# Accident 20240926014629A: Bell 206L, Fern Prairie, WA, September 26, 2024

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: September 26, 2024, 16:00 local time
- Place: Fern Prairie, WA
- Damage: Substantial damage
- Phase of flight: Cruise/Level Flight
- Operating rules: General operating rules (Part 91)
- Location: 45.6541° N, 122.3041° W: From the FAA
- Nearby events: https://openairdocs.org/map.md?lat=45.6541&lon=-122.3041&mi=10
- Aircraft: N9984K, registered now (https://openairdocs.org/aircraft/N9984K) (OpenAirDocs)
- Registry model: Bell 206L (registry code 1181522, https://openairdocs.org/model/bell-206l) (OpenAirDocs)
- Registry engine: Allison 250-C20 series (registry code 03020, https://openairdocs.org/engine/allison-250-c20-series) (OpenAirDocs)
- Reported make and model: BELL 206L
- Reported engine: ALLISON 250-C20 SER
- People aboard: 1
- Fatal injuries: 0
- Other injuries: 0
- NTSB investigation: [NTSB WPR24LA319](https://openairdocs.org/ntsb/WPR24LA319) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/20240926014629A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

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.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB WPR24LA319](https://openairdocs.org/ntsb/WPR24LA319), Sep 26, 2024: Bell 206L (N9984K), Fern Prairie, WA, substantial damage. Probable cause: An aeroelastic interaction between the helicopter’s main rotor blades and nodal beam system, which resulted in oscillations that exceeded the design limits of the tailboom. Contributing to the…

## Other reports on N9984K (1)

Matched to the same aircraft by N-number and date.

- [Incident 19800926080739I](https://openairdocs.org/incident/19800926080739I), Sep 26, 1980: Bell 206L (N9984K), Venice, LA. Engine failed in cruise. Pilot autorotated to landing in the gulf. Fuel control oil pump failed.

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.