What happened
On March 27, 2006, at approximately 18:15 local time, a Cessna 172E with registration EC-HRX was conducting a dual-instruction flight near the Casarrubines del Monte airfield in the southwest of Madrid. The flight, operated by Álamo Aviación, included an instructor and a student pilot.
While flying at 3,000 feet and approximately 5 NM from the airfield, the engine experienced a sudden loss of RPM and stopped abruptly without prior warning. The instructor took control of the aircraft and attempted to restart the engine twice without success. The crew subsequently prepared for an emergency landing in a plowed field near Villamanta. To minimize impact speed, the instructor utilized maximum flap deflection and executed a controlled stall just before touchdown. The aircraft traveled approximately 10 meters along the ground. Both occupants were uninjured and able to exit the aircraft on their own.
The investigation
The investigation focused on the engine failure and the fuel levels present at the time of the incident. Post-accident inspections of the aircraft revealed that the fuel remaining in each tank was approximately 1.5 liters, which represents the unconsumable fuel for this model. No fuel leaks were detected in the engine, fuselage, or fuel lines, and the fuel filter was free of obstructions. The investigation also examined the pre-flight inspection procedures and the fuel gauge readings.
It was noted that during the pre-flight inspection, the crew relied on the cockpit fuel indicators rather than visually checking the fuel levels through the tank filler necks, as the necessary ladder was unavailable at the airfield. The investigation determined that the fuel selector valve was in the "BOTH" position, meaning fuel was drawn from both tanks equally.
Findings
- The engine failure was caused by fuel exhaustion.
- The crew did not visually verify the fuel levels in the tanks during the pre-flight inspection, relying instead on cockpit gauges.
- Due to the lack of intermediate markings on the cockpit gauges, the crew likely misinterpreted a fuel level of approximately 28% as being at the halfway mark.
- The aircraft sustained minor damage to the nose gear and propeller due to the irregular terrain of the landing site.
- Maintenance records indicated that the aircraft and engine had been maintained in accordance with required intervals.