On August 13, 2018, about 1100 central daylight time, a Piper J3C-65 airplane, N42218, experienced a runway excursion during landing at Polly Ranch Airport (7XS0), Friendswood, Texas. The commercial pilot was not injured and the airplane sustained substantial damage. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident and no flight plan had been filed. The local flight departed at 1024. The responding Federal Aviation Administration (FAA) inspector spoke to the pilot who described the runway excursion. The pilot stated that the airplane touched down about 35 to 40 mph and as soon as the tail touched the runway the airplane veered to the right. The airplane continued off the runway into a tree. The pilot reported that he departed 7XS0 and completed several uneventful touch-and-go landings at two nearby airports. He returned to 7XS0 and landed on runway 11 with a right crosswind at 9 knots. As the airplane slowed on the runway it weathervaned into the wind and he was unable to steer with the tailwheel. The airplane exited the right side of the runway and collided with a tree. A postaccident examination of the airplane revealed that the Maule tailwheel locking mechanism pins were worn down and degraded. The locking mechanism could not withstand even a small amount of side pressure. As pressure was applied to the tailwheel, the locking mechanism would unlock and the tailwheel would swivel out of alignment (figure 1). Figure 1 – Unlocked Tailwheel