Flight History
On 9 June 2020, a Piper PA-28R-200 aircraft, registration EC-HLV, operated by AEROFAN ATO, departed from Madrid-Cuatro Vientos Airport (LECU) with two instructor pilots on board. The purpose of the flight was to practice landings and take-offs and to test the aircraft after an extended period of inactivity. After three uneventful landings and take-offs, the pilots decided to perform a short local flight. While over Valmojado, they simulated an engine failure by reducing the throttle to idle, at which point the engine began to run erratically. They increased power and returned toward LECU; the engine gauges indicated normal values and the engine responded as expected. At approximately 3000 ft above Navalcarnero, while flying at 120 kts with maximum power, the engine began producing small but regular explosive noises and vibrated violently. Difficulty maintaining level flight prompted the crew to divert to the nearby Casarrubios del Monte Aerodrome (LEMT) for an emergency landing. During the diversion, the aircraft's electrical power was interrupted, hindering communications. The pilot flying began a right turn to join the downwind leg for runway 08, but the pilot-in-command considered it more direct to proceed to the base leg for runway 26 and attempted to take the controls. The pilot flying then turned toward the base leg for runway 26; after electrical power was restored, the pilot-in-command instructed the pilot flying to take the controls.
Injuries and Damage
Both occupants, who were flight instructors, were uninjured. The aircraft sustained damage to its propeller, flaps, and the underside of the fuselage. The landing gear was not extended at the time of impact.
Investigation Findings
The investigation determined that the aircraft landed with its landing gear retracted due to a lack of adherence to operational procedures. Contributing factors identified included the override of the automatic landing gear extension system and the loss of engine power resulting from the failure of cylinder no. 4 due to improper engine maintenance.
Causes and Contributing Factors
The accident was caused by a lack of adherence to operational procedures, which led to the aircraft landing with its landing gear retracted. Factors thought to have contributed were the override of the automatic landing gear extension system and the loss of engine power from the failure of cylinder no. 4 due to improper engine maintenance.
Safety Recommendations
The investigation issued an operational recommendation to Spain's National Aviation Safety Agency (AESA) to monitor SINMA AVIACIÓN, S.L., regarding its approval as Maintenance Organization ES.145.113; a recommendation to SINMA AVIACIÓN, S.L. to ensure correct performance of maintenance overhauls and update best practices; and a recommendation to AEROFAN ATO to ensure adequate preparation during briefing meetings for instructor retraining flights.