On February 12, 1994, at 1020 mountain standard time, a Cessna 402C, N812AN, collided with another Cessna 402C, N26514, while taxiing for departure at the Grand Canyon National Park airport, Grand Canyon, Arizona. N812AN was operated by Air Nevada Airlines, Inc., of Las Vegas, Nevada, and was on a positioning flight under the provisions of 14 CFR Part 91 of the Federal Aviation Regulations. N26514 was operated by Air Vegas, Inc., also of Las Vegas, and was on a 14 CFR 91 positioning flight. Both aircraft sustained substantial damage. The occupants of both aircraft consisted of their respective flight crews, and no injuries were sustained. N812AN, operating as Air Nevada flight 12, was originating as a company positioning flight to McCarran International airport, Las Vegas, Nevada. N26514, operating as Air Vegas flight 14, was originating as a company positioning flight to Henderson airport, Las Vegas, Nevada. According to air to ground communications tapes at the Grand Canyon Air Traffic Control Tower, Air Vegas 14 reported ready for taxi to takeoff at 1016:30. The flight was given a taxi clearance at 1016:39 to runway 3. Air Nevada 12 reported ready for taxi to takeoff at 1017:10, and was subsequently cleared to taxi to runway 3. Both aircraft reported the collision to the ground controller about 1021:30. In a telephone interview, the flight crew of N26514 reported that they taxied to the end of the runway and stopped at the hold short line. Both pilots stated that about 1 minute later they felt a large jolt from behind and their aircraft was moved forward about 20 feet. The pilot of N812AN stated that as she approached the rear of the Air Vegas aircraft the brakes were applied to stop the aircraft. The pilot reported that brake pedal application had no effect on the speed of the aircraft, and just before contacting the other aircraft, both mixtures were pulled to idle cutoff. The pilot was unsuccessful in stopping the aircraft prior to colliding with the tail of N26514. Air Vegas personnel reported that the damage sustained by N26514 consisted of propeller slashes to the horizontal and vertical stabilizers, elevator, and rear fuselage. The entire fuselage was also reported to have been deformed. Air Nevada personnel reported that N812AN sustained damage to the propeller blades, cowlings, windshields, and aircraft nose. The maintenance department examined the brake system and reported finding no irregularities in the system operation. The company pilot who flew N812AN in revenue line operations on February 11 reported that he experienced a fading of the left brake pedal during landing. The pilot said that after reapplication of the brake pedal, the problem did not repeat itself. The brake system of N812AN was examined by a Federal Aviation Administration (FAA) A & P mechanic on the day of the accident. In his written report, the mechanic stated that the left brake master cylinder was faulty and noted: "Under hard braking forces applied by the pilot, the left brake operated normally hold pressure continuously. However, under less forceful brake application, such as that incurred during taxi, the pedal would gradually sink to the bottom of its travel preventing the pressurization of the left brake system."