What happened
On 9 March 2005, a Cessna 150J, registration ZS-FNN, was conducting a training flight departing from Virginia Aerodrome. The flight, which included an instructor and a student pilot, was intended to practice simulated forced landing procedures. After climbing to 2,500 feet above mean sea level, the crew began a descent, periodically applying carburettor heat to mimic engine failure conditions.
As the crew attempted to execute a go-around from a selected field at roughly 300 feet above ground level, the engine failed to respond correctly. Approximately 5 to 10 seconds after the pilot applied full power, the engine began running roughly and lost sufficient power to prevent level flight. The crew subsequently identified a dirt farm road for an emergency landing.
During the landing roll on the farm road, the aircraft struck a ditch, causing it to bounce. The aircraft then impacted the ground in a nose-down position, which resulted in the nose wheel assembly bending and the aircraft nosing over into a semi-inverted, tail-high position.
The investigation
The investigation focused on the engine's failure to produce power during the go-around attempt and the subsequent impact dynamics. Investigators reviewed the aircraft's maintenance history, noting that the most recent Mandatory Periodic Inspection had been completed on 25 February 2005, with 28 flight hours accumulated since that service.
Findings
- The primary cause of the inability to maintain flight was a sticky exhaust valve on the number one cylinder, which prevented the engine from reaching full power during the go-around.
- The engine was operating with the carburettor heat off at the time full power was applied.
- The aircraft's final position and the damage to the nose gear were caused by the aircraft entering a ditch during the landing roll, leading to a bounce and a subsequent nose-over.