What happened
On an afternoon flight in Ontario, a privately owned Ryan Aeronautical Navion B, registration C-FTRM, departed Brantford for a breakfast fly-in. After a brief stop in Guelph to collect a passenger, the aircraft departed Runway 23. During the initial climb, the engine suffered a sudden loss of power. This failure caused the aircraft to stall and enter a spin. The aircraft struck the ground in a nose-down attitude, with the right wing making first contact, before cartwheeling 94 feet from the impact point. The two occupants sustained fatal injuries.
The investigation
Investigators examined the engine and components to determine the cause of the power loss. While the aircraft had been involved in a propeller ground strike in June 2004, testing of the reduction gearbox showed no evidence of sudden stoppage or damage from that event. Additionally, while the fuel selector valve showed internal leakage during testing, it was not determined to be a factor in this specific engine failure.
Technical analysis of the engine revealed that the crankshaft had fractured at the forward fillet radius of the number six connecting rod journal. The investigation also looked into maintenance records, noting that the propeller strike in 2004 was not documented in the aircraft's journey or technical logs, and that the aircraft had been flown several times following a propeller overhaul without a certified maintenance release.
Findings
- The primary cause of the engine failure was a fatigue crack in the crankshaft, which originated from corrosion pitting and was exacerbated by a lack of a case-hardened layer due to a manufacturing error.
- The pilot failed to maintain control of the aircraft following the power loss, leading to a decrease in airspeed below safe limits, which resulted in a stall and an unrecoverable spin.
- Maintenance discrepancies were identified, including the failure to record a prior propeller strike and the operation of the aircraft without a certified maintenance release following propeller installation.
- The investigation noted that current Canadian recency requirements may leave pilots unprepared for critical emergencies, as there is no requirement for periodic recurrent flight training or proficiency demonstrations for private pilots.