Amateur-built BF9 2 accident near Evanston, Wyoming, May 31, 2018
On May 31, 2018 at about 11:45 pm local time, a 2008 amateur-built BF9 2, registered N81973, was substantially damaged in an accident during enroute near Evanston, Wyoming. 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
The pilot’s failure to fuel the biplane’s main fuel tank before the flight and his inadequate preflight inspection, during which he did not verify the fuel quantity, which resulted in fuel exhaustion
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 31, 2018 · about 11:45 pm local time
- Place
- Evanston, Wyoming · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built BF9 2 NO SERIES, built 2008
- Registration
- N81973 · registry record · serial 24601-001
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the biplane reported that he believed he had departed with 38 gallons of fuel in the main fuel tank and 17 gallons in the auxiliary fuel tank. En route, the auxiliary fuel tank ran dry, so he switched to the main fuel tank, which he believed had 35 gallons of fuel remaining. The pilot reported that, while descending to the destination airport, the engine experienced a loss of power. He added that he believed the throttle linkage had broken and that the carburetor was at idle. During the forced landing, he aligned the airplane with a highway and observed four semi-tractor trailers but thought they were ahead of his flightpath. The biplane struck one of the semi-tractor trailers, violently turned right, and then came to rest inverted on the right side of the highway. The biplane sustained substantial damage to the left wings. Postaccident examination revealed that the main fuel tank was empty, and the throttle linkage was intact. The pilot reported that his typical fueling process is to fuel the main fuel tank before fueling the auxiliary fuel tank. He added that he reviewed fuel receipts and found that, before the accident flight, he fueled the auxiliary fuel tank first and, while following his routine, believed that the main fuel tank had already been fueled. This resulted in a departure with 10 gallons of fuel less than planned. The pilot reported that there were no preaccident mechanical failures or malfunctions with the biplane that would have precluded normal operation.
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
- Aircraft servicing event during prior to flight
- Fuel exhaustion during enroute defining event
- Loss of engine power (total) during landing
- Off-field or emergency landing during landing
- Collision with terrain or object (not controlled flight into terrain) during landing
- Nose over/nose down during landing
The NTSB's findings
- cause Aircraft › Fluids/misc hardware › Fluids › Fuel › Fluid level
- cause Personnel issues › Task performance › Planning/preparation › Fuel planning › Pilot
- cause Personnel issues › Task performance › Inspection › Preflight inspection › Pilot
- Environmental issues › Physical environment › Object/animal/substance › Ground vehicle › Contributed to outcome
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land
- Flight time: 2,016 hours in all; 310 in this make and model; 33 in the last 90 days; 12 in the last 30 days; 1,980 as pilot in command
- Last flight review: October 5, 2016
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rear
- Injury: no injuries
The aircraft
- Airframe total time: 309.8 hours
- Last inspection: condition inspection, March 23, 2018
- Maximum gross weight: 2,250 lb
- Seats: 2
- Landing gear: fixed
- Engine: Vendenyev M-14P (piston); 1,038 hours total
The flight
- Departed from: LMO Longmont CO at 9:00 pm
- Destination: EVW Evanston WY
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 220° at 19 knots, gusting 25
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 72°F (22°C), dew point 28°F (-2°C)
- Altimeter: 29.82 inHg
- Observation at 11:53 pm from KEVW, 2 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
2 documents, released by the NTSB on September 10, 2018. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Accident Photo | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.