ATL96LA128

While climbing through about 2,500 feet after takeoff, the engine lost power. The pilot was forced to land on unsuitable terrain, which resulted in a collision with a tree. After the accident, the engine's left magneto was found jammed due to a failed impulse coupling. The jammed magneto broke the idler gear and the crankshaft gear with which it meshed, precipitating a total loss of power. The impulse coupling was the subject of an airworthiness directive that required recurring inspections at each 500 hours of engine operation. Records showed that the last inspection of the magneto was in November 1988, 432 hours after the engine had been overhauled. The last annual inspection was in October 1995, with a tachometer time of 2,905 hours since overhaul. At the time of the accident, the engine had a total flight time of 3,109 hours recorded since overhaul.

On September 19, 1996, about 1800 eastern daylight time, a Piper PA-32-300, N9VM, collided with trees and the ground during an emergency descent and forced landing at Georgetown, South Carolina. The airplane was operated by the owner/pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the personal flight. The commercial pilot received minor injuries, and the airplane was substantially damaged. The flight was originating at the time of the accident, and was destined for Savannah, GA.

According to the pilot, about 2,500 feet, during the climb after takeoff, he heard a "whoosh," and noted that the engine oil pressure indicated zero. Subsequently, the engine lost power, with the propeller continuing to windmill. During the attempted forced landing, the airplane collided with trees and the ground.

A Federal Aviation Administration airworthiness inspector, examined the engine on September 20, 1996. He reported that he discovered the left magneto was jammed. Further, the impulse coupling had failed and the left magneto would not rotate, after removal from the engine. The crankshaft gear did not rotate with the crankshaft. The crankshaft gear bolt was bent and had backed out enough to break the safety tab, and the dowel pin that aligns the gear to the crankshaft was sheared. Several teeth were broken from the left idler gear. Entries in the engine log indicated that the last recorded inspection of the magneto that is required by Airworthiness Directive (AD) 78-09-07R3 was November 2, 1988, which was 432.3 hours since engine overhaul. The AD specified recurring inspections of the magneto impulse coupling for wear each 500 hours of engine time in service. The AD was superseded by AD 96-12-07, however, the recurring inspection was still applicable.