What happened
On 9 August 2001, a Grob G115, registration G-BOPU, was conducting a training flight at Manchester (Barton) airfield. The flight, involving a student and an instructor, was intended as a circuit detail using Runway 32. Following a preflight inspection and engine start, the aircraft taxied to the runway threshold. At this time, the fuel gauge indicated the tank was full.
During the flight, while the aircraft was approximately 800 feet above the ground on a left-hand circuit, the engine lost power. The instructor took control of the aircraft and declared a Mayday. Due to the presence of nearby power cables and pylons, a landing on the active runway was deemed too risky. The instructor identified a golf course fairway to the west of the airfield as a suitable emergency landing site. After executing emergency procedures, the aircraft landed on the fairway. During the landing, the aircraft struck a grass bank, causing the nosewheel to fail and resulting in damage to the propeller and nosegear. There were no injuries to the two occupants.
The investigation
Investigators discovered that the fuel tank was entirely empty upon arrival at the scene, despite the gauge showing a full reading when the battery master was switched on. The investigation revealed that an annual inspection had been completed on the same day, which required the removal of the fuel tank. Following this, the aircraft had been refuelled with approximately 30 litres of fuel. The maintenance engineer noted that while the gauge indicated a full tank, they did not reconcile this reading with the actual amount of fuel added.
The investigation also examined the fuel gauging system, which uses a plastic float and a resistance wire sensor. While the maintenance organization found no faults in the system, it was concluded that the float had likely become stuck in the full position. Because the tank's location prevented any visual inspection or the use of a dipstick, the crew had no way to verify the actual fuel level.
Findings
- The engine failure was caused by fuel exhaustion.
- The fuel gauge provided an inaccurate reading because the transmitter float was stuck at the full position.
- The maintenance engineer failed to notice the discrepancy between the fuel quantity added and the gauge indication during refuelling.
- The flight crew relied solely on the fuel gauge without a secondary method of verification, as the aircraft type lacked a visual sight gauge.
- There was no established procedure for reconciling fuel uplift and usage against the aircraft's fuel state.