Beech S35 N322D accident near Deridder, Louisiana

Probable cause

A total loss of engine power due to oil starvation after the oil filler cap separated from the oil filler tube during flight due to corrosion. Contributing to the accident was the pilot's failure to maintain airspeed during low altitude operations, which precipitated the onset of a stall.

NTSB analysis

The pilot said that the airplane was in cruise flight at 5,500 feet mean sea level when he heard an "odd" sound coming from the engine. He diverted to the nearest airport but then saw oil on the windscreen and smoke in the cockpit. When he realized he would not reach the diversion airport, the pilot made a gear down landing in a field. Before touchdown, the pilot pushed the control column forward in an attempt to avoid a stall, and the airplane landed hard.

Examination of the engine revealed damage consistent with oil starvation. Examination of the engine assembly did not reveal any blocked or restricted oil ports/galleys or slipped/elongated bearings that would result in a loss of oil or oil pressure. Examination of the cap for the oil dipstick revealed it was severely corroded and the tangs used to secure it to the oil filler tube were missing. The cap for the oil gauge rod (dipstick) had separated from the dipstick and was found several feet away from the main wreckage; thus it is likely that the oil leaked out from this location.

Text from the NTSB. Open the NTSB docket for CEN13LA072 for the full record.