Helio H-391B accident near Bozeman, Montana, December 6, 1985
On December 6, 1985 at about 9:34 pm local time, a Helio H-391B, registered N4101D, was substantially damaged in an accident near Bozeman, Montana. It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The NTSB has not yet published a probable cause for this accident. Investigations usually take one to two years; this page updates when the final report is released.
Source: NTSB aviation accident database, copy made October 12, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 6, 1985 · about 9:34 pm local time · cases in 1985
- Place
- Bozeman, Montana · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Helio H-391B · all H-391Bs on the register
- Registration
- N4101D · no longer on the register · serial 016
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
ACCORDING TO PERSONNEL IN THE AREA, THE PLT RADIOED HE HAD SMOKE IN THE COCKPIT AND WAS RETURNING TO GALLANTIN FIELD, HIS DEPARTURE POINT. LATER, THE PLT TRANSMITTED THAT THE ENG LOST TOTAL PWR AND HE WAS MAKING A FORCED LANDING. DURING THE INVESTIGATION, IT WAS ASCERTAINED THE WIRING BETWEEN THE INSTRUMENT PANEL AND THE MAGNETOS HAD BURNED EXTENSIVELY AND THE MAGNETO 'P' LEAD HAD SHORTED OUT.
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: private
- Ratings: single-engine land; single-engine sea
- Flight time: 3,200 hours in all; 42 in this make and model
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 583 hours
- Last inspection: 100-hour inspection, December 6, 1985
- Maximum gross weight: 2,900 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming GO-435 (piston); 0 hours total
The flight
- Departed from: BZN Bozeman MT at 9:26 pm
- Destination: Portland OR
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 132° at 3 knots
- Visibility: 34 statute miles
- Sky: broken clouds at 25,000 ft; scat at 12,000 ft
- Temperature: 25°F (-4°C), dew point 0°F (-18°C)
- Altimeter: 30.00 inHg
- Observation at 9:35 pm from BZN, 2 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.
Connections how this case links to the rest of the register
- N4101D: not on the register today · the record of its deregistration
- Helio H-391 16 registered today · the model family and its accident history
- Helio 120 aircraft on the register
- Engine: Lycoming GO-435 33 aircraft carry this series today · as the NTSB recorded it
- Bozeman Yellowstone International · departed from
- Accidents and incidents in Montana 1,119 since 1982 · 164 in the last ten years
- Montana 6,049 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/DEN86LA040.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
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 does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.