What happened
On August 2, 2024, during a gliding competition, a TwinShark 304 TS with registration D-KDRG was completing a long-duration flight of nearly seven hours. As the aircraft approached the Rieti airport, the pilot realized the altitude was insufficient to reach the destination. In an attempt to maintain flight, the pilot deployed the retractable engine.
While the engine deployment was successful, the engine failed to start. The pilot believed this was due to the failure to operate the manual fuel pump as required by the flight manual. The deployment of the engine increased aerodynamic drag, which significantly increased the rate of descent. Faced with a rapidly declining altitude and the presence of power lines in the vicinity, the pilot opted for an off-field landing in a nearby meadow. Although the terrain appeared flat, it was marked by deep furrows. The aircraft struck a significant furrow approximately 40 meters into the landing roll, causing heavy damage to the fuselage and structural components. The pilot remained uninjured, but the passenger sustained serious injuries.
The investigation
The ANSV investigation focused on the sequence of events leading to the engine failure and the subsequent landing. Investigators examined the aircraft's maintenance records, which were found to be in order, and performed functional tests on the propulsion system following the accident. These tests confirmed that the engine and propulsion system were fully operational.
Physical evidence from the crash site showed a contact track of approximately 80 meters. The investigation noted significant damage to the lower fuselage, structural deformations, and damage to the vertical and horizontal stabilizers. The tail boom was found to have broken at the trailing edge of the wing. The investigation also confirmed that the engine deployment process, while successful, increased drag, which was a critical factor in the descent rate.
Findings
- The primary cause of the accident was the incorrect engine start procedure, specifically the failure to use the manual fuel pump, which prevented the engine from starting.
- The deployment of the engine increased drag, which forced the pilot to execute an emergency landing away from the aerodrome.
- The impact with a deep furrow in the field caused the severe injuries to the passenger and the extensive damage to the TwinShark 304 TS.
- Contributing factors included pilot fatigue following a long-duration flight and the pilot's determination to complete the competition without relying on engine power.