Cessna U206G accident near Cave-In-Rock, Illinois, August 25, 2016
On August 25, 2016 at about 3:05 pm local time, a 1986 Cessna U206G, registered N891LL, was substantially damaged in an accident during enroute near Cave-In-Rock, Illinois. It was a public-use flight (state) under public-use (government) rules. 1 person was seriously injured and 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A total loss of engine power due to air entering the fuel system for reasons that could not be determined based on available information. Contributing to the accident was the pilot’s inability to restart the engine due to the check valve assembly design.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 25, 2016 · about 3:05 pm local time
- Place
- Cave-In-Rock, Illinois · map
- Type
- Accident
- Injuries
- 1 person was seriously injured and 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna U206G, built 1986 · all U206Gs on the register
- Registration
- N891LL · no longer on the register · serial U206-06937
- Damage
- Substantial damage
- Flight
- Public-use flight (state) · public-use (government) rules
The NTSB's narrative final · quoted from the NTSB record
The airline transport pilot and camera operator were conducting an aerial mapping flight. While level at 3,500 ft above ground level, the turbo propeller-equipped airplane experienced a total loss of engine power. The pilot attempted to restart the engine three times without success. During the subsequent forced landing, the airplane struck a berm, which damaged both wings. Examination of the engine revealed that fuel would not flow to the fuel nozzle until air pressure was bled upstream of the check valve assembly, located between the engine fuel control and the fuel nozzle. After the air pressure was bled and the fuel pump purged, normal fuel flow resumed, indicating that air had entered the fuel system. Because of the check valve assembly design, an in-flight engine restart was not possible after air entered the fuel line, and there was no procedure to clear air from the fuel line while in flight. Examination of the engine and fuel system could not establish a reason for air entering the fuel line.
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 defining event
- Hard landing during landing
The NTSB's findings
- cause Aircraft › Aircraft systems › Fuel system › (general) › Malfunction
- factor Aircraft › Aircraft power plant › Engine (turbine/turboprop) › (general) › Design
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instrument: airplane; rotorcraft: helicopter
- Flight time: 8,357 hours in all; 268 in this make and model; 43 in the last 90 days; 25 in the last 30 days; 7,135 as pilot in command; 2,560 on instruments
- Last flight review: October 9, 2015
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: minor injuries
Passenger
- Seat: rgt
- Injury: serious injuries
The aircraft
- Airframe total time: 6,170 hours
- Last inspection: annual inspection, February 4, 2016
- Maximum gross weight: 3,600 lb
- Seats: 2
- Landing gear: fixed
- Engine: Allison 250C20S (turboprop); 6,014 hours total
- Operator: State Of Illinois
The flight
- Departed from: SPI Springfield IL at 1:45 pm
- Destination: SPI Springfield IL
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 240° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 84°F (29°C), dew point 77°F (25°C)
- Altimeter: 30.10 inHg
- Observation at 3:15 pm from KHSB, 26 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
7 documents, released by the NTSB on May 23, 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 | Interview with Pilot | PDF, 1 page | View Download |
| 3 | Excerpt of Pilot Operating Handbook - Engine Restart Procedure During Flight | PDF, 1 page | View Download |
| 4 | Airframe and Engine Exam | PDF, 3 pages | View Download |
| 5 | Engine Run - Correspondence | PDF, 1 page | View Download |
| 6 | Fuel Flow Indicator - Specialist's Factual Report | PDF, 3 pages | View Download |
| 7 | Statement of Party Representatives to NTSB Investigation | PDF, 4 pages | 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.