DEN00GA022 · Bell 206 L-3
Bell 206 L-3 · Accident: partial loss of engine power (mechanical failure) en route
From Montrose Regional Airport (MTJ) to Craig Moffat Airport (CAG)
Event
- NTSB case
- DEN00GA022
- 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
- 0
- 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 206 L-3
- 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
- N617DE
- Operator
- Western Area Power Admin
- Onboard fatalities
- Unknown
- Route
- From Montrose Regional Airport (MTJ), Montrose, COTo Craig Moffat Airport (CAG), Craig, CO
- 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 91: General Aviation
- 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
- Partial loss of engine power (mechanical failure)
- 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
- Terrain condition › None suitable
- Terrain condition › Rough/uneven
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN00GA022
- Event ID
- 20001212X20087
- Case number
- DEN00GA022
- 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. 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: d6b2034067b970a0531bd7244302fb12f8e3541ac78d5f22d1505fe3f6880009; retrieved 2026-09-22T13:38:05.700Z.