Amateur-built Avid Mark IV N43280 accident near Hibbing, Minnesota

Probable cause

The improper installation of a hose clamp, which resulted in an oil line rupture and subsequent loss of engine oil pressure.

NTSB analysis

The pilot reported that during the local flight the engine lost oil pressure and the cockpit began to fill with smoke. He immediately reduced engine power to idle and performed a forced landing to a nearby field. The airplane collided with a barbed wire fence during the landing roll and subsequently nosed over. The fuselage, right wing, and vertical stabilizer were substantially damaged. A postaccident inspection revealed that the oil supply line to the oil cooler had ruptured, which allowed oil to come in contact with the engine's hot exhaust, producing smoke. The rubber, automobile-style oil line had failed immediately adjacent to its respective oil cooler inlet fitting. The hose clamp used to secure the oil line to the inlet fitting was not properly positioned over the fitting, which allowed the unsupported hose clamp to abrade through the oil line.

Text from the NTSB. Open the NTSB docket for CEN12CA035 for the full record.