Amateur-built Experimental Cub accident near Stanley, Idaho, June 13, 2019
On June 13, 2019 at about 7:20 pm local time, a 2013 amateur-built Experimental Cub, registered N9WU, was substantially damaged in an accident during enroute (cruise) near Stanley, Idaho. It was a personal flight under general aviation rules (Part 91). 2 people were seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Overstress failure of the right-wing spar due to an encounter with turbulence.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 13, 2019 · about 7:20 pm local time
- Place
- Stanley, Idaho · map
- Type
- Accident
- Injuries
- 2 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built Experimental Cub, built 2013
- Registration
- N9WU · registry record · serial 0003
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While overflying mountainous terrain, the airplane encountered turbulence. The pilot heard a “pop” from the right wing and shortly thereafter, the wing began to shake violently. The pilot was maneuvering the airplane to a forced landing site when the airplane encountered turbulence again and subsequently entered a spin that continued until impact with terrain. The accident site was adjacent to a mountain range where strong thermals likely existed as well as an unstable low-level pressure system. This is likely the cause of the localized turbulence that was encountered by the flight. Examination of the wing spar revealed in-plane fractures consistent with tensile overstress failure. The fracture sequence started with the fracture of the wing spar, which led to subsequent spar fractures, and eventual buckling and fracture of the connected supporting members and struts. It is likely that the turbulence encounter resulted in excessive loads on the wing and subsequent overstress failure.
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
- Turbulence encounter during enroute (cruise) defining event
- Loss of control in flight during enroute (cruise)
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Environmental issues › Conditions/weather/phenomena › Turbulence › Terrain induced turbulence › Effect on equipment
- cause Aircraft › Aircraft structures › Wing structure › Spar (on wing) › Failure
Pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; multi-engine sea; single-engine land; single-engine sea; instrument: airplane
- Flight time: 30,450 hours in all; 1,000 in this make and model
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: serious injuries
Passenger
- Seat: rgt
- Injury: serious injuries
The aircraft
- Last inspection: condition inspection
- Landing gear: fixed
- Engine: Lycoming O-320-B2C (piston); 0 hours total
The flight
- Departed from: BYI Burley ID
- Destination: 3U2 Yellow Pine ID
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 72°F (22°C), dew point 41°F (5°C)
- Altimeter: 30.11 inHg
- Observation at 6:48 pm from SNT, 2 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number WPR19LA170.