Piper PA-23 Aztec Door Opening Incident in Castellón (EC-AZV)

Incident Overview and Flight Details On Wednesday, July 18, 2007, at 11:15 local time, a Piper PA-23 Aztec with registration EC-AZV, operated by Aeroclub de Sabadell, was conducting a private general aviation flight from Sabadell Aerodrome (LELL) to Requena Aerodrome (LERE). The aircraft was a twin-engine model powered by two Lycoming IO-540-C4B5 engines. The flight was in the en-route phase when the incident occurred. ## In-Flight Event and Emergency Landing During the flight, the aircraft's single right-side access door opened at an altitude of 4,000 feet. The pilot reported that this caused vibrations, which he attempted to mitigate by first reducing the aircraft to a low cruise configuration and then to a slow flight configuration. Due to the inability to maintain normal control of the aircraft, the pilot decided to make an emergency landing. The aircraft landed in the municipal area of Cabanes, Castellón, at the 1.5 km mark of the CV-157 road, in a construction zone. During the landing, the aircraft traveled approximately 100 meters on the ground before turning left and coming to rest in the roadside ditch. The soft and irregular terrain prevented the pilot from maintaining full control during the landing, contributing to the deviation and final position. ## Aircraft Damage and Occupant Status The aircraft sustained significant damage. The three occupants—one pilot and two passengers—were uninjured and evacuated the aircraft under their own power. No other damage was reported. ## Aircraft Door System and Maintenance History The Piper PA-23 Aztec has a single access door on the right side that opens forward by rotating on a vertical axis. The door closure system includes a lock designed to be disengaged for voluntary opening from the interior. Post-accident inspection found no anomalies; the door opened and closed normally, and the lock functioned correctly. Maintenance records indicated three actions on the door of this aircraft: one in June 2007 following a report of malfunction, and two as part of scheduled inspections in March 2007 and April 2005. There were also five maintenance actions on the door of another aircraft of the same model from June 2006 to March 2007. The aeroclub and pilot noted previous instances of in-flight door opening on this aircraft and another of the same model, though specific repairs could not be documented. ## Training and Emergency Procedures The Aeroclub de Sabadell reported that during multi-engine qualification training, pilots undergo practical training for the door-opening emergency. The procedure involves reducing speed to 90 mph, opening the left-side window, and closing the aircraft door. The pilot applied this procedure during the incident, with the cooperation of the passengers. ## Analysis and Probable Cause The door locking system is complex and designed so that the door can open even if the lock is engaged, in case of a jam. If the door had been opened without removing the lock system, forcing the system could have caused a misalignment, preventing proper closure and lock engagement. If the lock lever was not properly set, the door might not have been fully closed, and vibrations during flight could have opened it. The door opens against the airflow, which would normally prevent full opening. It is also possible that the lock lever was inadvertently actuated due to its accessible position. The pilot's decision to land as soon as possible was considered appropriate, and the chosen location, a construction zone with characteristics similar to a dirt runway, was deemed suitable. However, the soft and irregular terrain during landing prevented full control, leading to the left turn and ditch landing. The probable cause of the accident was the opening of the door during flight, possibly due to incorrect locking, which caused severe vibrations that prevented control of the aircraft and forced an emergency landing on excessively soft and irregular terrain.