NTSB Factual Report

HISTORY OF FLIGHT

On September 4, 1996, at 1830 central daylight time, an experimental Green Castle Aero Club, Ltd. aerobat, N95GC, operated by the Green Castle Aero Club, Ltd., was destroyed when it impacted terrain following an in-flight loss of control in Oxford, Iowa. The commercial rated pilot sustained fatal injury and the pilot rated passenger sustained serious injury. The local, 14 CFR Part 91, instructional flight originated about 1830. Visual meteorological conditions prevailed and no flight plan was filed.

A witness to the accident, a local farmer, reported that he observed the airplane "banking into a turn, low to the ground, with its tail very low." He stated he did not actually see the accident but "saw the dust and knew there was a crash." He stated he did not hear anything because he was "too far away" and he is "hard of hearing."

During a personal interview, conducted by a detective from the Johnson Count Sheriff's office, the pilot rated passenger reported they "were having trouble gaining enough airspeed and barely cleared the trees after takeoff." He reported the other pilot assumed control of the airplane. They "continued having trouble getting the proper amount of airspeed." The next thing he remembered was "the ground coming at them." The pilot rated passenger reported that he did "not recall hearing the engine miss."

WRECKAGE AND IMPACT INFORMATION

The NTSB on-scene investigation began September 5, 1996, about 0730. The wreckage was located in a corn field approximately 1/2 mile south of the Green Castle Airport. Gently rising terrain led from the airport to the accident site. The wreckage path was on a heading of 225 degrees and was located on a slight uphill grade. The first item in the wreckage path was a propeller blade. The corn stalks were sliced for about 20 feet, at a descending angle of approximately 25 degrees, leading to a shallow impact crater. The corn immediately surrounding the accident site was undamaged.

The right wing was crushed aft at a 30 degree angle starting at a point approximately four feet outboard of the root. The left wing tip was slightly damaged and the fabric was wrinkled. Both wings were folded in the aft direction. The both flaperons were separated at the hinges and the left flaperon was fractured three feet from the root. The forward fuselage was fractured below the seat and exhibited substantial crushing. The fuselage and empennage were relatively intact aft of the cabin. The left landing gear was bent forward and the right landing gear was bent aft. The left side of the cowling remained attached to the fuselage and the right side was displaced. All three blades of the composite propeller were fractured near the root and the main shaft of the reduction drive unit was bent.

Examination of flight control continuity revealed the left rudder cable was fractured on the left side of the cabin. No other evidence of preimpact flight control or engine control malfunction was discovered. Microscopic examination of the fractured rudder cable at the NTSB laboratory revealed "ductile overstress separation."

Examination of the engine revealed the forward right automotive type spark plug leads was disconnected from the spark plug. The lead exhibited minor impact damage and abrasion. The spark plugs were in new condition. The number two spark plug was slightly more sooted than the other three. The ignition coil also exhibited minor impact damage.

The reduction drive was removed and the engine was installed in a test stand with a conventional propeller. The engine fired intermittently but would not start when hand propped. The ignition coil and distributor were replaced with a conventional mechanical distributor. The engine started and operated normally. The distributor, ignition coil, and spark plug leads operated normally when tested on an automotive distributor test stand.

MEDICAL AND PATHOLOGICAL INFORMATION

The autopsy of the pilot was conducted at the University Hospital, Iowa City, Iowa, on .

Federal Aviation Administration Toxicological testing of the pilot was negative for all tests conducted.

ADDITIONAL DATA/INFORMATION

Parties to the investigation were the Federal Aviation Administration Flight Standards District Office, Des Moines, Iowa, and the Green Castle Aero Club. Following the on-scene investigation the main wreckage was released to a representative of the Green Castle Aero Club. The distributor assembly, ignition coil, ignition leads, and left rudder cable were subsequently returned to the Green Castle Aero Club.

NTSB Probable Cause

failure of the private pilot to maintain sufficient airspeed after takeoff, during the initial climb and turn to the crosswind leg; and a delay by the flight instructor (CFI) in taking remedial action to avoid a stall.