Beech A36 accident near Ennis, Montana, June 6, 2006
On June 6, 2006 at about 1:00 am local time, a Beech A36, registered N24BF, was substantially damaged in an accident near Ennis, Montana (Ennis - Big Sky airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 4 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The loss of engine power during takeoff due to an excessively lean fuel-to-air mixture ratio as a result of excessive mating surface wear between the mixture control arm and metering shaft. A factor was the improper installation of the new engine, which resulted in excessive wear and metering of fuel and loss of engine power. An additional factor was the rough, uneven terrain.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 6, 2006 · about 1:00 am local time
- Place
- Ennis, Montana · Ennis - Big Sky · map
- Type
- Accident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Beech A36 · all A36s on the register
- Registration
- N24BF · registry record · serial E1736
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that shortly after takeoff the airplane lost engine power and he elected to land in an open field south of the airport. Post accident evaluation and testing of the mixture control linkage revealed that the metering shaft rotated to the mechanical stop when actuated to the "idle cut-off" position; however, when the mixture control was actuated to the "full-rich" position, the metering shaft rotated approximately 40 percent of potential (full) travel and did not reach the mechanical stop. Further examination revealed the mixture control arm retaining nut was tight, however extensive wear to the serrated mating surfaces of the mixture control arm and metering shaft was observed. The serrated edges had worn smooth and fretting type damage was noted to both surfaces. Maintenance records showed that the airplane's original engine, a Continental IO-520, was removed and the airframe was retrofitted with a factory rebuilt (zero time) IO-550-B in accordance with a Supplemental Type Certificate (STC). The certified airframe and power plant (A&P) mechanic, who performed the maintenance on the airplane, stated the mixture control arm (which was shipped with the engine) was installed in conjunction with the engine conversion.
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; instrument: airplane
- Flight time: 1,800 hours in all; 700 in this make and model
- Last flight review: May 1, 2006
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 3,465 hours
- Last inspection: annual inspection, March 1, 2006; 35 hours since
- Maximum gross weight: 3,600 lb
- Seats: 6
- Landing gear: retractable
- Engine: Continental IO-550B (piston); 0 hours total
The flight
- Departed from: KEKS Ennis MT at 11:00 pm
- Destination: 6S5 Hamilton MT
- Flight plan: none
- Runway 16, 4,694 ft by 75 ft
Weather at the time
- Light: daylight
- Wind: from 180° at 10 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.