On July 3, 2009, approximately 0540 mountain daylight time, a Cessna 441, N988AE, owned and operated by Air Evac Services Incorporated, was substantially damaged following an intentional gear-up landing at Albuquerque International Sunport (KABQ), Albuquerque, New Mexico. The repositioning flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91 with an instrument flight plan. Night visual meteorological conditions prevailed. The airline transport pilot and two crew members were not injured. The flight departed the Double Eagle II Airport (KAEG), Albuquerque, New Mexico, at 0320. According to a statement provided by the pilot, the flight was dispatched to pick up a trauma patient in Socorro, New Mexico. While en route, thunderstorms developed along the intended route of flight, so the pilot decided to return to KAEG. While on final approach to KAEG, the gear down position was selected and the landing gear circuit breaker popped. After one minute, the pilot reset the circuit breaker and again the circuit breaker popped. After putting the landing gear handle up, the circuit breaker would remain reset until the landing gear handle was selected down. The pilot initiated the "Landing Gear Will Not Extend Normally" checklist. After activating the nitrogen blowdown bottle, the crew heard the nitrogen flow but the landing gear did not extend. The pilot attempted to maneuver the airplane in an attempt to lower the landing gear. Despite troubleshooting the malfunction, the gear was confirmed in the retracted position by another pilot utilizing night vision goggles during a low approach at KAEG. The pilot elected to land gear up utilizing runway 03 at KABQ. During the landing flare, the pilot shut off both engines, and the airplane settled on to the runway. The airplane slid to the right side of the runway and came to a stop. An inspection of the airplane revealed substantial damage to the fuselage. After recovering the airplane, an examination of the airplane was conducted under the supervision of a Federal Aviation Administration inspector. A fitting was found loose on the nitrogen bottle distribution system resulting in a failure of the emergency extension system. A review of maintenance records indicated that maintenance was performed in the are of the loose fitting in July 2008. A gear extension and retraction tested was performed and no anomalies were detected. However, addition testing on the landing gear selector switch, performed by the operator at a later time, replicated the popped circuit breaker condition, when the landing gear down position was selected.