What happened
On 23 April 2006, a Zenair CH 601HDS, registration G-OANN, was conducting a private flight from North Moor Airfield, near Scunthorpe, to Perth (Scone) Airfield in Scotland. During the flight, the pilot transferred fuel from the starboard wing tank to the header tank. While the pilot expected the header tank gauge to show a decrease in level as fuel was added, the gauge remained at a full reading. This led the pilot to suspect either an unrecorded fuel leak or an unusually high fuel consumption rate, though the pilot chose to rely on endurance calculations rather than the gauge reading.
After a brief stop at Perth Airfield, the engine ceased operation. The pilot attempted to restart the engine while en-route to Charterhall Airfield, but these efforts failed. While establishing radio contact and preparing for a downwind join to Runway 21, the engine stopped again at approximately 1,000 ft. Realising a forced landing was unavoidable, the pilot landed the aircraft in a nearby farmer's field. The aircraft sustained severe damage, but the pilot sustained only minor injuries.
The investigation
The investigation examined the engine failure and the pilot's management of fuel indications. The pilot noted that the header tank gauge had failed to reflect the fuel transfer, remaining at a 'full' reading despite the addition of fuel. The pilot also considered the possibility of carburettor icing as a potential cause for the engine stoppage.