PA-18 REPLICA N3AK accident near Ronan, Montana

Probable cause

A jammed tailwheel assembly, which resulted in the pilot’s inability to maintain directional control upon landing.

NTSB analysis

The private pilot, who was also the owner/builder of the airplane, reported that he had flown a left traffic pattern in the tailwheel-equipped airplane and that the wind was light and variable. The pilot then conducted a wheel landing, and he reported that it was normal. However, immediately after he lowered the tailwheel to the runway, the airplane veered rapidly right and then skidded off of the runway into grass.

On-scene examination of the wreckage revealed that both of the tailwheel chains that normally connected the rudder horns to the tailwheel steering arms were disconnected from their respective springs. The end link of one of the chains was fractured, whereas the end link of the other chain was intact. The chains were different lengths, which was consistent with the possible failure and loss of one or more links. During subsequent disassembly of the tailwheel pivot mechanism, some springs and internal components were found fractured, and at least one of the springs was found jammed, which prevented the tailwheel from pivoting.

Although the investigation could not determine when or why the chains failed or became disconnected, significantly increased or complete resistance to tailwheel pivoting could result in the failure of one or both chains. The available evidence is consistent with the tailwheel having become jammed, and possibly uncontrollable, in a noncentered position during flight, which resulted in the airplane entering a right veer during the landing roll from which the pilot could not recover. The maintenance technician who disassembled the tailwheel after the accident reported that the damage to the pivot mechanism did not result from the accident.

Text from the NTSB. Open the NTSB docket for WPR12LA348 for the full record.