Incident Overview
During the landing roll, as the nosewheel contacted the runway, the pilot detected a strong vibration in the rudder pedals. In response, the pilot abruptly applied backpressure on the control yoke, causing the airplane to become airborne again. When the backpressure was released, the airplane touched down on the nosewheel and began porpoising. After four oscillations, the airplane decelerated sufficiently for the pilot to initiate a turn onto a taxiway. As the airplane exited the runway, the nose settled onto the asphalt surface.
Damage and Examination
Post-incident inspection revealed that the fuselage was buckled along the cabin area above both the left and right wing roots. The nosewheel had separated from the piston and fork assembly. Examination of the flight control system and nose wheel fork and strut assembly found no anomalies. The nosewheel axle and rim fractures displayed features and deformation consistent with overstress fractures, with no evidence of preexisting cracks. The inner race and rolling elements of the left bearing were displaced to the left and bent in the area of the displacement. A circumferential crack was present on the upper surface of the axle at the location corresponding to the right edge of the left bearing inner race. Additionally, an impact mark was observed on the upper surface of the axle, consistent with heavy contact with the left bearing inner race.
Investigation Findings
The investigation determined that the fractures were overstress in nature, with no preexisting cracks or defects identified. The flight controls and nose gear components functioned normally apart from the separated nosewheel. The sequence of events indicates that the porpoising and subsequent hard landing led to the structural damage and component failure.