What happened
On January 30, 2005, at approximately 13:00 h, a CASA 1131-E Bücker, registration EC-FSS, departed from the Mutxamel Aerodrome in Alicante for a non-commercial flight intended for familiarization. The flight was operated by the Aeroclub de Alicante with a pilot and one passenger on board. Meteorological conditions at the time were favorable, characterized by good visibility and no wind.
Following standard procedures, the crew performed engine warm-up and magneto checks, maintaining the idle speed above 8/00 rpm. However, immediately after takeoff, the engine began to malfunction. Witnesses on the ground observed white smoke emitting from the exhaust. Although the engine did not stop completely, it failed to produce sufficient power. After reaching an altitude of approximately 300 ft, the pilot attempted to return to the airfield by turning right, but due to a continuous loss of altitude and airspeed, an emergency landing was executed in a flat, stony area covered with shrubs and trees.
The impact caused significant damage to the forward section of the aircraft, including a deformed landing gear, severe deformation of the wings, and a destroyed propeller. The pilot and passenger sustained only minor abrasions and light bruising from their seatbelts and were able to exit the aircraft unaided.
The investigation
Investigators examined the engine and the aircraft's maintenance history. While the external inspection of the engine showed no obvious signs of failure prior to impact, internal inspections revealed that the spark plugs for cylinders 1 and 3 were coated in oil, with cylinder 3 showing burnt oil residue. Low compression was noted in cylinder 4, and dirt ingress was found in the intake valve of cylinder 2.
The investigation also reviewed the aircraft's fuel system and operating procedures. The fuel selector valve featured three positions: reserve, primed, and open. The manufacturer's instructions for pre-takeoff checks specifically required the fuel selector to be set to the RESERVE position to ensure consistent fuel supply during all power settings. The investigation found that the pilot typically used the OPEN position instead.
Findings
- The primary cause of the engine malfunction was the selection of the OPEN position instead of the RESERVE position on the fuel selector valve. This error led to the depletion of fuel within the fuel lines during the high-power demand phase of takeoff.
- The presence of white smoke observed by witnesses was consistent with an engine running on an overly lean mixture due to insufficient fuel supply.
- The pilot was unfamiliar with certain specific operating procedures required for this aircraft type.
- The aircraft had seen very low utilization, with only 22 hours and 19 minutes flown in the ten months preceding the accident.