring at overhaul was required by Service Bulletin 176 dated November 15, 1991, but that replacement was not performed.
Terrain
The terrain south of runway 18 was an open field with few obstacles.