Aircraft Accident/Incident Report

Thorne Bay, Alaska 99901
Wednesday, July 24, 2013 11:40 AKD

On July 24, 2013, about 1140 Alaska daylight time, a float-equipped de Havilland DHC-2, N4787C, collided with trees following a loss of engine power near Lake Galea, about 15 miles northwest of Thorne Bay, Alaska, on Prince of Wales Island. The airline transport pilot and two passengers sustained serious injuries, one passenger sustained minor injuries, and the airplane sustained substantial damage. The on-demand air taxi flight was operated by Promech Air, LLC, under the provisions of 14 Code of Federal Regulations (CFR) Part 135 with a company visual flight rules flight plan filed. Visual meteorological conditions prevailed. The flight departed Ketchikan Harbor Seaplane Base (5KE), Ketchikan, Alaska, at 1100 and was destined for Shipley Bay, Alaska. According to the pilot, the airplane was in cruise flight at an altitude of about 1,500 feet above mean sea level (msl), which he estimated was about 1,200 feet above ground level (agl) in the area over which he was flying, when he heard a loud "boom" and a series of loud and continuous "pop-pop-pop" noises. The pilot said that he reported on the company radio that he had lost an engine cylinder and was going to land. The pilot said that everything was shaking and that he did an immediate 180-degree turn to land on the lake that he had just overflown. The pilot stated that, as he turned the airplane on a base leg for the lake, he put in two pumps of flaps, and, about that time, the engine lost power completely. The pilot estimated that the amount of time that elapsed from when he first heard the loud "boom" to the time that the engine lost power completely was less than 1 minute. The pilot stated that, once the engine lost power completely, the airplane was soon colliding with trees. According to the operator, the airplane was located in a wooded area about 300 yards from the lake. The pilot stated that he and two passengers were able to exit the airplane but the passenger in the right seat was unable to exit the airplane until more help arrived to assist. The pilot located the airplane's 406-MHz emergency locator transmitter and flipped the switch to the "on" position to be sure that it was transmitting. According to the operator, the Rescue Coordination Center telephoned the operator and provided coordinates for the downed airplane. The pilot also located the airplane's survival kit, and he and a passenger positioned a piece of wing wreckage in a marsh area to try to make the accident site visible to overflying aircraft. The pilot established cellular telephone contact with the operator, which had dispatched another company airplane to assist. The pilot said that he heard the other company airplane approaching and used a flare from the survival kit to signal his location. The other company airplane landed on Lake Galea, and company personnel hiked to the accident site to assist the pilot and passengers. A U.S. Coast Guard (USCG) helicopter from Air Station Sitka soon arrived. The USCG transported the pilot and all three passengers from the scene two at a time. Aircraft recovery personnel who retrieved the wreckage reported that engine cylinder separation damage was visible. Engine components have been retained for further examination. According to the operator, the Pratt & Whitney R-985-AN-14B engine had accumulated 31 hours since major overhaul.

Not Yet Reported