What happened
On 11 October 2010, a Silence Twister, registration G-TWSR, was conducting a private flight approximately 5 nautical miles north-east of Gloucestershire Airport. While at an altitude of 800 ft amsl, the pilot noted that the engine began running irregularly. Although oil temperature and pressure readings remained within normal parameters, the engine produced significant mechanical noise.
As the pilot initiated a descent to perform a precautionary landing, the engine ceased operation entirely when the aircraft reached approximately 700 ft amsl. The pilot subsequently landed the aircraft in a field that had been recently cultivated. During the landing roll, the main wheels sank into the soft soil, causing the landing gear legs to bend backwards and move into the stowed position. The aircraft came to a halt shortly after the impact.
The investigation
The investigation focused on the engine failure and the structural damage sustained during the landing. The pilot, who was uninjured, reported that emergency services were not required. A post-accident inspection of the aircraft revealed scratches to the wings and the underside of the fuselage. Crucially, the inspection of the engine identified that the crankcase had become distorted around the No 4 cylinder.