What happened
On a morning flight near Kamloops, British and Columbia, a pilot operating an amateur-built Stits Playmate, registration C-FWFU, experienced a sudden loss of engine power. After flying north of the Kamloops airfield, the pilot transmitted a weak radio call to the Flight Service Station, reporting engine issues and an intention to perform a forced landing.
Witnesses observed the aircraft flying low and parallel to Highway 5 with a rough-running engine. During the descent, the aircraft's wings began to wobble, the left wing dropped, and the plane entered an abrupt left turn. The aircraft struck a telephone line and impacted an embankment below the highway level. The pilot sustained fatal injuries in the crash.
The investigation
The investigation focused on the engine's performance and the environmental conditions at the time of the accident. Investigators examined the Lycoming O-320-B1A engine and found that the aircraft was being operated using red-dyed automotive gasoline (MOGAS) rather than standard aviation gasoline.
Technical inspections of the engine components revealed that the left magneto was malfunctioning, failing to operate all spark plugs at lower RPMs. While the carburettor and magnetos had defects that could cause rough running, investigators determined these alone were insufficient to cause the total loss of power observed. The investigation also noted that the pilot was not wearing the available shoulder harness, which increased the severity of the injuries.
Findings
- Carburettor icing was identified as the primary factor leading to the loss of engine power.
- The atmospheric conditions, specifically the combination of temperature and dew point, were highly conducive to serious ice formation in the carburettor.
- The use of automotive gasoline increased the susceptibility of the engine to such icing.
- The aircraft entered an aerodynamic stall at an altitude too low to allow for recovery.
- The lack of use of the shoulder harness contributed to the fatal outcome.