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N18FH accident description

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Tail numberN18FH
Accident dateAugust 20, 1997
Aircraft typeBell BH-206B
LocationDillingham, AK
Additional details: None

NTSB description

HISTORY OF FLIGHT

On August 20, 1997, at 2010 Alaska daylight time, a Bell BH-206B helicopter, N18FH, was destroyed when it impacted steep terrain about 2,000 feet msl on Kemuk Mountain, 42 nautical miles north of Dillingham, Alaska, at position 59-41.5 degrees north latitude, 158-00.0 degrees west longitude. The commercial certificated pilot sustained fatal injuries. The three passengers sustained serious injuries. The U. S. Government flight was conducted under 14 CFR Part 135 to transport three Federal Aviation Administration technicians installing a radio relay site on the top of Kemuk Mountain. The flight departed the mountaintop site for Dillingham at 2000.

The helicopter and work crew arrived at the relay site about 1600. As they were landing, the crew leader informed the pilot that they had chosen a walk-off route to lower terrain in case the weather deteriorated. After landing, he discussed this option with the pilot, suggesting that the pilot relocate to a lower area, and the crew would walk down if necessary. The pilot said he would stay at the site.

The mountaintop takeoff and landing site included a fiberglass hut for communications equipment, an antenna, a wind sock, and a large, portable survival shelter. The shelter was equipped with a stove and heater. The crew had placed their survival gear, sleeping bags, and food, in the hut. During the period between landing and departure, the pilot stayed in the shelter.

The passengers told the NTSB investigator that they boarded the helicopter in preparation for the flight to Dillingham about 2000. They said they all were wet when they boarded the helicopter, that the windows were fogging up, and they all were focused on getting warm and dry. The passenger seated in the left, front seat said that he had to get out of the helicopter before takeoff, and wipe off the pilot's window so that the pilot could see. After getting back into his seat, he left his shoulder harness disconnected in order to wipe fog off the interior windows for the pilot. The aft right seat passenger stated he placed his arm out his window in order to hold the pilot's door open, so the pilot could look down to keep sight of the ground.

The passengers said they planned to hover down the mountain until clear of the clouds. They told the NTSB investigator that they suggested the pilot fly down the "walk off" route, as this was into the wind, a gentle slope, and free of obstructions. After beginning to hover down the mountain, the pilot said that it was not going to work, and he was going to try to go back up. All passengers stated that horizontal visibility was near zero, and that they only saw terrain ahead of them immediately prior to impact. The passenger on the pilot side (right) of the helicopter stated that he lost vertical visual contact with the ground, and then saw a ridge coming up in front of them. The helicopter impacted terrain, continued forward across a ridge, and rolled down the other side.

INJURIES TO PERSONS

The pilot's seat was equipped with a shoulder harness. The passengers said he intentionally did not put it on so that he could lean to the right and look down through his open door in an attempt to see the ground. The passenger who was ejected said he witnessed the pilot's torso repeatedly being thrown outside the helicopter, and then rolled on by the helicopter, as it traveled down the slope.

The passengers stated that the pilot was initially conscious, but died within the first hour.

The left, front seat passenger was provided with a shoulder harness. He intentionally left it off in order to reach the inside of the pilot's window and wipe it clean of fog. This passenger sustained serious injuries.

The left, aft seat passenger, was provided with a lap belt only. He remained restrained in the helicopter. He sustained serious injuries.

The aft, right seat passenger was provided with and wearing a lap belt only. He was ejected from the helicopter, and observed it rolling several times before coming to rest. He stated that when he was ejected, he landed in a patch of mossy tundra. He sustained serious injuries. The attachment fitting of his seatbelt was found separated, with the buckle clasped.

PERSONNEL INFORMATION

The commercial pilot held rotorcraft-helicopter, instrument-airplane and helicopter, and airplane-single engine land ratings.

He held a valid second class medical certificate, issued on April 2, 1997, with the restriction that he "shall wear corrective lenses for distant vision, and possess lenses for near vision." The survivors stated the pilot was wearing his glasses at the time of the accident.

The pilot began his employment with the operator on June 21, 1996. At the time of the accident he was qualified with the company as a pilot-in-command on the BH-205, and the BH-206. His most recent competency check was completed under 14 CFR 135.293 on May 9, 1997, in the BH-205. He completed his initial competency check with the company in the BH-206 on May 1, 1997. Both flight examinations were conducted by the company check airman. A requirement during these checks was to perform basic helicopter control maneuvers under simulated instrument conditions.

Records provided by the company indicated that he had accumulated approximately 13,400 hours of total flight experience, with approximately 10,000 hours as a pilot-in-command of helicopters. 4,000 hours were in the BH-206.

