What happened
On March 3, 2004, a Diamond DA40-180 aircraft, registration EC-IQE, was performing a dual flight training mission at Seville Airport. As the aircraft began its takeoff run at a very low speed, the rear door suddenly detached from the fuselage and became separated from the aircraft.
Following the detachment, the aircraft veered off the runway via the first available taxiway. The crew immediately notified the control tower, and a signals vehicle was deployed to retrieve the door from the runway. There were no injuries to the instructor or the student pilot, and the aircraft sustained only minor damage.
The investigation
Investigators examined the aircraft and found that the two hinges connecting the upper part of the door to the fuselage had broken at the point where they join the door. Notably, the attachment points on the fuselage frame remained in perfect condition, and the door's latching mechanism was found to be functioning correctly. The inspection revealed that if the door had been properly closed and then detached, it would have caused significant damage to the surrounding fuselage, which was not observed.
The investigation also reviewed the operator's checklists. While the "BEFORE START" and "AFTER START" checklists included items regarding the door and the annunciator panel, the investigation focused on the "BEFORE TAKE OFF" procedures. It was noted that the crew typically leaves the front canopy in position 2 for ventilation during taxi, a practice permitted by the flight manual.
Findings
- The investigation established that the rear door was not closed at the start of the takeoff roll.
- The crew likely ignored the warning light on the annunciator panel during taxi because the light is triggered by both an open rear door and an open front canopy; since the canopy was intentionally left open for ventilation, the warning was expected.
- The failure to complete the "BEFORE TAKE OFF" checklist meant the open door went unnoticed.
- The design of the door hinges is such that they break almost immediately if the aircraft moves while the door is unlatched.
- A contributing factor was the design of the cockpit warning system, which does not allow the pilot to distinguish whether the light is indicating an open canopy or an open rear door.
Safety action
- It is recommended that the operator, Aerotec, implement measures to ensure crews strictly adhere to all applicable checklists.
- A recommendation was made to EASA to require the type certificate holder to modify the door-open warning system design to allow for the unambiguous identification of the specific open component.