Cessna U206C accident near Challis, Idaho, September 20, 2023
On September 20, 2023 at about 8:45 pm local time, a 1967 Cessna U206C, registered N3923G, was substantially damaged in an accident during takeoff near Challis, Idaho (Bernard Usfs airport). It was a business flight under charter and air-taxi rules (Part 135). 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 failure of the left main landing gear spring assembly due to a fatigue crack. Contributing to the accident was the improper maintenance on the landing gear spring assembly which allowed corrosion to develop.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 20, 2023 · about 8:45 pm local time
- Place
- Challis, Idaho · Bernard Usfs · map
- Type
- Accident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna U206C, built 1967 · all U206Cs on the register
- Registration
- N3923G · registry record · serial U206-0923
- Damage
- Substantial damage
- Flight
- Business flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The pilot was in the process of taking off when the left main gear spring assembly fractured. The airplane veered off the runway and ground contact substantially damaged the left horizontal stabilizer and elevator. Metallurgical examination of the failed gear spring assembly revealed it failed due to fatigue cracking and overload stresses. Further examination revealed corrosion underneath the primer paint and inside the dimples of the shot-peened area, which likely initiated the development of the fatigue crack. A records review revealed that in March of 2010, the left and right main gear spring assemblies were inspected, heat treated, shot peened and painted with a zinc-rich primer. It is likely that corrosion existed on the landing gear before the application of the primer paint, and that the inadequate removal of the corrosion allowed fatigue cracking to propagate until the left assembly failed in overstress.
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
- Landing gear collapse during takeoff defining event
- Aircraft maintenance event during prior to flight
The NTSB's findings
- Aircraft › Aircraft systems › Landing gear system › Main landing gear › Fatigue/wear/corrosion
- Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Maintenance personnel
Pilot
- Certificate: flight instructor, commercial pilot, private
- Ratings: single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 980.5 hours in all; 204 in this make and model; 224.6 in the last 90 days; 80 in the last 30 days; 900 as pilot in command; 8.1 on instruments
- Last flight review: August 6, 2023
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: no injuries
Passenger
- Seat: rgt
- Injury: no injuries
Passenger
- Seat: left
- Injury: no injuries
Passenger
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 10,473.2 hours
- Last inspection: annual inspection, August 15, 2023
- Maximum gross weight: 3,600 lb
- Seats: 5
- Landing gear: fixed
- Engine: Continental IO-550 (piston); 3,043 hours total
- Operator: Middle Fork Aviation INC
The flight
- Destination: LLJ Challis ID
- Runway 17/3, 1,900 ft by 150 ft
Weather at the time
- Light: daylight
- Wind: from 360° at 3 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 11,000 ft; clear
- Temperature: 66°F (19°C), dew point 34°F (1°C)
- Altimeter: 29.77 inHg
- Observation at 3:56 pm from KSMN, 37 miles away
Weather report (METAR): KSMN 202156Z AUTO 36003KT 10SM BKN110 19/01 A2977 RMK AO2 SLP782 T01890006
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 3 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
6 documents, released by the NTSB on February 26, 2025. 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, 8 pages | View Download |
| 2 | Photos | PDF, 3 pages | View Download |
| 3 | Airframe and Engine Examination Report | PDF, 9 pages | View Download |
| 4 | Operators Statement | PDF, 1 page | View Download |
| 5 | Maintenance Records | PDF, 8 pages | View Download |
| 6 | 24-035 Materials Lab Factual Report (WPR23LA350) | PDF, 9 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.