The company reported that the pilot had flown 208 hours in the previous 90 days, and 60 hours in the last 30 days, 4 of which were in the BH-206.

The passengers said the pilot went to bed early the night prior to the accident, and was up for breakfast by 0600. The FAA Flight Service Station specialist on duty in Dillingham described him as "hanging around the Flight Service Station all day, lying on the couch, and waiting for weather to improve."

After arriving at the work site on Kemuk Mountain, the passengers said that the pilot stayed in the survival shelter while they worked. At 1930 the pilot asked the crew how much longer they required. They told him about 30 minutes. He replied that was fine, since their flight plan was going to expire at 2030. They said he seemed to have no real sense of urgency.

The three passengers were employees of the Federal Aviation Administration, Alaskan Region, Airways Facilities Division, National Airspace Implementation Branch.

The crew leader had been employed by the FAA for 22 years. He had installed numerous remote communications sites throughout Alaska, and was in charge of the installation field teams.

The left front seat passenger was an electronics technician for the FAA. He was a certificated airframe and powerplant mechanic.

The left rear seat passenger was a maintenance technician for the FAA. He had been a student pilot, but did not complete his pilot certification. This was his first "high site" installation project.

AIRCRAFT INFORMATION

The skid equipped helicopter was owned by Evergreen Equity, Inc., of McMinnville, Oregon. It was operated by Evergreen Helicopters of Alaska, Inc., of Anchorage, Alaska, a subsidiary of Evergreen International, Inc., of McMinnville, Oregon.

Evergreen Helicopters of Alaska, Inc., operated a fleet of six airplanes and six helicopters. The Principal Base of Operations is Merrill Field, Anchorage. The airplanes operate on a contract basis worldwide, and the helicopters operate on contracts throughout Alaska. Helicopter line stations are maintained in Kenai and Nome, Alaska.

The operator began flying the helicopter in Alaska in May of 1997. A cabin heater and defog kit which utilized hot bleed air from the engine had been partially installed as per STC# SH3887NM on June 17, 1997. The plumbing and blowers to provide hot bleed air from the engine to the floor outlets were installed. The ducting to transport hot air to the windshield defog diffusers was on order but not yet received by the operator.

The helicopter did not have a functioning windshield hot air defog system. Windshield defog fans were installed in the instrument panel to circulate cabin air. The fan motors were tested after the accident and operated normally.

The Flight Manual Supplement for the cabin heating system specified that heater use was allowed during takeoff, hover, or landing for aircraft equipped with the C-20B engine installed in the accident helicopter.

None of the passengers remembered hearing a fan or loud blower noise.

The helicopter was authorized by the FAA to operate in VFR conditions only. The helicopter had the following equipment installed:

Attitude Gyro Directional Gyro Turn Needle/Turn Coordinator Airspeed Vertical Speed

METEOROLOGICAL INFORMATION

On the day of the accident, the pilot arrived at the FAA Flight Service Station in Dillingham at 0800. He remained there until 1520, when he filed a VFR flight plan and departed. During this time both he and the passenger crew leader received numerous updates of weather information.

The Terminal Forecast for Dillingham for the period 1000 to 2200 was 500 feet overcast, 6 miles visibility in light rain, with temporary conditions of 500 feet scattered, 1,200 feet overcast with visibility of 3 miles in light rain and fog.

The coastal Area Forecast for the period 1200 to 2400 was for ceilings of 500 feet scattered, 1,500 feet broken, and 3,000 feet overcast with 3 miles visibility in light rain and fog.

The inland Area Forecast for this period called for 1,500 feet scattered, 3,000 feet broken, 4,000 feet overcast. Temporary conditions of 1,500 feet broken, with visibility 3 miles in light rain and fog, were forecast.

The passengers said that there was no difficulty with weather on the way to Kemuk Mountain. They indicated that the weather deteriorated about two hours before they attempted to leave Kemuk Mountain, with the cloud bases somewhere below their altitude.

All three survivors described the weather as visibility near zero, with the 2,350 feet msl takeoff and landing site shrouded in clouds, with rain blowing horizontally, and winds from 30 to 50 knots.

COMMUNICATIONS

Radio communications were not possible between the Kemuk Mountain takeoff site and the Dillingham airport. The last communication received from the accident helicopter was on the initial departure from Dillingham.

The passengers stated that after the accident, their attempts to communicate on a handheld radio utilizing the emergency frequency 121.5 Mhz, were masked by the helicopter's Emergency Locator Transmitter (ELT) signal on the same frequency. Their attempts to contact passing aircraft on other frequencies were unsuccessful. They stated they were unsure of the Air Route Traffic Control Center frequencies used in the area.

