On February 1, 2007, about 0945 Alaska Standard time, a ski-equipped Piper PA-12 airplane, N3233M, sustained substantial damage when it collided with snow-covered terrain while maneuvering to land on a remote lake, about 30 miles northwest of Glennallen, Alaska. The airplane was being operated as a visual flight rules (VFR) local area personal flight under Title 14, CFR Part 91 when the accident occurred. The airplane was operated in visual meteorological conditions by the pilot/owner of Copper Valley Air Service, LLC, Glennallen. The commercial certificated pilot was not injured. The sole passenger received minor injuries. The flight originated at the Gulkana Airport, Gulkana, Alaska, about 0920, and no flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on February 2, the pilot reported that he and the passenger were scouting the area for a wolf hunt, and decided to land on a frozen lake. While making a slight left turn toward the landing area, he said he encountered a windshear about 20 feet above the ground. He said the airplane was configured with 20 degrees of flaps, and the airspeed was about 45 mph. The pilot indicated the left wing stalled, and the airplane descended, colliding with the surface of the lake. The airplane received structural damage to the left wing, fuselage, and landing gear. On the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the pilot, the pilot described the weather conditions as clear, visibility unlimited, a temperature of about 15 degrees F, light and variable winds, with no gusts. He also indicated that he observed several wind shifts after the accident.