What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
At approximately, 11:15(l), the pilot maneuvered the aircraft close to a steep mountain slope performing a toe-in landing against the steep slope to allow the dwr passengers to perform their work. The pilot reported that while the helicopter was in a stable hover against the mountain slope, there was suddenly a “big bang”, and the helicopter began to descend and violently shuddered. The pilot attempted to maneuver away from the slope, but the helicopter slid down the slope and rolled coming to rest on its left side. The pilot stated that he suspected a loose rock may have fell into the main rotor system or the main rotor blades contacted the slope. The helicopter sustained substantial damage to the fuselage, main rotor, and tail cone sections. The pilot further stated that there were no mechanical malfunctions or failures that would have precluded normal operations.
As the FAA filed it
AT APPROXIMATELY, 11:15(L), THE PILOT MANEUVERED THE AIRCRAFT CLOSE TO A STEEP MOUNTAIN SLOPE PERFORMING A TOE-IN LANDING AGAINST THE STEEP SLOPE TO ALLOW THE DWR PASSENGERS TO PERFORM THEIR WORK. THE PILOT REPORTED THAT WHILE THE HELICOPTER WAS IN A STABLE HOVER AGAINST THE MOUNTAIN SLOPE, THERE WAS SUDDENLY A “BIG BANG”, AND THE HELICOPTER BEGAN TO DESCEND AND VIOLENTLY SHUDDERED. THE PILOT ATTEMPTED TO MANEUVER AWAY FROM THE SLOPE, BUT THE HELICOPTER SLID DOWN THE SLOPE AND ROLLED COMING TO REST ON ITS LEFT SIDE. THE PILOT STATED THAT HE SUSPECTED A LOOSE ROCK MAY HAVE FELL INTO THE MAIN ROTOR SYSTEM OR THE MAIN ROTOR BLADES CONTACTED THE SLOPE. THE HELICOPTER SUSTAINED SUBSTANTIAL DAMAGE TO THE FUSELAGE, MAIN ROTOR, AND TAIL CONE SECTIONS. THE PILOT FURTHER STATED THAT THERE WERE NO MECHANICAL MALFUNCTIONS OR FAILURES THAT WOULD HAVE PRECLUDED NORMAL OPERATIONS.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.