Incident
The airplane ground looped during the landing roll. After touchdown, the pilot applied right rudder and the pedal became stuck in a near full forward position. The pilot was then unable to maintain directional control and the airplane turned approximately 270 degrees on the runway before coming to rest.
Investigation
A post-accident inspection revealed that the pin securing the right rudder pedal to the brake cylinder arm was missing. There was also evidence of aluminum shavings at the pin attachment point. The airplane manufacturer indicated that the pin can be installed either outboard or inboard of the cotter key. According to Figure 26 of the Parts Manual, the installation is depicted as inboard of the cotter key.
In this model, the battery is located in the forward section of the fuselage and a structural angle brace is installed for support. On the right pedal of the forward seat, the clearance between the pin and the angle brace is reduced if the pin is installed inboard of the cotter key. Installing the pin outboard of the cotter key allows for greater clearance between the pin and the angle brace.
Maintenance Background
An identical problem was discovered by the operator on the sister ship to the accident airplane. The pin on the sister ship was changed a few weeks before the accident. The operator intended to examine the rudder pedal pins on the accident airplane during the next scheduled maintenance period.