Bell 206B3 accident near Fallbrook, California, May 4, 2006
On May 4, 2006 at about 4:30 pm local time, a Bell 206B3 (helicopter), registered N2763R, was substantially damaged in an accident near Fallbrook, California. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 4, 2006 · about 4:30 pm local time
- Place
- Fallbrook, California · map
- Type
- Accident
- Injuries
- 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206B3 · all 206B3s on the register
- Registration
- N2763R · no longer on the register · serial 2743
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 393 hours in all; 214 in this make and model; 57 in the last 90 days; 19 in the last 30 days; 322 as pilot in command
- Last flight review: November 1, 2004
- Medical certificate: Class 2
- Seat: rgt
- Injury: no injuries
Pilot (unmanned)
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Last flight review: November 1, 2004
- Medical certificate: Class 2
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 15,437.5 hours
- Last inspection: annual inspection, March 1, 2006; 37.5 hours since
- Maximum gross weight: 3,200 lb
- Seats: 2
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
The flight
- Departed from: Fallbrook CA at 4:25 pm
- Flight plan: none
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 270° at 2 knots
- Visibility: 8 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.