Incident Overview
A pilot returning from a local flight elected to land on a grass turf runway. The runway included an asphalt runway intersection within the first quarter of its length. The pilot reported a landing speed of about 60 mph and touched down long on the initial portion of the grass turf. After initially holding off lowering the tail wheel, the pilot lowered it firmly onto the ground.
Sequence of Events
During the landing roll on the asphalt section, the airplane began to arc to the left. The pilot applied full right rudder and then a slight amount of right brake. As the airplane departed the asphalt and transitioned back to the grass turf, it abruptly nosed over. The propeller struck the ground, and the airplane came to rest inverted on the grass turf runway. The accident resulted in substantial damage to the vertical section and rudder.
Runway Transition Inspection
An inspection of the asphalt-to-grass turf transition revealed that the airplane's main landing gear tires had dug into the turf as it left the slightly higher asphalt surface.
Mechanical Findings
An aviation safety inspector from the Federal Aviation Administration responded to the accident scene and interviewed the pilot, who reported no mechanical malfunctions or failures during the landing and rollout. However, while the airplane was being repaired after the accident, a mechanic discovered that the bolts holding the main wheel halves in position were excessively long. This condition allowed the wheel halves to separate and the brake discs to change position when the airplane transitioned from the asphalt to the turf runway.