St. Michael, AK, USA
N5955X
BRANTLY B2
The pilot reported that, while in a high-hover profile conducting aerial reindeer herding operations, he decided to make a precautionary landing with the skid-equipped helicopter on "knee-high" tussocks in remote tundra due to several "left yaw movements" followed by an "uncommanded left yaw." The pilot initiated a hovering autorotation from about 15 ft above ground level. During the landing sequence, the left skid assembly was damaged, and the helicopter settled forward and to the left, which resulted in the three main rotor blades impacting the tundra. All three main rotor blades separated midspan due to the impact, and the helicopter sustained substantial damage to the main rotor system and fuselage. After the accident, the pilot spoke with a witness who heard the engine producing "popping" noises and then "quit." At the time of the accident, the pilot reported he did not realize that the engine had lost power. Postaccident examination of the airframe and engine by the pilot revealed no preimpact mechanical malfunctions that would have precluded normal operation. While inspecting the fuel cell, the pilot found 1/8 of a cup of water with about 5 gallons of fuel remaining. During the aerial herding operations, the helicopter was shut down for refueling several times throughout the day, and no hot refueling operations were conducted. The pilot spoke with some local community members who were assisting him on the day of the aerial herding operations. The pilot found that, when the helicopter was last refueled before the accident flight and when the fuel was transferred from a steel drum with a pump system to a plastic jug for pouring in the helicopter, a water separating filter/funnel was not used by one of the local community members who was assisting the pilot with the refueling operations. The individual misunderstood the refueling operations and thought that the fuel filtering process would take place as the fuel was poured directly into the helicopter. Water was subsequently found in the steel drum that was used. The pilot reported that he conducted a preflight check of the helicopter's fuel cell (sump) before the accident flight, and no fuel discrepancies were observed at the time. The Federal Aviation Administration published Advisory Circular 20-125, "Water in Aviation Fuels," which discussed the potential hazards of water in aviation fuels and stated, in part: The pilot in command has the final responsibility to determine that the aircraft is properly serviced. The pilot in command should also be present during the refueling operation to inspect a sample of the fuel from the dispensing unit prior to fueling the aircraft. Refueling from drum storage or cans should be considered as an unsatisfactory operation and one to be avoided whenever possible. All containers of this type should be regarded with suspicion and the contents carefully inspected, identified, and checked for water and other contamination.
The pilot reported that while in a high hover profile conducting aerial reindeer herding operations, he decided to make a precautionary landing with the skid-equipped helicopter on "knee-high" tussocks in remote tundra due to several "left yaw movements" followed by an "uncommanded left yaw." The pilot initiated a hovering autorotation from about 15 feet above ground level. During the landing sequence, the left skid assembly became damaged, the helicopter settled forward and to the left, which resulted in the three main rotor blades impacting the tundra. All three main rotor blades separated mid-span due to the impact, and the helicopter sustained substantial damage to the main rotor system and to the fuselage. After the accident, the pilot spoke with a witness who heard the engine produce "popping" noises and then "quit." At the time of the accident, the pilot reported he didn't realize the engine lost power. A postaccident examination of the airframe and engine by the pilot revealed no preimpact mechanical malfunctions with the airframe or engine that would have precluded normal operation. While inspecting the fuel cell, the pilot found 1/8th of a cup of water with about 5 gallons of fuel remaining. During the aerial herding operations, the helicopter was shut down for refueling several times throughout the day and no hot refueling operations were conducted. The pilot spoke with some local community members who were assisting him on the day of the aerial herding operations. The pilot discovered that when the helicopter was last refueled before the accident flight, when the fuel was transferred from a steel drum with a pump system to a plastic jug for pouring in the helicopter, a water separating filter/funnel was not utilized by one of the local community members who was assisting the pilot with the refueling operations. The individual misunderstood the refueling operations and thought that the fuel filtering process would take place as the fuel was poured directly into the helicopter. Water was subsequently found in the steel drum that was utilized. The pilot reported he conducted a preflight check of the helicopter's fuel cell (sump) before the accident flight and no fuel discrepancies were observed at the time. The pilot reported that the helicopter did not have tundra boards installed on the skids at the time of the accident and that based upon his research, there were no commercial companies that manufactured supplemental type certificate (STC) tundra boards for the Brantly B-2B helicopter. He added that he felt uncomfortable creating his own tundra boards via a Federal Aviation Administration (FAA) field approval process since he doesn't have an engineering background. The pilot reported that having tundra boards installed on the skids of the helicopter would be beneficial from a safety aspect while conducting landings on tundra terrain, since tundra boards would help distribute the load of the helicopter and could help prevent the skids from moving or getting stuck. The pilot further reported that if the hovering autorotation was conducted with tundra boards installed, the left skid assembly would have remained intact due to the distributing of the load across a larger surface area. A review by the FAA Rotorcraft Standards Staff did not find any approved or in-work STC that would modify the Brantly B-2B skids with snow boards, tundra boards, slump pads, or any similar device at the time of the accident. The accident helicopter was not equipped, nor was it required to be equipped with an emergency locator transmitter. The FAA has published Advisory Circular 20-125 Water in Aviation Fuels (1985). This document discusses the potential hazards of water in aviation fuels and states in part: The pilot in command has the final responsibility to determine that the aircraft is properly serviced. The pilot in command should also be present during the refueling operation to inspect a sample of the fuel from the dispensing unit prior to fueling the aircraft. Refueling from drum storage or cans should be considered as an unsatisfactory operation and one to be avoided whenever possible. All containers of this type should be regarded with suspicion and the contents carefully inspected, identified, and checked for water and other contamination.
The pilot’s inadequate supervision of the refueling process, which resulted in a loss of engine power due to water contamination in the helicopter’s fuel system from the fuel drum and subsequent impact with terrain.
Source: NTSB Aviation Accident Database
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