Final Report: Helicopter encountered ground resonance
Aerospatiale SA 319B, Escalante, Utah, Dec. 14, 2005–The NTSB said the probable cause of the SA 319 accident was the pilot’s inadequate remedial action when the helicopter entered ground resonance. The rough/uneven terrain and inadequate company maintenance were contributing factors.
The pilot of the 30-year-old helicopter touched down on a sloping rock outcrop and the aircraft began to oscillate. He said he pulled up on the collective, and then the helicopter “suddenly self-destructed.” One rotor blade hit the cabin and injured a passenger.
Investigators identified a number of maintenance discrepancies, including improper tire inflations, improper main landing gear hydraulic shock strut pressures and differential functioning of the main rotor blade drag dampers.