WRECKAGE AND IMPACT INFORMATION

The wreckage was examined by the NTSB investigator at the accident site on August 22, 1997. Impact marks were located on the southwest side of a ridge, about 30 feet below an approximate 2,000 feet msl saddle. Portions of both the left and right skids were located at this location. A debris trail extended in a northeast direction, about 85 feet through a saddle on the ridge, and approximately 170 feet down the rocky incline on the northeast side of the ridge. This northeast slope was approximately 40 degrees from horizontal.

The debris trail consisted of both skids, the windshields, both tail rotor blades, both main rotor blades, the main rotor head, and the tail boom. At the end of the debris trail were the main fuselage and cabin section, with the engine and main transmission attached. No indications of any preimpact mechanical anomalies were discovered.

The upper cabin section exhibited deformation toward the left side. All the windows were missing.

All seatbelt and harness attachments remained attached to the airframe, except for the right side, aft passenger seat, inboard fitting. This triangular shaped belt attach fitting was separated in two locations. The belt buckle was found connected. The fitting was retained and examined at the NTSB metallurgical laboratory in Washington, DC.

The left and right side fresh air vents were in the closed position.

The "Arctic Heater" control knob under the pilot's seat was in the full "Off" position.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 5700 E. Tudor Road, Anchorage, Alaska, on August 22, 1997. The cause of death was attributed to blunt trauma injuries to the chest, as a consequence of crushing, not deceleration.

A toxicological screening was performed on samples drawn from the pilot. The only remarkable finding was 3.0 mg/dL Acetone detected in urine. Research by the NTSB Medical Officer indicates that this is a low level quantity, likely the result of normal metabolism.

A review of the pilot's FAA and National Guard medical records revealed no anomalies.

SURVIVAL ASPECTS

The survivors left all their survival equipment and sleeping bags in the survival shelter located at the work site. They discussed attempting to make their way back to the shelter, but decided to remain with the helicopter because they did not know where they were due to the fog and low visibility.

They tied the hull of the helicopter to rocks so that it would not slide, then climbed inside. They blocked the openings with cushions, and used space blankets for further protection from the wind and rain. On the morning of August 21, they burned fuel from the helicopter's tank in a coffee can for heat.

The survivors described the weather at the time of the accident, and through the night, as "really sour, very wet and windy," deteriorating to constant rain, winds of 30 to 50 knots, and temperature near 40 degrees F.

They all said the space blankets did not hold up well, and shredded in the wind. One survivor was wearing "polar fleece" and a knit hat, which he said kept him fairly comfortable. A second survivor stated he was wearing cotton long johns and jeans, and that these were cold after becoming wet.

The aft left seat passenger stated that nine months before the accident he attended the FAA locally contracted survival school. He stated that the lessons learned assisted him after the accident.

The helicopter's ELT signal was received by the Alaskan Rescue Coordination Center at 2159, and a search commenced. At 0056 on August 21, a Coast Guard C-130 confirmed an ELT at Kemuk Mountain, but could not see the survivors due to low ceilings.

The survivors left the ELT on continuously, except when they attempted voice broadcasts on 121.5 MHz. They stated that when they heard airplanes overhead, they also turned it on and off to simulate Morse code, in an attempt to let rescuers know they were alive. Search Rescue Units attempting to locate the ELT reported that the intermittent signal complicated efforts to determine the exact crash location.

At 0822 on August 21, the pilot of a volunteer DHC-2 airplane reported observing a flare come out of the clouds at Kemuk Mountain.

Weather prevented rescue of the survivors until 1350 on August 21.

TESTS AND RESEARCH

The right, aft, seatbelt inboard attachment was examined at the NTSB Metallurgical Laboratory. This component was manufactured by Davis Aircraft products of Northport, NY.

One of the two fracture locations revealed indications of overstress, and the other exhibited preexisting exfoliation corrosion. This fitting is manufactured from 2024-T3 aluminum. According to the NTSB metallurgical laboratory report, T3 and T4 tempered 2000 series aluminum alloys are susceptible to this type corrosion.

Prior to the date of the accident, the manufacturer converted from aluminum alloys to steel alloys in the production of this fitting. The only maintenance required on this component is for visual condition performed during 100 hour inspections.

ADDITIONAL INFORMATION

The company Operations Manual, paragraph 929, states "Crew members will keep seat belt and shoulder harness fastened at all times..."

14 CFR 135.171(b) states "Each flight crewmember oc

(c) 2009-2011 Lee C. Baker. For informational purposes only.