Air Tractor AT-401 accident near San Joaquin, California, July 26, 1990
On July 26, 1990 at about 7:30 am local time, a Air Tractor AT-401, registered N7315S, was substantially damaged in an accident near San Joaquin, California. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE FAILURE OF THE NO. 4 CYLINDER HEAD.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 26, 1990 · about 7:30 am local time
- Place
- San Joaquin, California · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Air Tractor AT-401
- Registration
- N7315S · no longer on the register · serial 401-0673
- 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 EXPERIENCED AN ENGINE FAILURE DURING AERIAL APPLICATION, LANDED IN A FIELD AND THE AIRCRAFT FLIPPED OVER. THE AIRCRAFT REMAINED INTACT WITH NO FIRE. THE PILOT EXPIRED FROM 'POSITIONAL ASPHYXIA.' EXAMINATION OF THE ENGINE REVEALED THE NO. 4 CYLINDER WAS CRACKED AROUND THE COOLING FINS AND CONTINUED THROUGH THE CENTER OF THE SPARK PLUG BOSS. THE ENGINE HAD 7251 TOTAL HOURS AND 339 HOURS SINCE OVERHAUL.
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: commercial pilot
- Ratings: single-engine land
- Flight time: 16,500 hours in all; 8,000 in this make and model; 175 in the last 90 days; 100 in the last 30 days; 16,500 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: ctr
The aircraft
- Airframe total time: 1,682 hours
- Last inspection: annual inspection, April 11, 1990; 249 hours since
- Maximum gross weight: 6,000 lb
- Seats: 1
- Landing gear: fixed
- Engine: P&W R1340-AN-1 (piston); 0 hours total
- Operator: Grouleff Aviation, INC.
The flight
- Destination: CA
- Flight plan: none
- Runway 0
Weather at the time
- Light: night, dark
- Wind: from 310° at 9 knots
- Visibility: 20 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 46°F (8°C)
- Altimeter: 29.00 inHg
- Observation at 6:50 am from FAT, 25 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.