SEA06TA028

The helicopter was manufactured in France for the French Army Air Force. Thirty years later, it was imported to California and given a Certificate of Airworthiness in the normal category by the Anchorage, Alaska, FAA FSDO. The helicopter was flying under contract for the Bureau of Land Management (Public Use) in southern Utah in support of an eradication of feral cattle program. The pilot said that he touched down on a sloping rock outcrop when the helicopter began to oscillate. The pilot pulled up on the collective and the aircraft "suddenly self-destructed." Five of the occupants exited the helicopter under their own power, however, one had been struck by a rotor blade and remained buckled in his seat unconscious. The ground resonance event separated the transmission/rotor system, the engine from the fuselage, and one main rotor blade impacted the cabin. The pilot said that he had experienced at least two incipient ground resonance events with this helicopter during the previous 18 months. During a post-accident examination, numerous maintenance discrepancies were identified, including: improper tire inflations, improper main landing gear hydraulic shock strut pressures, and differential functioning of the main rotor blade drag dampers. The manufacturer's representative said that all of these items have narrow operational tolerances if ground resonance events are to be avoided. Additionally, the landing surface was a "bowl shaped" rock formation with the right main landing wheel up sloped approximately 5 degrees and the nose wheel 3-5 inches nose low.

On December 14, 2005, at 1457 mountain standard time, an Aerospatiale SA-319B, Alouette III helicopter, N3194K, was destroyed by ground resonance encountered during a landing attempt in the Grand Staircase-Escalante National Monument, near Escalante, Utah. The commercial pilot and three passengers were not injured; however, two passengers were seriously injured. The helicopter was being operated under contract to the Bureau of Land Management (BLM) by High Country helicopters LLC. of Cedar City, Utah, as a public use flight. Visual meteorological conditions prevailed for the cross-country flight that had originated at Page, Arizona, approximately 30 minutes before the accident. No flight plan had been filed; BLM personnel stated that the purpose of the flight was to distribute hunters for eradication of feral cattle.

The pilot stated that he was moving hunting personnel from one location to another. He said that he "took about 5 seconds to settle all three tires to a stable footing and then put the collective down to a full-flat pitch." He said the "aircraft settled into a stable position when suddenly we experienced some ground resonance." The pilot said that he pulled the collective up to lift the helicopter off the ground and "suddenly it self-destructed." The ground resonance event separated the transmission/rotor system, the engine from the fuselage, and one main rotor blade impacted the cabin and struck the helmet of at least one rear seat occupant. Five of the occupants exited the aircraft under their own power, however, the occupant struck by the rotor blade was unconscious and remained buckled in his seat.

The pilot said that he had experienced at least two incipient ground resonance events with this helicopter during the previous 18 months.

The helicopter was manufactured in France on January 1, 1972, under contract for the French Army Air Force, and after it was decommissioned, it was sold to a company in California in 2002. On December 16, 2002, the helicopter received a Certificate of Airworthiness in the normal category from the Anchorage, Alaska, Federal Aviation Administration (FAA) Flight Standards District Office (FSDO). On March 17, 2005, it was put on a Part 135 certificate by the Salt Lake City, Utah, FAA FSDO. On May 12, 2005, the helicopter was approved and given a Department of Interior, Interagency Data Card, OAS-36B; this card made the helicopter eligible for the BLM contract.

On February 8 and 9, 2006, three FAA inspectors, two Department of Interior Air Safety Investigators, and a manufacturer's representative examined the helicopter in Cedar City, Utah. They identified numerous maintenance discrepancies including: improper tire inflations, improper main landing gear hydraulic shock strut pressures, and differential functioning of the main rotor blade drag dampers (tested by hand). The manufacturer's representative said that all of these items have narrow operational tolerances if ground resonance events are to be avoided. Additionally, the landing surface was a "bowl shaped" rock formation with the right main landing wheel up sloped approximately 5 degrees and the nose wheel 3-5 inches nose low.