What happened
On 19 March 2021, a Cessna 172P, registration EC-FJS, was conducting a return training flight from Seville to Cuatro Vientos when the engine began misfiring at approximately 4,500 ft over the River Tagus. The crew, consisting of an instructor and a student, attempted to manage the power loss by adjusting the mixture and activating carburettor heat. While the engine temporarily recovered during a go-around at Camarenilla Aerodrome, the power loss recurred as the aircraft approached Casarrubable del Monte.
The engine eventually ceased operation entirely, forcing the crew to perform an emergency landing in a field. During the landing at approximately 50 kt, the nose gear collapsed, causing the aircraft to flip onto its back. Both occupants were unharmed, though the aircraft sustained significant damage to the fuselage, wings, and vertical stabilizer.
The investigation
The CIAIAC examined the aircraft's maintenance records, engine components, and fuel consumption logs. Investigators found no evidence of mechanical malfunction in the engine, spark plugs, or magneto system. The inspection of the carburettor heating system also revealed no defects.
Analysis of the flight logs and weather data indicated that environmental conditions, including a dew point of 0ºC, were conducive to carburettor ice formation, which may have caused the initial engine misfires. Furthermore, fuel consumption calculations suggested that the aircraft was operating with very low reserves. Based on the flight duration and headwind conditions, it was estimated that only about 4.63 gallons of fuel remained at the time of the landing.
Findings
- The engine failure and subsequent emergency landing were primarily driven by inadequate flight planning regarding fuel management.
- The aircraft did not have sufficient fuel reserves to meet the regulatory requirement of flying to the intended destination and maintaining flight for an additional thirty minutes.
- Environmental conditions were favorable for the formation of ice in the carburettor, which likely contributed to the initial engine instability.
- There were no mechanical or structural failures found in the engine or airframe prior to the impact.