What happened
On 27 August 1999, a Piper PA-28-161, registration G-BUJP, was performing a private flight near Welshpool Airfield. After completing a short flight, the pilot returned to the airfield and descended to a circuit height of 1,500 feet. During the downwind leg, the pilot performed standard checks, which included the use of carburettor heat.
As the aircraft transitioned to the base leg and subsequently the final approach, the pilot attempted to adjust the throttle to maintain the correct descent path. During this maneuver, the engine failed to respond to throttle inputs. The pilot attempted to troubleshoot by checking the electric fuel pump and switching between the left and right fuel tanks. While the engine briefly responded after switching back to the right tank, it soon lost all power completely.
Recognizing the emergency, the pilot declared a Mayday and identified a suitable field for a forced landing. The aircraft descended over a line of trees and touched down in a field approximately 200 metres in length. While the initial touchdown was successful, the rough terrain and the presence of bushes and barbed wire at the field boundary caused the aircraft to veer. The right wing struck a tree, causing damage to the wing attachments and the fuel tank, resulting in a fuel leak. There were no injuries to the pilot or the passenger.
The investigation
The investigation focused on the cause of the engine power loss and the condition of the aircraft. The pilot noted that while the engine had operated normally during previous uses of carburettor heat earlier in the flight, he could not confirm if the heat had been applied during the base leg.
Meteorological data for the time of the accident showed an air temperature of 17°C and a dew point of 10°C. According to standard carburettor icing charts, these conditions were within the range where moderate icing is expected at cruise power and serious icing is expected at descent power. Additionally, the investigation noted that the left fuel tank gauge had been malfunctioning, incorrectly indicating a full tank during the flight. The aircraft had also experienced similar engine issues in the days immediately preceding the accident.