What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On September 26th the pilot was flying, from toutle, WA to boring Oregon single pilot, no cargo and 150 lbs of fuel. Around 4:00 pm the pilot experienced sudden onset severe/extreme main rotor vibration while in normal cruise flight at 1000 ft AGL and 95KTS. Pilot immediately lowered the collective to accomplish an emergency descent and landing. The vibration, which lasted for about 7 seconds, was so extreme that the cabin filled with dust and the gages were unreadable due to the shudder. The vibration began to subside when pilot turned the aircraft and started to decelerate for landing. It completely subsided at 300 ft AGL. The pilot was able to bring the aircraft in to a hover and land it along side a gravel road. All systems were normal with the exception of application of forward cyclic required unusual additional pressure. After shutting down the aircraft, a visual inspection found the tail boom had severly buckled on the bottom forward section aft of the mount bolts.
As the FAA filed it
ON SEPTEMBER 26TH THE PILOT WAS FLYING, FROM TOUTLE, WA TO BORING OREGON SINGLE PILOT, NO CARGO AND 150 LBS OF FUEL. AROUND 4:00 PM THE PILOT EXPERIENCED SUDDEN ONSET SEVERE/EXTREME MAIN ROTOR VIBRATION WHILE IN NORMAL CRUISE FLIGHT AT 1000 FT AGL AND 95KTS. PILOT IMMEDIATELY LOWERED THE COLLECTIVE TO ACCOMPLISH AN EMERGENCY DESCENT AND LANDING. THE VIBRATION, WHICH LASTED FOR ABOUT 7 SECONDS, WAS SO EXTREME THAT THE CABIN FILLED WITH DUST AND THE GAGES WERE UNREADABLE DUE TO THE SHUDDER. THE VIBRATION BEGAN TO SUBSIDE WHEN PILOT TURNED THE AIRCRAFT AND STARTED TO DECELERATE FOR LANDING. IT COMPLETELY SUBSIDED AT 300 FT AGL. THE PILOT WAS ABLE TO BRING THE AIRCRAFT IN TO A HOVER AND LAND IT ALONG SIDE A GRAVEL ROAD. ALL SYSTEMS WERE NORMAL WITH THE EXCEPTION OF APPLICATION OF FORWARD CYCLIC REQUIRED UNUSUAL ADDITIONAL PRESSURE. AFTER SHUTTING DOWN THE AIRCRAFT, A VISUAL INSPECTION FOUND THE TAIL BOOM HAD SEVERLY BUCKLED ON THE BOTTOM FORWARD SECTION AFT OF THE MOUNT BOLTS.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.
Other reports on N9984K · 1
Matched to the same aircraft by N-number and date.