Bell 206 L-3 accident near Rifle, Colorado, November 24, 1999
On November 24, 1999 at about 7:30 pm local time, a Bell 206 L-3 (helicopter), registered N617DE, was substantially damaged in an accident near Rifle, Colorado. It was a public-use flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
a forced landing on rough, unsuitable terrain. A contributing factor was the partial loss of engine power, which resulted from improper maintenance by repair station personnel.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 24, 1999 · about 7:30 pm local time
- Place
- Rifle, Colorado · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206 L-3 · all 206 L-3s on the register
- Registration
- N617DE · registry record · serial 51138
- Damage
- Substantial damage
- Flight
- Public-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While on a cross-country positioning flight in cruise flight, the helicopter's engine lost partial power, and the pilot conducted an autorotation to a field, which was rough and uneven. During the landing sequence, the lower wire cutter dug into the uneven ground, the helicopter rocked forward and the skid support cross tubes buckled aft. As the helicopter settled, a main rotor blade struck the left winglet of the horizontal stabilizer, and the tail boom was wrinkled. Examination of the engine revealed that the angular contact ball bearing on the power takeoff shaft had failed. The balls from the bearing had fallen into the gearbox oil sump, and a ball had lodged in the oil exit port, blocking the flow of oil out of the gearbox. The gearbox filled with oil, the oil tank emptied, and power section components began to overheat due to lubricating oil starvation. Engine records provided evidence that during maintenance performed 28.7 hours prior to the engine failure, repair station personnel had removed, inspected and reinstalled the failed bearing. Examination of the bearing provided evidence that it had been pressed apart and reassembled with the outer race reversed. The manufacturer authorizes no disassembly of the bearing. According to the manufacturer, with the outer race reversed, the bearing will immediately start to deteriorate when placed in service.
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: airline transport pilot, flight instructor
- Ratings: single-engine land; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 11,154 hours in all; 8,000 in this make and model; 200 in the last 90 days; 100 in the last 30 days; 11,000 as pilot in command
- Medical certificate: Class 1 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 8,724 hours
- Last inspection: 100-hour inspection, November 3, 1999; 29 hours since
- Maximum gross weight: 4,150 lb
- Seats: 7
- Landing gear: fixed
- Engine: Allison 250-C30P (turboshaft); 0 hours total
The flight
- Departed from: MTJ Montrose CO at 7:00 pm
- Destination: CAG Craig CO
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 310° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 93°F (34°C), dew point 61°F (16°C)
- Altimeter: 30.00 inHg
- Observation at 7:54 pm from RIL, 8 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
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.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number DEN00GA022.