What happened
On June 2, 2017, at approximately 08:20 local time, a private Europa aircraft, registration HB-YJF, was performing a takeoff from runway 25 at Grenchen Airport (LSZG). During the takeoff roll, the aircraft failed to accelerate as anticipated. In response, the pilot initiated an aborted takeoff when the aircraft reached a speed of approximately 45 knots, roughly halfway down the runway.
During this deceleration phase, the pilot-side door suddenly opened, and the plexig_glass window was torn from its frame. This event caused the pilot to momentarily lose control of the aircraft, resulting in the plane veering across the left runway boundary. The aircraft's wings struck the runway edge lighting, causing damage to the flaps on both wings. To prevent the aircraft from rolling toward a nearby main road, the pilot steered the plane into a small grain field near the end of the runway.
There were no injuries to the pilot or the passenger, though the aircraft sustained light damage and the runway lighting was impacted.
The investigation
Investigators examined the door locking mechanism to determine why the cockpit door failed. A subsequent inspection of the locking mechanism revealed no mechanical defects. Furthermore, footage from a cockpit-mounted camera confirmed that the locking lever had been moved to the fully forward "locked" position prior to the start of the takeoff.
Findings
While the mechanism was functional, the investigation established that the door could be closed in a manner where the rear locking bolt does not properly engage with the socket, instead resting outside the fuselage. Under sufficient aerodynamic pressure, the front bolt can extend, causing the door to open and protrude by approximately 5 cm, leading to the unintended door opening observed during the high-speed portion of the takeoff roll.