What happened
On 24 August 2003, a Cessna U2/06F Stationair, registration G-STAT, was conducting aerial work for parachute dropping at Strathallan Airfield in Perthshire. After completing one flight and during the second, the aircraft's engine ceased operation while at an altitude of approximately 800 feet.
Prior to the failure, the pilot had been utilizing the right fuel tank. Upon the engine stopping, the pilot switched the fuel selector to the left tank and attempted an engine restart, which was unsuccessful. Following emergency radio communications, the pilot performed necessary checks and executed a forced landing into a field. During the approach, the aircraft's airspeed decreased significantly, potentially leading to a stall before the aircraft impacted a fence at the edge of a ditch. The pilot sustained minor injuries and was briefly pinned by the instrument panel before exiting the wreckage. The aircraft was damaged beyond economic repair.
The investigation
The investigation focused on the fuel state and the pilot's management of the fuel system. Examination of the fuel tanks showed that while the left tank contained 30 gallons, the right tank was empty. Although the pilot had refuelled prior to the flights, there was no precise method for measuring individual tank quantities, and the gauges were known to fluctuate during engine operation.
It was established that the pilot had not switched the fuel selector during the second flight, which was a departure from his usual practice of changing tanks once per flight. Additionally, the investigation found that the pilot did not activate the electric fuel booster pump when switching tanks, a step advised by an aircraft placard when moving from a dry tank to a fueled one. This omission likely prevented a successful engine restart.
Findings
- The engine failure was caused by the exhaustion of fuel in the right tank.
- The pilot failed to change the fuel selection during the second flight, leading to the depletion of the active tank.
- The pilot's attention was diverted by monitoring high engine oil temperatures and concerns regarding climb performance.
- The failure to use the electric fuel booster pump during the fuel selector change likely hindered the engine's ability to restart.
Safety action
Following the incident, the pilot underwent further training. The aircraft operator implemented new procedures requiring pilots to change the fuel tank selection once during the climb and once during the descent for every parachute dropping flight.