On December 28, 2000, about 1515 Pacific standard time, a Grumman G-44, N69058, registered to Ag Northwest Inc., and operated by a commercial pilot as a 14 CFR Part 91 personal flight, collided with the terrain following a landing gear collapse while landing at Hermiston Municipal airport, Hermiston, Oregon. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft was substantially damaged and the commerical pilot and his passenger were not injured. The flight departed from McMinnville, Oregon, about one hour and 15 minutes prior to the accident. In a written statement, the pilot reported that the flight was uneventful until he lowered the landing gear. When power was reduced below 15 inches of manifold pressure, the pilot observed the gear unsafe light (red) was illuminated. Several unsuccessful attempts were made to either extend or retract the landing gear both mechanically and manually. After all attempts were exhausted, and because of deteriorating light conditions, the pilot secured the cabin, moved the passenger to an aft seat, and initiated a landing to the grass area between the runway and taxiway. When the aircraft touched down, the partially extended landing gear collapsed, and the aircraft slid on its belly. As the aircraft slowed, the keel caught on a berm and the aircraft started to turn. The left wing contacted the ground which damaged the wing spar. Inspection of the landing gear revealed that three out of the four snap rings holding the pistons for the landing gear actuators failed. The snap rings are "on condition" items and were last returned to service in 1991.