LAX06LA161 · Bell 206B3
Bell 206B3 · Accident: airframe, component or system failure en route
From Fallbrook, CA to an unrecorded destination
Event
- NTSB case
- LAX06LA161
- 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 206B3
- 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
- N2763R
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Fallbrook, CATo not recorded
- Aircraft age
- Not recorded
- 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 · cruise
- First occurrenceThe 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
- Airframe, component or system failure
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- 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
- Company maintenance personnel › Maintenance, improper
- Lubricant, grease › Inadequate
- Rotor drive system, engine to transmission drive › Failure
- Rotor drive system, engine to transmission drive › Overtemperature
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The helicopter collided with trees following a failure of the engine to transmission drive shaft. After finishing a final rinse load for the agricultural spray operation, the pilots began the short return flight back to a trailer. While maneuvering about 20 feet above ground level (agl), and about 5 feet above the treetops, the helicopter made an uncommanded yaw and settled into the trees. A post accident examination revealed that the engine to transmission drive shaft (short shaft) was separated at the forward coupling flange, adjacent to the transmission. Investigators removed the rust-covered engine to transmission drive shaft forward coupling from the gear. The retainer ring, packing seal, and drive shaft coupling seal were not attached to the coupling and dangling loosely on the drive shaft tube. A visual examination of the internal coupling revealed that grease retainer plate had a shiny polished appearance from the gear sprocket making repetitive contact with its surface. The engine to transmission drive shaft forward gear sprocket teeth were not present, as a result of overheating and persistent contact, which had worn them smooth. On the face of the gear sprocket there was a semicircular indentation that had the shape and dimension consistent with that of a partial impression of the spring that is normally inside the coupling. Pieces of the spring were found deformed in the aft coupling housing. There was no evidence of grease in the forward coupling, and the aft coupling contained grease that was dirty and black. The operator's component card record for the engine to transmission drive shaft indicated that it was last inspected about 2 months prior to the accident at which time a mechanic repacked the couplings with grease. The helicopter's applicable Maintenance Manual indicated that every 600-hour or 12-month period (whichever occurs first) the main drive shaft component should be inspected.
Probable cause
Failure of the engine to transmission drive shaft forward coupling due to overheating from lack of lubrication. The cause of the lack of lubrication was a result of improper maintenance. A factor was the trees.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX06LA161
- Event ID
- 20060510X00546
- Case number
- LAX06LA161
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 636afffa034364381712e21308705125ba7f75ba863e806924e59414ae8f5a30; retrieved 2026-09-21T18:47:11.348Z.