LAX95LA290

The pilot was practicing touch-and-go landings and takeoffs. A ground witness reported that on the last takeoff an engine began to backfire. The airplane began to descend, while the backfiring continue, and disappeared from the witness' view. Another pilot, practicing touch-and-go landings and takeoffs, observed the airplane lying northeast of the runway departure end. Examination of both engines disclosed no evidence of any internal preexisting malfunctions or failures. The right engine magnetos timing exceeded the manufacturers' service limits. According to an accessory repair technician, neither magneto is considered airworthy.

On August 12, 1995, about 0715 hours mountain standard time, a Piper PA-30-30, N8113Y, crashed on the departure end of runway 05 at Wickenberg Municipal Airport, Wickenberg, Arizona. The pilot was conducting a visual flight rules personal flight. The airplane, registered to and operated by the pilot, sustained substantial damage. The certificated airline transport pilot, the sole occupant, sustained serious injuries. Visual meteorological conditions prevailed. The flight departed Falcon Field, Mesa, Arizona, at an undetermined time.

A local flight instructor reported that he and his student were practicing touch-and-go takeoffs and landings on runway 05. The accident airplane entered the traffic pattern and began executing touch-and-go takeoffs and landings.

On the third takeoff, the accident airplane's pilot announced over the common traffic advisory frequency that he was going to depart the pattern to the east. The CFI's student landed the airplane and then departed. On the initial climb out, the CFI observed that N8113Y crashed to the right of the departure end of the runway. Neither the CFI nor his student observed the accident.

A ground witness told the investigating Wickenberg Police Officer that she was sitting in front of the airport office at the time of the accident. She said that she saw the airplane execute two touch-and-go landings and takeoffs. The witness said that on the last takeoff she heard two distinctive engine backfires. The airplane began to descend and then she heard two louder backfires. The airplane descended out of her view.

An inspector from the Federal Aviation Administration (FAA), Phoenix Certificate Management Office, conducted the on-scene investigation. He reported that the airplane came to rest, right-side-up, about 60 feet east of the taxiway facing in a northeasterly direction. He said the airplane and its flight control surfaces were intact.

Both engines' propeller blades were found in the feathered position. The propeller blades displayed leading edge gouging and chordwise scuff marks.

Both engines were examined at Air Transport, Phoenix, Arizona, on August 17, 1995. A representative from Textron Lycoming, an accredited party to the investigation, participated in the examination.

Continuity of both engines' gear and valve train assemblies was established. The differential compression was found within serviceable limits.

Fuel was found in both engines' fuel system and their respective engine driven fuel pumps operated normally.

The engines' oil suction screen and filter were free of contaminates.

Both engines' magnetos timing were off between 2 and 3 degrees. The right engine magnetos were tested and disassembled at an accessory repair facility on August 17, 1995. The magnetos produced spark when operated on the test bench.

The right magneto impulse coupling was inoperative. When loosened, the impulse coupling (pawls) operated normally. The pawls' rivets were loose on the cam. The left magneto rotor was between 0.008 and 0.010 inches loose.

The technician said that he did not consider either magneto airworthy.

The pilot did not submit the required aircraft accident report. His wife told National Transportation Safety Board investigators that he does not remember any of the events preceding the accident.

Safety Board investigators did not obtain the pilot's personal flight hours logbook. The flight time data reflected on page 3 of this report were obtained from the pilot's insurance representative.

The airplane data reflected in this report were obtained from the airplane's maintenance logbooks.