What happened
On October 24, 2006, a Diamond DA 42 landed on runway 27 at Hannover International Airport under visual flight rules. As the pilot was decelerating on the runway at approximately 60 knots, the left main landing gear strut collapsed. The aircraft subsequently veered off the paved surface and came to a stop on a grass area adjacent to the runway, approximately 900 meters beyond the runway threshold.
The two occupants of the aircraft were able to exit the wreckage uninjured.
The investigation
The BFU investigation focused on the structural integrity of the landing gear assembly. The aircraft was equipped with a hydraulic retractable landing gear system, where the actuation cylinder and locking mechanism of the main gear struts are bolted to a glass-fiber reinforced plastic (GFRP) mounting plate. This plate is bonded to the aircraft's main spar.
Upon inspection of the wreckage, investigators discovered that the GFRP mounting plate had detached from the main spar. This separation rendered the landing gear strut free to move, leading to the collapse during the landing roll. The investigation also noted extensive secondary damage to the aircraft, including abrasions to the left propeller blade tips, damage to the left aileron, the left outer flap bearing fairing, the pitot tube, and the tail skid. Additionally, the landing gear door was torn from its hinges, and the wing skinning near the gear well had separated from the spar.
Findings
- The primary cause of the accident was the detachment of the GFRP mounting plate from the main spar, which caused the left main landing gear to collapse.
- The aircraft sustained heavy damage to the propeller, control surfaces, and wing structure due to the impact and subsequent excursion onto the grass.