What happened
On 13 March 2011, a Jodel D117A, registration G-ASXY, was conducting a private flight from Cardiff International Airport to Haverfordwest Airfield. During the cruise phase of the flight, the aircraft experienced a sudden drop in engine RPM from approximately 2,200 to 1,000. The commander immediately transitioned to a 50 kt glide and notified Swansea Radio of the emergency.
In response to the power loss, the commander selected a field for a forced landing. During the approach, the aircraft flew across the chosen pasture at a height of roughly 15 ft. As the aircraft traversed the field, it clipped the tops of a tree row and subsequently struck a power cable suspended between telegraph poles. The impact with the cable caused the aircraft to rotate about its left wing and land in an inverted position. The commander sustained fatal injuries, while the co-pilot suffered serious injuries.
The investigation
The AAIB examined the engine, fuel systems, and the accident site. Testing of the Continental Motors C90-14F engine on a dynamometer showed it performed within specifications, though it produced slightly less power than rated at maximum RPM. The fuel and venting systems were found to be unobstructed, and the fuel samples showed no contamination.
Investigators also reviewed meteorological data, noting that while the aftercast did not indicate severe icing, the temperature and dew point conditions were such that carburettor icing could have occurred during descent or at cruise power. The investigation also noted that the aircraft's engine was running at 1,000 rpm during the landing, which provided more thrust than a typical idle speed, potentially contributing to the overshoot.
Findings
- The aircraft overshot the selected landing field and struck a power cable.
- The power cable was obscured by the trees at the edge of the field.
- The engine power loss could not be definitively proven, but the most likely cause was carburettor icing.
- The engine was operating at a higher RPM than typical idle during the forced landing, which may have affected the descent profile.