History of Flight
On December 19, 2010, about 1000 central standard time, a Eurocopter AS350-B2 helicopter, registration N549AM, sustained substantial damage when it landed hard after a loss of power during takeoff from a helipad at La Monte, Missouri. The pilot, flight nurse, and flight paramedic received serious injuries. The helicopter was operated by Air Methods Corporation under 14 CFR Part 91 as a medical flight, departing for an on-scene patient transfer at Fristo, Missouri. Visual meteorological conditions prevailed, and the flight was on a company visual flight rules flight plan.
The pilot arrived about 0645 for his shift starting at 0700. He performed preflight planning including a weather check, crew brief, and preflight inspection. He checked the air filter for ice and snow and reported no visible moisture on the helicopter. The first EMS flight departed about 0724, arrived at the patient location in Lincoln, Missouri, at 0737, and departed with the patient about 0800. The helicopter arrived in Columbia, Missouri, about 0827, where the pilot fueled with 60 gallons of Jet A fuel. The return flight to La Monte departed about 0906 and arrived about 0934. After landing, the crew completed paperwork. No rain or snow showers were encountered during these flights.
The pilot was notified of a second EMS mission about 0948. After a weather check, the crew boarded. The pilot started and took off without incident. He lifted straight up to about 100 to 125 feet, then applied left pedal to point southeast. As he completed the pedal turn, he heard a loud "bang." He lowered the collective and turned right to return to the helipad. He flared and pulled up on the collective. The helicopter hit hard on the helipad, spreading the skids and causing the helicopter to rest on its belly. The fuel tank ruptured. A small flame appeared but extinguished quickly. The pilot turned off the main electrical push button and yelled for the crew to exit. A first responder later turned off the "DC Bat" button. The flight nurse in the right rear seat reported that the engine went quiet after liftoff to about 100 feet; she heard no loud noise. The pilot yelled "Brace yourself." She assumed the crash position and experienced extreme pain after impact. She refused assistance until medical personnel arrived and placed her on a long board. She called her husband and the EMS communication specialist at about 1000. The flight paramedic in the left rear seat reported that the engine stopped making noise above tree top level. She braced for impact, which caused all doors to open. Fuel was on the ground. She saw sparks from skids hitting concrete but no flames. She could not walk and needed assistance from a first responder.
Personnel Information
The pilot, age 53, held an airline transport pilot certificate with helicopter and instrument ratings, and a second-class medical certificate issued March 3, 2010. He had about 7,928 total helicopter hours, including about 296 hours in the AS350-B2. In the preceding 90 days, he flew 34 hours; in the last 30 days, 9 hours. His most recent 14 CFR Part 135 competency/proficiency check was on August 5, 2010.
Aircraft Information
The Eurocopter AS350-B2, serial number 4339, manufactured in 2007, had a three-blade main rotor, conventional tail rotor, skid landing gear, and a single 625 shaft horsepower Turbomeca Arriel 1D1 free turbine engine. It was equipped with an Air Methods EMS interior configured for one patient on a litter and two medical crew. The flight manual listed maximum gross weight as 4,960 pounds. At the time, the helicopter was fueled to 60 percent and within weight and balance limits.
Maintenance records showed 1,288 total hours. The most recent inspection on December 17, 2010, included 50-hour, 100-hour, and 600-hour inspections. No tasks required inspecting the main airframe fuel filter or Le Bozec fuel filter assembly. The fuel filter cartridge was replaced during the 1,000-hour inspection at 1,008 hours, about 280 hours before the accident.
Meteorological Information
At 0953, Sedalia Regional Airport (10 nautical miles east) reported wind from 170 degrees at 5 knots, 7 miles visibility, overcast at 3,200 feet, temperature 3°C, dew point -3°C, altimeter 30.08 inches of mercury. The pilot reported snow showers in the forecast but actual weather better. No moisture, snow, or ice was on the helicopter or FDC Aerofilter during preflight.
Helipad Information
The helipad, 30 feet by 30 feet concrete, located at 200 West Front Street, La Monte, Missouri, had orange balls marking wires but no red lights for light poles, wires, or trees. No lights bordered the touchdown and lift-off area. A 3,000-gallon aboveground fuel tank sat about 35 feet from the pad. A windsock was present but not lighted. There was no approach and takeoff path, requiring high-out-of-ground-effect hover for takeoffs and landings. No safety area extended beyond the final approach and takeoff area.
Wreckage and Impact Information
The helicopter came to rest upright on a westerly heading. The fuel flow control lever was in the flight detent, with full range of travel confirmed. The fuel shutoff lever was forward and lock-wired open. Hydraulic cut-off switch was forward and guarded. Fuel pump switches were on. Flight control continuity was confirmed from controls to input mechanisms, though full cyclic and collective movement was limited by impact damage. The main transmission rotated freely with tail rotor rotation. The engine-to-main transmission drive shaft was intact. Main rotor blades showed no obvious impact damage. Tailboom was intact. Lower vertical fin crushed and bent right. Tail rotor drive system intact; tail rotor blades showed impact and flapping damage. Both skids separated from cross tubes above attachment points, consistent with high vertical velocity impact. Fuel tank compromised. Fuel present in lines and filter, filter clean, bypass button not extended.
Engine rotated freely with no visible damage. Fuel control unit pointer at 52 degrees (flight), anticipator at 30 degrees. All lines and connections tight. Gas generator and turbines rotated by hand. Power shaft continuity confirmed. Freewheeling assembly rotated smoothly. No foreign object damage. Magnetic plugs and chip detectors clean.
Tests and Research
Fuel and oil samples and the fuel filter element were tested. Fuel appeared typical of jet fuel; oil typical of MIL-PRF-23699. No anomalies. Filter element particulates included insect parts, wood fibers, paper filter piece, magnesium aluminum alloy pieces, paint chips, fluorosilicone gasket pieces, black and clear plastic, chlorocarbon tape, and glass fibers.
Both fuel pumps were tested with no anomalies.
The Vehicle Engine Multifunction Display (VEMD) was examined. The flight report for accident flight number 2547 lasted about 3 minutes. No failures or overlimits recorded. No impact-related outside air temperature sensor failures. It was likely that NG decreased below 50 percent before impact, indicating an engine flameout.
The engine was inspected and tested at Turbomeca USA and France. It ran for 51 minutes on a test bed with original equipment. Tests included reduced boost pump pressure and rapid deceleration; no flameout occurred. Various fuel system components and the axial compressor were examined; no findings explained the flameout.
The airframe fuel circuit was tested with transparent lines. Results confirmed correct operation. Tests also examined effects of operating the Le Bozec fuel filter drain valve or replacing the cartridge; air could be introduced and might not be purged during start or normal operation. The source does not state a conclusion regarding the cause.