NTSB Identification: LAX07LA004.
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Accident occurred Sunday, October 08, 2006 in Oakdale, CA
Probable Cause Approval Date: 11/29/2007
Aircraft: Grumman American AA-5B, registration: N39ER
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

Upon experiencing a total loss of engine power during cruise flight, the pilot made a forced landing during which the airplane overran the runway's departure end and impacted a fence. The pilot reported that during the flight she "heard an abnormal noise coming from the engine - a loud knocking sound. Within just a few seconds, the engine exploded and a rush of oil from the engine compartment flooded the wind screen, obscuring about 90 percent of the forward field of view....The cabin started to fill with smoke from burnt oil," and the propeller stopped rotating. The pilot force landed on a 2,000-foot-long airstrip. Upon exiting the airplane the pilot observed that the top portion of the engine's case was punctured. The pilot had purchased the 1978 model airplane earlier during 2006, and she had possession of its maintenance records. The records indicated that the engine received three (field) overhauls in 1980, 1991, and in 1994. By the accident date, the engine's total time and time since last overhaul was 5,538 and 950 hours, respectively. Examination of the engine found that it had sustained an internal catastrophic mechanical failure, which resulted in a breach of the crankcase at the forward top section. The oil lines were found secure at their respective engine fittings, the crankshaft and respective connecting rods exhibited severe heat distress consistent with lubrication deprivation. The number 1, 2 and 4 connecting rods were displaced from their respective journals. The number 3 connecting rod remained on the journal, which exhibited severe heat distress. The crankshaft and camshaft remained intact. No anomalies were found with the accessory components and gears, or with the lubricating system. The specific event leading to the lubrication deprivation and heat distress was not identified.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A total loss of engine power resulting from lubrication deprivation for undetermined reasons.

Full narrative available

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