What happened
On July 23, 2007, a Piper PA-28-180, registration PH-SNE, performed an unplanned landing at Midden-Zeeland Airport after encountering critical fuel levels. The flight originated from Seppe, France, with a scheduled stop at Liverpool John Lennon Airport in the United Kingdom for cargo and refueling before returning to France.
During the refueling process in Liverpool, the pilot requested 80 liters of fuel, split equally between the left and right tanks. While the pilot performed a visual check of the tanks prior to departure, the tanks were not completely full, providing limited information regarding the actual volume. During the return leg, the pilot operated the engine with a leaned mixture and reduced RPM to conserve fuel. However, while crossing the English Channel, the pilot realized the remaining fuel was insufficient to reach the original destination. After notifying flight information services, the aircraft landed at Midden-Zeeland, which had already closed for the night. Upon inspection the following day, authorities found both fuel tanks to be nearly empty.
The investigation
The investigation focused on the discrepancy between the pilot's calculated fuel reserves and the actual fuel consumed. The aircraft has a total capacity of 50 US gallons, but only 48 US gallons are considered usable. Based on the pilot's records, the total fuel used during the entire trip was approximately 175 liters, resulting in an average consumption rate of roughly 43 liters per hour. This represented a 23% increase over the 35 liters per hour specified in the aircraft's flight manual.
Investigators examined the refueling records in Liverpool and confirmed that the fuel was indeed provided in liters, dismissing the pilot's concern that the amount might have been measured in pounds. The investigation also noted that the left fuel gauge was marked with a sticker indicating it was an "unreliable tanksender."
Findings
- The primary cause of the incident was inadequate flight planning regarding actual fuel consumption.
- There was an over-reliance on fuel gauges, which are notoriously imprecise in general aviation aircraft and should only be used for confirmation rather than exact measurement.
- The actual fuel burn significantly exceeded the theoretical values provided in the pilot's manual, likely due to variables such as aircraft weight, power settings, or leaning techniques.
- A lack of precise verification during the refueling process contributed to the uncertainty of the available fuel volume.