Cessna TU206G accident near Saint Ignatius, Montana, August 3, 2015
On August 3, 2015 at about 4:00 pm local time, a 1984 Cessna TU206G, registered N235HM, was substantially damaged in an accident during enroute (cruise) near Saint Ignatius, Montana. It was a personal 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).
The NTSB's probable cause their words, unchanged
Maintenance personnel’s failure to tighten a fuel line, which resulted in a loss of fuel pressure and a subsequent loss of engine power during cruise flight and an off-airport landing and collision with obstacles.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 3, 2015 · about 4:00 pm local time
- Place
- Saint Ignatius, Montana · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna TU206G, built 1984 · all TU206Gs on the register
- Registration
- N235HM · no longer on the register · serial U20606795
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was conducting the airplane's first flight since the engine had undergone maintenance several months earlier. He reported that, after about 45 minutes of flight, he noticed that the exhaust gas temperature (EGT) had increased but that he was able to reduce the temperature by increasing the fuel flow. Shortly after, the EGT again increased, and the pilot began to troubleshoot the issue. The pilot stated that, after he turned the electric fuel boost pump on a second time, the engine ran normally for about 2 minutes and then lost power. He determined that the airplane would be unable to reach the airport, so he initiated a forced landing to a road. During the landing roll, the airplane struck vegetation and a fence. During a postaccident examination of the airplane, blue fuel stains were observed on the top of the engine. The fuel line attached to the fuel flow transducer was found finger tight and leaking. A review of the airplane's maintenance records indicated that, during the maintenance conducted several months before the accident, three cylinders, including the No. 6 cylinder, had been removed and reinstalled. The fuel line attached to the fuel flow transducer was just above the No. 6 cylinder and, therefore, it would been removed to access the cylinder during the maintenance. It is likely that maintenance personnel did not adequately tighten the fuel line during its reinstallation, which led to the loss of fuel pressure and the subsequent loss of engine power.
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
What happened, in order
- Loss of engine power (total) during enroute (cruise) defining event
- Off-field or emergency landing during landing
The NTSB's findings
- cause Personnel issues › Task performance › Maintenance › Repair › Maintenance personnel
- cause Aircraft › Aircraft systems › Fuel system › (general) › Incorrect service/maintenance
- Environmental issues › Physical environment › Object/animal/substance › Fence/fence post › Contributed to outcome
Pilot
- Certificate: private
- Ratings: single-engine land; single-engine sea
- Flight time: 950 hours in all; 200 in this make and model; 910 as pilot in command
- Medical certificate: Unknown
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 2,316 hours
- Last inspection: annual inspection, February 17, 2015
- Seats: 4
- Landing gear: fixed
- Engine: Continental Motors, Inc. TSIO520M (piston); 2,316 hours total
The flight
- Departed from: B2N Bozeman MT at 2:12 pm
- Destination: 8S1 Polson MT
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 200° at 8 knots
- Visibility: 7 statute miles
- Sky: a few clouds at 11,000 ft
- Temperature: 66°F (19°C), dew point 37°F (3°C)
- Altimeter: 29.92 inHg
- Observation at 3:53 pm from KMSO, 24 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.
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.