On October 13, 1995, a Mooney M20K (registration N3983H) was involved in an aviation accident near Dalton, GA. Investigators recorded the probable cause as: Oil starvation for an unknown reason, which resulted in progressive connecting rod failure and subsequent loss of engine power. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a climb, the pilot experienced a drop in manifold and oil pressure, declared an emergency, and attempted an instrument landing at dusk. The aircraft impacted terrain. Investigation revealed failed connecting rods due to thermal stretching and broken bolts.
Incident Summary
The pilot reported that during a climb through about 7,000 feet above mean sea level, the engine manifold pressure decreased to approximately 22 inches of mercury, and the engine oil pressure dropped to zero. The pilot promptly alerted air traffic control that an emergency landing would be necessary. Subsequently, the pilot initiated an emergency instrument landing procedure at dusk. However, the pilot was unable to reach the intended runway, and the airplane impacted the terrain.
Post-Accident Findings
Examination of the aircraft revealed the presence of old oil stains on the underside, originating from the engine cowling and extending to the tail section. No evidence of a fresh oil leak was discovered, suggesting that the engine was not leaking oil at the moment of the accident. The engine was disassembled and inspected, revealing that the number one and number two connecting rods had failed due to thermal stretching and consequent breaking of the rod bolts.