On April 9, 2005, about 1100 Pacific daylight time, the landing gear of a Piper PA-24-250, N7737P, collapsed during the landing rollout at the California City Municipal Airport, California City, California. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The flight departed from Lake Havasu, Arizona, about 1000 mountain standard time, en route to Porterville Municipal Airport, Porterville, California. No flight plan had been filed. In a written statement, the pilot reported that he initially departed Deming, New Mexico. He obtained a weather briefing, and was informed of high winds, but no clouds en route. He made a fuel stop at Lake Havasu City. He then called for another weather briefing, and was informed of high winds and turbulence with scattered clouds at his destination. He elected to continue the final leg of the flight. En route, the pilot encountered turbulence, and climbed to 10,500 feet. As he crossed the Sierra Nevada Mountains at Tehachapi, he observed an overcast layer over the San Joaquin Valley. Not being IFR rated, he decided to divert back to California City. During the descent, he encountered heavy turbulence. On downwind, he activated the landing gear, but it failed to extend, giving neither an up-or-down indication. He observed the landing gear circuit breaker had popped out, and attempted to reset it, but it would immediately pop back out. He then activated the emergency gear extension system. After extending the gear, he stated, "I pulled on the handle and felt it was locked." On approach, the pilot experienced strong crosswinds and turbulence, and just after touchdown, the landing gear collapsed. The airplane skidded approximately 200 feet along the runway. This was upgraded from an incident to an accident on June 13, 2005. A Federal Aviation Administration inspector noted that the structural members on the bottom of the cabin had sustained damage.