Air Tractor AT-502B accident near Rigby, Idaho, August 20, 2002
On August 20, 2002 at about 12:52 pm local time, a Air Tractor AT-502B, registered N6146G, was substantially damaged in an accident near Rigby, Idaho (Rigby-Jefferson County airport). It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The failure of one or more compressor turbine blades resulting in a shutdown of the engine during initial climb resulting in a forced landing. Contributing factors were the eroded condition of the compressor turbine guide vane nozzles and the ditch which the aircraft encountered during the landing rollout.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 20, 2002 · about 12:52 pm local time
- Place
- Rigby, Idaho · Rigby-Jefferson County · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor AT-502B
- Registration
- N6146G · no longer on the register · serial 502B-0299
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the Air Tractor AT-502B had reported observing no abnormalities during engine start and the subsequent application of power during takeoff. Climbing through 100 feet he heard a loud "bang," observed sparks and flames exiting the engine exhaust ports and transitioned to a power off forced landing. As the aircraft was rolling out it encountered a ditch and the main landing gear separated. Post-crash examination of the engine revealed extensive damage to the blades of the compressor turbine disk and erosive burning damage to the vanes of the vane ring situated immediately upstream of the compressor turbine disk. The 22 year old Pratt & Whitney PT6A-34 turboshaft engine had a total of 7,070 hours since new and had undergone an undocumented overhaul 5,820 hours previously to the accident. The last hot section inspection referenced in the engine log occurred 2,871 hours previous to the accident and the last logged inspection was a 100-hour inspection 324 hours and eight months previous to the accident.
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: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 2,256 hours in all; 294 in this make and model; 260 in the last 90 days; 86 in the last 30 days; 2,187 as pilot in command; 251 on instruments
- Last flight review: May 17, 2001
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: frt
- Injury: minor injuries
The aircraft
- Last inspection: 100-hour inspection, December 20, 2001
- Maximum gross weight: 9,700 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt & Whitney Canada PT6A-34 (turboprop); 0 hours total
The flight
- Departed from: U56 Rigby ID at 12:50 pm
- Flight plan: none
- Runway 19, 3,500 ft by 50 ft
Weather at the time
- Light: daylight
- Wind: from 190° at 14 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 14,000 ft
- Temperature: 61°F (16°C), dew point 34°F (1°C)
- Altimeter: 29.81 inHg
- Observation at 12:53 pm from IDA, 10 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 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.
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.