On September 24 2016, at about 1015 PM EDT, Commutair flight 4919, a De Havilland Dash 8-200, N366PH, performed a nose gear up landing on runway 1R after the nose gear would not fully extend during approach to Washington Dulles International Airport (KIAD), Dulles, Virginia. The passengers were evacuated via exit doors on the runway. There were no injuries to the 21 passengers and 3 crew members and the airplane sustained substantial damage. The flight was operating under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from Albany International Airport (KALB), Albany, New York to KIAD. According to the operator, the airplane was scheduled for maintenance during an overnight period on the evening before the accident flight at the Albany Maintenance Hangar Facility at KALB. As part of the scheduled maintenance, a frangible towing fuse in the nose landing gear mechanism was removed and replaced. The aircraft was released from maintenance and signed off for revenue service on the morning of the accident flight. According to the flight crew, the flight was uneventful until the final approach phase when they were configuring the airplane for landing at KIAD. After selecting the gear down, both main landing gear indicated down and locked but the nose gear indicated that the gear doors remained open and that the gear was unsafe. The flight crew then retracted the main landing gear and climbed to 3000 feet. While at altitude, the flight crew attempted to lower the gear a second time but the same result was indicated. The flight crew then performed the manual gear extension, but the nose gear still failed to extend. The flight conducted a low pass of the airport and ground personnel confirmed that the main landing gear were down, but the nose gear was retracted with the doors open. The flight crew climbed back to 3,000 feet, declared an emergency and requested airport emergency vehicles standby. During the landing roll, the nose of the airplane contacted the runway surface and the captain shut down the engines after the airplane came to a stop and called for an evacuation. None of the passengers or crew were injured. Examination of the airplane found substantial damage to the airplane skin and forward pressure vessel as a result of the contact with the runway. Inspection of the nose gear system found that the frangible towing fuse, which was replaced before the flight, was incorrectly installed.