WPR24LA067 · Bell 206B
Bell 206B · Accident: system/component malfunction/failure (non-power) en route
From Brawley, CA to an unrecorded destination
Event
- NTSB case
- WPR24LA067
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Bell 206B
- Aircraft type
- Bell 206
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N111PM
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Brawley, CATo not recorded
- Aircraft age
- About 48 years (built 1975)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 137: Agricultural
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- System/component malfunction/failure (non-power)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft propeller/rotor
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot was flying in night visual flight rules (VFR) conditions about 100 ft above ground level (agl), toward an intended application site for agricultural pesticides, when the helicopter began to make a loud noise and vibrate. Unsure if the helicopter had lost rotor rpm or not, the pilot lowered the collective and initiated a run-on landing to a field. Postaccident examination of the helicopter’s airframe and engine revealed that the forward-most flex plate of the forward flex coupling on the KAflex driveshaft assembly was fractured. No evidence of additional preaccident mechanical malfunction or failure that would have precluded normal operation was observed. Fracture analysis revealed that the flex plate failed due to a fatigue fracture resulting from a loose attachment between the flex plate and the forward driveshaft fitting. Multiple areas of missing or replacement torque paint were observed throughout the KAflex driveshaft assembly’s joints. It is likely that the joints had either slipped or been manually disturbed before the non-original torque paint was applied, which would have been cause for the driveshaft assembly to be removed and shipped to the manufacturer. However, no evidence of the driveshaft’s removal after visual confirmation of joint slippage or disturbance was recorded in the aircraft maintenance logs.
Probable cause
An in-flight failure of the engine-to-transmission driveshaft due to a fatigue fracture of the forward-most flex plate in the forward KAflex coupling that resulted from a loose bolt attachment between the flex plate and the forward driveshaft coupling. Contributing to the accident was maintenance personnel’s failure to identify the condition and remove the KAflex driveshaft for repair as specified by the manufacturer.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR24LA067
- Event ID
- 20240108193630
- Case number
- WPR24LA067
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status, cause areas. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2023-12-24.
- API snapshot SHA-256: a785a7ca5b1209bd42498b3db80c78472ee2502c98cd6d95c94b021c9bc16015; retrieved 2026-09-16T18:25:27.449Z.