What happened
On July 12, 2008, a Grumman G-164A, registration N7395, crashed in a wooded area near Pelham, Georgia, during an aerial application flight. The aircraft was operating under 14 CFR Part 137 in visual meteorological conditions.
Witnesses reported hearing the engine making "popping" noises and sounding like a helicopter as the aircraft flew past. One observer noted the airplane circled a pond twice before descending into the terrain. The aircraft struck a small grassy clearing, nosed over, and collided with shrubs and trees, resulting in a post-impact fire. The pilot sustained 1 fatal injury.
The investigation
Investigators examined the engine, which had undergone significant maintenance approximately two weeks prior to the accident. During that maintenance, a mechanic had discovered fragments of piston rings, a piston skirt, and a broken governor drive gear inside the engine case. The engine was cleaned and reassembled, and the aircraft was test-flown successfully.
Post-crash examination of the engine revealed several findings:
- Internal damage was consistent with the engine operating with loose metallic items inside the case.
- Multiple piston ring fragments were recovered from the engine case.
- Three gear teeth from the collector intermediate gear were found loose in the accessory section; the fracture patterns were consistent with a sudden engine stoppage.
- The number two, four, and eight pistons showed impact marks from metal fragments on their undersides.
- The investigation could not determine if the recovered ring fragments were remnants of previous issues or parts of the rings installed during the recent maintenance.
An autopsy of the pilot revealed severe coronary artery disease and an enlarged heart, though the investigation found no evidence that medical impairment or incapacitation contributed to the crash.