Bell 407 accident near Kalispell, Montana, November 3, 2006
On November 3, 2006 at about 3:55 am local time, a Bell 407 (helicopter), registered N407KH, was substantially damaged in an accident near Kalispell, Montana (Kalispell Regional Hospital airport). It was a positioning flight under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
On-speed failure of the second stage turbine wheel as the result of engine oil starvation. The lack of maintenance oversight was a contributing factor.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 3, 2006 · about 3:55 am local time
- Place
- Kalispell, Montana · Kalispell Regional Hospital · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 407 · all 407s on the register
- Registration
- N407KH · registry record · serial 53395
- Damage
- Substantial damage
- Flight
- Positioning flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While conducting EMS operations the helicopter sustained substantial damage after a loss of engine power, autorotation, and forced landing. The pilot reported hearing a loud bang, followed by the engine spooling down. The helicopter collided with a chain link fence during the forced landing sequence. Postaccident inspection of the engine revealed an uncontained second stage turbine wheel burst (on-speed) as a result of oil starvation and subsequent bearing failure. During the onsite examination, fresh oil residue was noted along the right side of the helicopter's fuselage, tail boom assembly and leading edges of the tail rotor blades. Oil wetting and staining was also observed on the concrete hangar apron, and a trail of fresh oil extended from apron to the helipad where the helicopter departed. Additionally, onsite investigators noted that the oil pressure transducer line coupling B-nut (near the foreword bulkhead) was found two flats loose, and four complete rotations from complete separation. Evidence of oil loss, sooting and localized fire damage was observed in the area of the fitting union. The accident flight was the helicopter's first flight following the completion of a maintenance action item in the general area of the aforementioned fitting. Following the maintenance action, an engine run (ground) and post run inspection was completed by a line pilot. No discrepancies were noted and the helicopter was returned to service. The mechanic who performed the maintenance action was not present during the post run inspection.
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, military
- Ratings: single-engine land; instrument: helicopter; rotorcraft: helicopter
- Flight time: 3,000 hours in all; 593 in this make and model; 43 in the last 90 days; 14 in the last 30 days; 2,500 as pilot in command
- Last flight review: May 1, 2006
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 3,138 hours
- Last inspection: approved inspection programme, September 1, 2006; 68 hours since
- Maximum gross weight: 5,250 lb
- Seats: 5
- Landing gear: fixed
- Engine: Rolls-Royce 250 C47 (turboshaft); 0 hours total
The flight
- Departed from: MT28 Kalispell MT at 6:51 am
- Destination: Kalispell MT
- Runway H
Weather at the time
- Light: night, dark
- Wind: at 0 knots
- Visibility: 2 statute miles
- Sky: overcast at 1,700 ft
- Temperature: 28°F (-2°C), dew point 27°F (-3°C)
- Altimeter: 29.95 inHg
- Observation at 3:55 am from KGPI, 6 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 |
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.