History of Flight
On March 6, 2015, at 2310 central standard time, an Airbus Helicopters (Eurocopter) EC-130-B4, registration N356AM, operated by Air Methods (doing business as ARCH), struck the edge of a hospital building and impacted its parking lot during a visual approach to the St Louis University Hospital elevated rooftop helipad (MO55) in St. Louis, Missouri. During the approach, the helicopter experienced a loss of directional control and entered an uncontrolled descent. The helicopter was destroyed by impact forces and a post-crash fire. The commercial pilot, the sole occupant, sustained fatal injuries. The flight was operating under 14 CFR Part 91 as an air medical positioning flight on a company flight plan. Night visual meteorological conditions prevailed. The flight was returning to MO55 after refueling at the operator's base at Arch Heliport (MU05), St. Louis, Missouri.
The first approach and landing at MO55 earlier that evening involved dropping off a medic, nurse, and a patient. The medic reported that during the first approach, the pilot said the wind was 25 knots, and the windsock was illuminated and pointing straight out toward the elevator shaft. The medic noted the helicopter's tail was "sideways a little bit" during the approach, which felt lower than usual and closer to the elevator. The nurse recalled "a lot of rolling" and "a lot of yawing" and that the pilot had a "hard time" over the helipad. After landing, the pilot wanted to stay on the helipad but was told it could not remain due to other incoming helicopters. The flight then departed for fuel at MU05.
The accident occurred during the return approach to MO55. A witness saw a light approaching, then the helicopter took a "little tail spin" before going out of sight. The witness observed the helicopter at about 15 feet above an overhead tunnel and stated it spun once and went down at an angle. The wind was blowing north.
Personnel Information
The pilot held a commercial pilot certificate with rotorcraft-helicopter and instrument-helicopter ratings issued June 24, 1992. According to Air Methods, he had accumulated 2,614 total hours, all in rotorcraft. His FAA file indicated military competence obtained in the US Army, with at least 10 hours as pilot-in-command in the UH-1 in the preceding 12 months. His resume listed prior employment as an EC-130 pilot for air tour operations starting May 5, 2013, with total flight time of 2,244.7 hours, all military helicopter, and 1,155.7 hours PIC. He reported on his Air Methods application a total of 2,503.4 hours (all in helicopters), 1,338.8 hours PIC, and 250 hours in the EC-130-B4. He completed initial Part 135 checkrides on November 20, 2013, and was assigned as an EC-130/EC130NVG pilot on December 1, 2013. No previous FAA incident, accident, or enforcement actions were recorded.
Aircraft Information
N356AM was a 2010 Airbus Helicopters EC-130-B4, serial number 7006, configured for EMS operations. It was powered by a Turbomeca Arriel 2B1 turboshaft engine. The last inspection occurred on March 5, 2015, at an airframe and engine total time of 1,378.4 hours.
Meteorological Information
The 2100 sounding wind profile indicated surface wind from 183 degrees at 7 knots, increasing to 25 knots by 1,300 feet msl and becoming southwesterly. Sustained wind speeds reached 30 knots at 2,000 feet msl. At 0000, similar conditions persisted with winds around 40 knots at 2,000 feet msl. The inversion height was critical, with stable air below 2,000 feet msl; mixing would have caused moderate or greater turbulence and low-level wind shear (LLWS). RAOB data indicated likely LLWS below 3,000 feet msl and clear air turbulence likely from the surface through 6,500 feet msl. The accident flight would have likely experienced LLWS, clear air turbulence, and wind speeds up to 40 knots between the surface and 2,000 feet msl.
Wreckage and Impact Information
The main wreckage was near the west parking lot entrance, with debris over an area about 30 feet in diameter. The helicopter was oriented approximately northeast. Blue witness marks on the north side of the west entrance were consistent with a tail strike. Flight control continuity of the tail rotor drive system was confirmed, but functional testing could not be performed due to impact and fire damage. The engine exhibited foreign object damage on several axial blades; the gas generator and accessory gearbox could not be rotated. The reduction gearbox input pinion alignment mark was in the over-torqued 4mm position, consistent with engine power.
Medical and Pathological Information
An autopsy conducted on March 7, 2015, determined the cause of death as thermal burns and smoke inhalation. The FAA toxicology report showed no carbon monoxide, no ethanol, and no listed drugs detected.
Fire
A post-crash fire and explosion occurred upon impact, captured by security video. Frames show the fire/explosion at 11:17:14 PM and a fire ball separating and moving upward and left, consistent with wind direction.
Survival Aspects
The autopsy described severe thermal injuries and soot deposition in the respiratory tract. Traumatic injuries included a hairline frontal bone fracture, sternal fracture, and fifth cervical vertebra fracture without spinal cord injury. Coronary artery disease with 80% narrowing was identified but no focal lesions. On March 23, 2016, the NTSB issued safety recommendations regarding EC-130-B4 and AS-350-B3e fuel tank breaches leading to postcrash fires.
Tests and Research
No sufficient radar data or nonvolatile memory was available for a performance study. Security video analysis showed the helicopter's landing light illuminating the building, then moving left, with a flash at 11:17:06 PM and the helicopter descending at about a 45-degree angle.
The Helicopter Flying Handbook describes vortex ring state (settling with power) as an aerodynamic condition in a vertical descent with power applied. The handbook also discusses critical wind azimuth and loss of tail rotor effectiveness. The EC-130-B4 flight manual did not contain wind limits or a critical wind azimuth chart. Airbus Helicopters provided an analysis showing pedal control and power requirements relative to azimuth and wind speed.
A pilot with extensive EMS experience stated that flying into MO55 is "not that bad" but that the approach is "almost a one way in and one way out." He noted that the EC-130 vertical fin is "extremely affected by a lot of wind" and that tail rotor pedal input may reach stops. He also mentioned possible exhaust gas contamination of Finestron blade roots causing blade sticking.
The pilot completed a risk assessment form on March 6, 2015, at 1751, with a total score of 28, classified as low risk. Item 3 (pilot has less than 3,000 total rotor wing flight hours) was left blank.
An accredited representative from the BEA participated as the state of manufacture.