NTSB Factual Report

On August 10, 1995, at about 1000 eastern daylight time, a Challenger II homebuilt airplane, N890JH, operated by the student pilot/owner/builder, descended into terrain near Madisonville, Kentucky. The student pilot, the sole occupant, was fatally injured, and the homebuilt airplane was destroyed. Visual meteorological conditions prevailed and a flight plan was not filed. The personal flight was conducted under 14 CFR 91. The flight originated from Nortonville, Kentucky, exact time unknown. The intended destination was Greenville, Kentucky.

According to a Federal Aviation Administration (FAA) Air Safety Inspector, a witness reported that he saw the airplane operating at about 100 feet above the trees, and the engine sounds were intermittent. A second witness stated that he noticed the airplane flying at about 1000 feet above the ground when it made an abrupt "...nose dive." He stated that the engine was running. A third witness stated that he saw an airplane spiralling towards the ground at a steep angle. A search was initiated, and the wreckage was located later that afternoon. The wreckage was removed to a hangar at a nearby airport for postaccident examination.

The FAA Inspector reported that during the postaccident examination, he established that control cable continuity to the flight controls existed prior to impact. He stated that the engine rotated, the spark plugs looked normal, and there was fuel present in the carburetor. The FAA Inspector noted that the student pilot/owner/builder had recently converted the engine to a dual ignition/spark plug system. The accident flight was the first flight since the conversion.

The FAA Inspector stated that the student pilot/owner/builder's conversion was "...not totally [in accordance with]..." the manufacturer's recommendations, and that the workmanship was of poor quality. He stated that when the flywheel housing was removed to reveal the internal components of the ignition system, he observed that the wires going to the magnetic pickups had been "...pinched..." between the housing and the crankcase mounting surface and the wire insulation was broken. He stated that the wires were "...shorting out." According to the Manufacturer's recommendation, the student pilot/owner/builder should have filed a bevel into the edge of the housing which would have precluded the pinching of the wires. The FAA Inspector also stated that the student pilot/owner/builder had not drilled and tapped the mounting flange to so that the pick up plate could be secured with a screw after the timing was set.

According to the student pilot's relatives, he had not flown the accident aircraft in the preceding two years. They indicated that he was repositioning the airplane at another airport when the accident occurred. FAA records indicate that the student pilot had less than 30 hours total flight time.

Toxicological examination of the pilot detected 0.026 mg/100 ml ethanol in blood; however vitreous fluid tested negative for ethanol. The toxicological report contained the remark: "Apparent putrification."

NTSB Probable Cause

an intermittent short of the ignition system, due to improper maintenance/modification of the engine, which resulted in partial loss of engine power; and failure of the pilot to maintain adequate airspeed, which resulted in an inadvertent stall and collision with the ground. A factor relating to the accident was: the pilot's lack of recent flight experience.