What happened
On 6 August 2006, a Denney Kitfox Mk 3, registration G-BTMX, was conducting a short local flight near Wheaton Ashton, Staffordshire. A few minutes into the flight, the Rotax 582 engine stopped abruptly without any prior warning.
In response to the loss of power, the pilot attempted to select a suitable field for landing. During the initial approach, the passenger identified cables crossing the first intended field, prompting the pilot to select an alternative location further downwind. However, due to the low altitude of the aircraft, the pilot was unable to reach this second field. The aircraft instead struck a field containing a cereal crop approximately three to four feet high, roughly 80 meters short of the intended target. Upon impact, the aircraft slewed 180 degrees and decelerated sharply. Both the pilot and the passenger, who were wearing full harnesses, sustained spinal fractures and other injuries, requiring airlift to a hospital.
The investigation
The investigation focused on the cause of the engine failure and the circumstances leading to the unsuitable landing site. The engine was removed and stripped for examination. Investigators found that the big-end bearing on the front cylinder had failed. The engine had completed 325 hours on its current crankshaft assembly. While an inspection had been performed at 294 hours, the crankshaft assembly had not been replaced as recommended by the manufacturer.
Additionally, the investigation examined the pilot's decision-making regarding the landing site. It was noted that the pilot had not utilized the aircraft's flaps during the descent. While the pilot had avoided using flaps recently to maintain better aileron effectiveness, the lack of flap deployment meant the aircraft's glide range was not maximized, which could have been critical in reaching the second field.
Findings
- The engine failure was caused by a big-end bearing failure.
- The engine had exceeded the manufacturer's recommended 300-hour interval for crankshaft assembly replacement.
- The pilot's ability to reach the second field was compromised by the low cruising altitude and the late identification of cables in the primary landing site.
- The lack of flap deployment reduced the aircraft's gliding range during the forced landing.