On 21 Oct 2011, a Houts Avid Mark IV was involved in an aviation accident near Hibbing, MN. No fatalities were reported. Investigators recorded the probable cause as: The hose-clamp used to secure the oil supply line to the oil cooler inlet fitting was not properly positioned over the fitting, which allowed the unsupported hose-clamp to abrade through the oil line, causing a rupture and subsequent oil leak. This summary draws on records from NTSB.
During a local flight, the pilot experienced loss of oil pressure and cockpit smoke. After a forced landing, the airplane struck a fence and nosed over. Inspection revealed a ruptured rubber oil line due to improperly positioned hose clamp.
Incident Summary
During a local flight, the pilot reported that the engine experienced a loss of oil pressure and the cockpit began to fill with smoke. In response, he immediately reduced engine power to idle and executed a forced landing to a nearby field. During the landing rollout, the airplane collided with a barbed-wire fence and subsequently nosed over.
Damage
The accident resulted in substantial damage to the fuselage, right wing, and vertical stabilizer.
Postaccident Inspection
A postaccident inspection revealed that the oil supply line to the oil cooler had ruptured. The rupture allowed oil to come into contact with the engine's hot exhaust, producing the smoke observed in the cockpit. The oil line was a rubber, automobile-style hose. The failure occurred immediately adjacent to the oil cooler inlet fitting. Investigators determined that the hose clamp used to secure the oil line to the inlet fitting was not properly positioned over the fitting. This mispositioning allowed the unsupported hose clamp to abrade through the oil line, leading to the rupture.
Probable cause
The hose-clamp used to secure the oil supply line to the oil cooler inlet fitting was not properly positioned over the fitting, which allowed the unsupported hose-clamp to abrade through the oil line, causing a rupture and subsequent oil leak.
Contributing factors
Causes
Incorrect service/maintenanceRecip eng oil sys — FailureMaintenance personnel