On June 2, 2011, about 1300 mountain standard time, a Piper PA-46-310P, N712MK, experienced a landing gear extension system failure during approach to the Lake Havasu City Airport, Lake Havasu City, Arizona. The airplane was substantially damaged as it slid to a stop on the runway. Neither the airline transport pilot nor passenger was injured. The airplane was registered to Sea Air Holdings, LLC. The personal flight was operated under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and an instrument flight plan was filed. The flight originated from Portland, Oregon, about 0830. The pilot said that he was descending into the traffic pattern after canceling his IFR clearance and he attempted to lower the landing gear. There was no response. At that point he reset the landing gear circuit breaker and tried again to no avail. He then went to the emergency check list and attempted to drop the gear. Again there was no response. He continued to repeat all procedures for approximately the next 1 1/2 hours until he was at minimum fuel and was forced to land gear up. Prior to landing he located his passenger in the right rear seat, secured all items in the cabin, feathered and shut down the engine, and all electrical and fuel controls. The aircraft touched down at mid field and slid about 1200 feet. Examination of the airframe revealed that a lower fuselage bulkhead was ground down. A Federal Aviaiton Administration (FAA) airworthiness inspector examined the airplane's landing gear system following recovery from the runway. The aircraft was placed on jacks and electrical power was supplied to the airplane. Both the normal and emergency extension landing gear systems did not work. The landing gear was lowered by bleeding pressure out of gear up line fitting on the nose gear sequence valve. The Emergency Gear Release valve, P/N 85124-02, was manually operated at the valve. Its control arm would only move 1/4-inch instead of the approximately 2 inches of movement it should have. It would not port fluid from the gear down line to the gear up line, which is its required function to allow hydraulic fluid to return through the up line to the reservoir and allowing gravity to extend the gear. The cause of the failure of the normal gear extension system was traced to a faulty low pressure switch.