History of Flight
On January 2, 2013, at about 1245 central standard time, a Eurocopter EC130 B4 helicopter, registration N334AM, experienced a hard landing following a loss of engine power near Seminole, Oklahoma. The commercial pilot and three crew members on board were seriously injured. The helicopter sustained substantial damage. The flight was operated by Air Methods of Centennial, Colorado, under 14 Code of Federal Regulations Part 91 as a positioning flight. Visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed and activated. The helicopter departed from Seminole Regional Airport (KSRE), Seminole, Oklahoma, at 1242, en route to a hospital in Okemah, Oklahoma.
According to the pilot, shortly after takeoff while climbing through 1,600 to 1,700 feet mean sea level, he heard a sound like something striking the helicopter and the engine stopped producing power. He initiated an autorotation, made a right turn toward an open field, and while maneuvering, saw a previously undetected barbed wire fence. He increased collective pitch to clear the fence, then applied aft cyclic and increased collective. He did not recall the landing. A crew member recalled hearing a muffled thud sound, and the pilot notified the crew of the engine loss. During descent, the crew noted power lines and a fence, and the pilot maneuvered over the fence before impact.
Aircraft Information
The four-seat, single-engine helicopter was manufactured by Eurocopter in December 2009. It was configured for emergency medical services and powered by a 747 shaft-horsepower Turbomeca Arriel 2B1 turbine engine. The last inspection was an approved helicopter inspection program inspection on December 23, 2012, at a total airframe and engine time of 1,100.75 hours. The helicopter flew 1 hour 14 minutes on December 30, 2012, with no discrepancies noted. A daily inspection was performed on December 31, 2012, and January 2, 2013, by an A&P mechanic.
Wreckage and Impact Information
The accident site was in an open field about 4.8 nautical miles west-northwest of KSRE, at an elevation of 682 feet mean sea level. The helicopter came to rest upright on a magnetic heading of 262 degrees. The Fenestron separated and was found approximately 30 feet north of the main wreckage. Three primary ground scars near the final resting position were consistent with contact from the tail skid and the two landing skids. The location of the scars indicated a clockwise rotation of approximately 180 degrees following initial ground impact. A barbed-wire fence was located about 16 feet west of the tail skid scar and about 54 feet west of the main wreckage.
All three main rotor blades remained attached. The red blade exhibited trailing edge separation near the cuff and leading edge damage matching an impact mark on the tail boom and engine exhaust duct. The blue blade showed impact damage on the bottom, with light blue paint transfer marks, and trailing edge separation; its tip damage matched damage on Fenestron stators. The yellow blade had trailing edge damage and blue paint transfer marks on the bottom and leading edge. The engine remained installed; fuel, oil, and electrical connections were intact. Fuel tested negative for water. The air intake duct showed no cracks or blockages. Four axial compressor blades exhibited deformation opposite the direction of rotation, consistent with ingestion of soft body debris.
Tests and Research
An engine run on January 30, 2013, initially showed tailpipe fires; after replacing the hydromechanical unit (HMU), the engine operated normally to 100% RPM. A distinct whining noise at idle was consistent with deformation damage on the first-stage axial compressor blades. The original HMU was bench tested and functioned correctly.
Corrective Actions
Following the investigation, Air Methods issued a message on January 4, 2013, requiring pilot acknowledgment, with information on cold weather engine operations and a pre-flight precaution to inspect accessible internal surfaces of the engine air intake. The FAA released SAIB SW-08-03R3 on January 17, 2013, with updated recommendations for rotorcraft operation in icing or snowy conditions. Eurocopter released Safety Information Notice No. 2645-S-30 on October 31, 2013, reminding operators to inspect engine air intakes and recommending installation of the engine air intake cover promptly after shutdown in cold weather. Turbomeca released General Service Letter No. 2904/13 on January 10, 2014, emphasizing the SAIB and compliance with flight manual instructions.