On June 25, 2000, a Piper PA-18A-150, N6775B, registered to Seattle Glider Council, Inc. of Ephrata, Washington, was substantially damaged in a loss of control and subsequent main landing gear collapse on landing rollout at Ephrata, Washington. The commercial pilot-in-command and a private pilot aboard the aircraft (a Canadian citizen who held a Canadian glider pilot license and a Canadian private pilot license for single-engine land airplanes, but whose U.S. private pilot certificate carried only a glider rating) were not injured in the accident. Visual meteorological conditions prevailed and no flight plan was filed for the 14 CFR 91 local instructional flight from Ephrata. The accident airplane was used as a glider tow plane by the Seattle Glider Council. The pilot-in-command reported that on the accident flight, he was getting checked out on the aircraft by the private pilot, whom the pilot-in-command reported was the glider club's "check out pilot". He stated: ...The approach and landing went smoothly. About 100 feet into the roll-out the left wing lifted, so I applied left aileron to bring it down. With that the aircraft began to veer to the left so I corrected with a small amount of right rudder. Then the aircraft began to go right so I applied some left rudder. That did not correct the problem so I applied more left rudder, until it was full left rudder still with no response. I moved for the left brake. By this time the aircraft was close to 90 degrees turned on the runway. At that time [the private pilot] applied a large amount of power and the airplane whipped to the right, the left gear broke and the left wing hit the ground. The private pilot (the club "check out" pilot) reported: ...I asked [the pilot-in-command] to fly a pattern for runway 02 and using a steep approach as we normally use while towing gliders because of the two hundred foot tow rope in order to keep the tow rope a safe distance from the threshold. The landing was smooth but while rolling straight ahead at a decreased speed, the left wing came up and the airplane started to turn slightly to the right. I applied power to take over the controls but the rate of turn to the right increased and [I] realized that it would not be possible to recover. At that time I then retarded the throttle and the airplane came to a stop. The left wing was broken and the left wing tip was on the ground.... The operator's accident report to the NTSB indicated that no mechanical malfunction or failure was involved in the accident. The landing on which the accident occurred was on runway 2, a 6,700- by 150-foot asphalt runway equipped with visual approach slope indicator (VASI) lights. Winds were reported from 020 degrees true at 7 knots in the 0850 Ephrata METAR observation, and from 070 degrees true at 7 knots in the 0950 Ephrata METAR observation.