On May 15, 1999, at 1754 Alaska daylight time, a tailwheel equipped Piper PA-20 airplane, N8883C, sustained substantial damage when it departed the left edge of runway 19 at the Dillingham Airport, Dillingham, Alaska. The commercial pilot and sole passenger were not injured. The airplane was being operated under 14 CFR Part 91 as a personal flight by the pilot and his wife. The pilot originally intended to depart for the village of Ekuk, but was returning to park after taxiing for takeoff. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The pilot told the NTSB investigator-in-charge (IIC) during a telephone interview on May 18, that during taxi, the airplane did not steer correctly, but he could not determine the reason. He told the IIC that he decided to return to parking. During the return taxi on runway 19, the airplane ground looped to the left, and the pilot was unable to control the turn with rudder input or wheel brakes. The tailwheel went off the left side of the runway onto uneven ground, damaging the tailwheel support structure and center empennage. The pilot told the IIC that after the accident, he discovered the external rudder gust lock still installed. Reported winds at the time of the accident were 210 degrees at 7 knots. Runway 19 measures 6,404 feet long by 150 feet wide.