On October 15, 1996, at 0300 hours mountain standard time, an Aero Commander 690, N15VZ, collided with the runway surface after the landing gear collapsed on runway 26R at the Sky Harbor International Airport, Phoenix, Arizona. The airplane sustained substantial damage. The airline transport pilot, two flight nurses, and one patient were not injured. The airplane was being operated by Sun West Aviation, Inc., Ogden, Utah, as an air medical transport flight under 14 CFR Part 135 when the accident occurred. The flight originated from Show Low, Arizona, at 0158. Visual meteorological conditions prevailed at the time and a company VFR flight plan was filed. The pilot reported a hydraulic failure 35 miles east of Phoenix. He indicated the landing gear in transit light stayed illuminated and he was unable to get the landing gear to lock using the emergency extension procedure. The landing gear collapsed during touchdown and the airplane slid to a stop. The damage to the plane was limited to the belly area of the fuselage. The airplane was examined by the Federal Aviation Administration (FAA) and was found to have an hydraulic fluid leak at a hose attachment fitting to the right main landing gear brake system. Examination of the fitting revealed the hydraulic line had fractured at the flare joint in the fitting. On November 21, 1996, the landing system was functionally checked after the leak had been repaired. The check included testing of the emergency extension procedure. According to the FAA there were no defects noted with the airplane's landing gear system.