What happened
On 26 June 2018, a Beech A36 Bonanza, registration G-CDJV, was performing a private flight departing from Benwick Airstrip in Cambridgeshire. Shortly after applying takeoff power, the single engine began misfiring, though the engine appeared to run more smoothly when the pilot reduced power. Recognizing the abnormal engine performance, the pilot decided to abort the departure and return to the airfield.
While on the left base leg of the approach, the misfiring intensified. The pilot attempted to rectify the issue by switching the fuel feed from the left tank to the right tank, but this action failed to resolve the engine's instability. As the engine was no longer producing enough power to maintain altitude, the pilot executed an immediate turn toward the runway. During the final approach, the pilot extended the flaps and landing gear.
Upon touchdown, the undercarriage was still in the process of extending and had not yet reached the locked position. As the aircraft moved along the runway, the landing gear collapsed, causing the aircraft to slide on its belly. There were no injuries to the pilot or the passenger, though the aircraft sustained damage to the propeller, the main landing gear, and the landing gear locker doors, hinges, and ribs.
The investigation
Investigators examined the engine and fuel systems following the accident. Although the pilot's pre-flight inspections had shown no signs of fuel contamination, approximately 50 cc of water contaminated with dirt was recovered from the aircraft's gascolator. While the exact origin of this moisture could not be confirmed, the maintenance engineer for the aircraft owner suggested that fuel contamination was a contributing factor to the engine failure.