What happened
On 16 November 2014, a Team Minimax 91, registration G-CGGX, was involved in an accident near Ruthin, Denblihshire, during a private flight. The pilot had recently reinstalled the Rotax 447 engine following an overhaul. During pre-departure power checks, the pilot observed that the maximum RPM was 5,800, which was lower than the expected 6,100 RPM. Despite this discrepancy, the pilot proceeded with the takeoff.
The aircraft accelerated more slowly than usual across the takeoff field. Shortly after reaching an altitude of approximately 60 feet, the engine suffered a total loss of power. While attempting a gentle right turn toward a suitable field for a forced landing, the aircraft's right wing stalled and dropped, causing the aircraft to enter an incipient spin. The pilot managed to reduce the steep nose-down attitude before the aircraft struck a grass surface. The impact resulted in severe damage to the engine mountings, landing gear, and the right side of the fuselage, but the pilot sustained only minor injuries.
The investigation
The investigation examined the engine's recent maintenance history and the flight dynamics leading to the impact. It was established that the engine had been sent to a specialist to investigate a power reduction, where a stuck piston ring was identified. Following the engine's return, the pilot noted that the engine was difficult to start and was not reaching normal RPM levels. The investigation also reviewed the pilot's actions during the engine failure and the subsequent maneuver that led to the spin.
Findings
- The engine was not producing its normal power output during the pre-flight check.
- The pilot elected to take off despite noticing the reduced maximum RPM.
- The total loss of engine power caused a significant drop in airspeed.
- The initiation of a turn during this low-speed state led to the wing stall and subsequent spin.