What happened
On June 12, 2010, a privately operated Valentin Taifun 17EII, registration JA2553, departed Takasu Gliding Field in Mie Prefecture for a routine engine test flight. The flight, which included the pilot and one passenger, lasted approximately 30 minutes and involved maneuvers over Matsuzaka City.
During the final approach to Runway 1 and 4, the aircraft was flying at an airspeed of approximately 62–65 mph with the flaps set to +15°. As the aircraft descended to a height of roughly three to five meters above the ground, the nose abruptly dipped. This sudden drop prevented the pilot from performing a proper flare, causing the propeller to strike the ground first, followed by the nose landing gear. The impact resulted in two serious injuries and substantial damage to the airframe, including broken propeller blades and structural cracks in the fuselage and wings.
The investigation
The JTSB investigation examined the aircraft's maintenance records, flight logs, and the environmental conditions at the time of the accident. Investigators analyzed the aircraft's configuration, noting that while the flight manual recommends a minimum approach speed of 100 km/h (62 mph) with flaps at +30°, the pilot had opted to maintain +15° flaps to simplify glide angle adjustments using the air brakes.
Investigators also assessed the meteorological conditions and the physical landscape of the landing site. They noted the presence of a large mass of reeds near the runway shoulder and a significant wind gradient effect. Furthermore, the investigation looked into the visibility of the windsock, which was partially obscured by a parked vehicle and was smaller than standard equipment, making accurate wind assessment difficult for the pilot.
Findings
- The primary cause of the accident was a hard landing triggered by a sudden nose drop just before the flare.
- This nose drop was likely caused by turbulence resulting from wind shear and the aerodynamic interference of the nearby reed beds.
- The use of +15° flaps instead of the recommended +30° likely contributed to a loss of lift during the encounter with the turbulence.
- The pilot's ability to accurately assess surface wind was hindered by the obscured and undersized windsock, as well as the lack of ground-based radio communication or anemometers.