NTSB Factual Report

On October 3, 2005, at 1710 Pacific daylight time, an Aerospatiale AS350B, N31MH, encountered a ground resonance event following a hard landing at the Grand Canyon Airport (GCN), Grand Canyon, Arizona. The commercial rotorcraft pilot and six passengers were not injured; the helicopter sustained substantial damage. The helicopter was registered to, and operated by, Maverick Helicopters, Las Vegas, Nevada, as a sightseeing flight under the provisions of 14 CFR Part 135. The tour flight originated from GCN at 1647, and was terminating at the time of the accident. Visual meteorological conditions prevailed, and a company visual flight rules flight plan had been filed.

According to the pilot's written statement, he established the helicopter in a 3-foot hover and taxied to the helipad. As the helicopter neared the helipad, a "gust of wind lifted the aircraft into a 5- to 6-foot hover." The pilot regained control and reestablished the helicopter in a 3-foot hover and began lowering the collective to land. At 1.5 feet above the ground, another gust of wind "slammed" the helicopter onto the ground, impacting the terrain with the right front skid. A "violent vibration" began, and the pilot pulled the helicopter up in the air after realizing he was in a ground resonance situation. The vibrations dissipated, and the pilot set the helicopter down and shut off the engine.

The helicopter sustained substantial damage to its tail boom. Post accident examination of the landing skid system revealed that the spring-steel extensions were within limits and the dampers were in serviceable condition. The pilot did not report any anomalies with the helicopter prior to the event.

The pilot reported that the winds were from the south at 18 knots with gusts to 36 knots.

NTSB Probable Cause

the pilot's failure to maintain control of the helicopter during landing in gusty wind conditions, which resulted in a hard landing and ground resonance.