Air Tractor AT502 accident near Tappen, North Dakota, June 28, 2018
On June 28, 2018 at about 1:00 am local time, a 1997 Air Tractor AT502, registered N502S, was substantially damaged in an accident during takeoff near Tappen, North Dakota (Private airport). It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 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 partial loss of engine power for reasons that could not be determined based on the available evidence.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 28, 2018 · about 1:00 am local time
- Place
- Tappen, North Dakota · Private · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor AT502 B, built 1997
- Registration
- N502S · no longer on the register · serial 502B-0456
- 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 reported that he noticed degraded engine performance when the airplane was about halfway down the runway during takeoff for the aerial application flight. Specifically, the engine torque decreased from 1,700 ft-lbs at the start of the takeoff to 1,500 ft-lbs. He determined that there was not enough runway to abort the takeoff and stop the airplane, so he applied full power and dumped the product load. The engine continued to lose power, and the airplane subsequently continued off the end of the runway and nosed over in high vegetation. Postaccident examination of the airplane and engine, including individual testing of several engine components, confirmed that the engine was producing power during the impact sequence, but no determination could be made as to how much power the engine produced. The examination did not reveal any mechanical malfunctions or failures 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
- Loss of engine power (partial) during takeoff defining event
- Runway excursion during takeoff
- Nose over/nose down during takeoff
The NTSB's findings
- cause Not determined › Not determined › (general) › (general) › Unknown/Not determined
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instrument: airplane; rotorcraft: glider; rotorcraft: helicopter
- Flight time: 13,000 hours in all
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Last inspection: inspection type not recorded
- Maximum gross weight: 8,000 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt & Whitney Canada PT-6A-34AG (turboprop); 0 hours total
- Operator: Ross Seed Co Inc Dba
The flight
- Departed from: PVT Tappen ND at 1:00 am
- Destination: PVT Tappen ND
- Flight plan: none
- Runway 27, 2,500 ft by 100 ft
Weather at the time
- Light: daylight
- Wind: from 260° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 84°F (29°C), dew point 52°F (11°C)
- Altimeter: 29.81 inHg
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 December 5, 2019. 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 Statement | PDF, 1 page | View Download |
| 2 | Pratt & Whitney Examination Report | PDF, 63 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Other NTSB records under N502S the same tail number, which may have belonged to a different aircraft at the time
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.