What happened
On October 2, 2011, a SMG 92 TurboFinist, registration HA-YDM, landed at Hradec Králové Airport following a parachute jump mission. After touchdown on runway 16R, the pilot utilized the propeller's reverse thrust (Beta mode) to assist in decelerating the aircraft.
During the landing roll, while the pilot was transitioning the propeller from ground Beta mode to flight Beta mode, they simultaneously moved their feet from a low to a high position on the rudder pedals. In doing so, the pilot unintentionally applied the main landing gear brakes. This sudden application of braking force, combined with the reverse thrust, created a significant nose-down pitching moment. The aircraft's nose pitched forward abruptly, causing the propeller to strike the grass runway surface. The impact resulted in the bending of all three propeller blades and damage to the engine cowling and starter-generator. As the aircraft's momentum shifted, the tail subsequently lifted and then struck the ground, causing structural damage to the tailwheel attachment point.
The investigation
The ÚZPLN investigation focused on the mechanical state of the aircraft and the sequence of pilot inputs during the critical phase of the landing roll. Technical inspections of the engine and control systems revealed no mechanical failures or defects that would have hindered the pilot's ability to control the aircraft. The investigation confirmed that the engine responded correctly to the pilot's inputs and that the weather and runway conditions were not contributing factors to the incident.
Findings
- The pilot was properly licensed and held a valid medical certificate.
- The aircraft was fully airworthy with valid maintenance and insurance.
- The primary cause of the accident was the simultaneous application of the wheel brakes and the engine's reverse thrust mode, which induced the nose-down pitch.
- The pilot was unable to prevent the propeller strike once the nose began to pitch forward due to the sudden deceleration.