What happened
During the takeoff climb from runway 18, a Cessna (type not specified in source) impacted the terrain. Witnesses observed the aircraft banking left approximately 100 to 150 feet above ground level after the landing gear had been raised. One observer noted an engine overspeed that appeared momentary following the gear retraction. Another witness reported seeing the aircraft enter a steep bank of approximately 80 degrees, which subsequently reduced to about 30 degrees before the impact.
A passenger seated in the right rear seat reported that the engine began missing during takeoff. The pilot reportedly remarked, "This isn't right," and attempted an adjustment, after which the engine performance stabilized. Following a radio call, the aircraft banked left; the nose and left wing dropped, and the left wing struck the ground at a 30-degree bank angle. The aircraft's nose hit the ground and the plane spun before coming to a rest. The wreckage was located in a harvested cornfield approximately 600 feet east of runway 18, with a wreckage path spanning about 65 feet.
The investigation
Investigators examined the engine and flight controls, finding continuity between all controls and their respective surfaces. The engine was found to be rotating with proper compression and suction on all cylinders. While the propeller blades showed rotational scoring of the paint, there was no evidence of twisting or deformation at the tips. A propeller slash was discovered 30 feet from the initial impact point.
Findings
An inspection of the propeller governor revealed that the pressure relief valve spring had failed due to a fatigue fracture. Functional testing showed that both the pressure relief setting and the pump capacity were well below the required minimums. According to Hartzell Propellers, this deficiency could cause the propeller to operate at a reduced blade angle and higher than normal RPM following takeoff. Additionally, it was noted that the replacement of the pressure relief valve spring during overhaul, as required by Service Bulletin 176 dated November 15, 1991, had not been performed.