Grumman Acft Eng Cor-Schweizer G-164A accident near Wilton, California, May 27, 2012
On May 27, 2012 at about 3:15 pm local time, a Grumman Acft Eng Cor-Schweizer G-164A, registered N8380, was substantially damaged in an accident during maneuvering (low-alt flying) near Wilton, California (Clarksburg 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 failure of the hopper gate mechanism and subsequent sulfur fire during a low-level maneuver.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 27, 2012 · about 3:15 pm local time
- Place
- Wilton, California · Clarksburg · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman Acft Eng Cor-Schweizer G-164A · all G-164As on the register
- Registration
- N8380 · no longer on the register · serial 874
- 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 had just completed an aerial application of sulfur dust over a vineyard when the hopper gate closing mechanism failed as he attempted to stop the flow. The sulfur continued to flow from the hopper, so he initiated a steep turn to keep the dust within the confines of the vineyard. As he rolled out of the turn, the plume of sulfur ignited and a fire began within the hopper. He performed a forced landing into a residential driveway and the airplane sustained substantial damage during the ground roll. The airplane was configured to minimize the hazards of inadvertent fire during sulfur dusting operations; however, the evasive flight maneuver performed by the pilot may have brought the uninterrupted flow of sulfur dust into contact with hot engine exhaust. An alternative ignition source may also have been provided by a spark from the failed gate mechanism. The gate mechanism sustained thermal damage, which prevented an accurate assessment of its failure mode.
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
- Sys/Comp malf/fail (non-power) during maneuvering (low-alt flying) defining event
- Hazardous material leak/spill during maneuvering (low-alt flying)
- Abrupt maneuver during maneuvering (low-alt flying)
- Fire/smoke (non-impact) during maneuvering (low-alt flying)
- Off-field or emergency landing during emergency descent
- Collision with terrain or object (not controlled flight into terrain) during landing (landing roll)
The NTSB's findings
- cause Aircraft › Aircraft systems › Equipment/furnishings › Agricultural/external load sys › Failure
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 3,300 hours in all; 2,000 in this make and model; 100 in the last 90 days; 30 in the last 30 days; 3,200 as pilot in command
- Last flight review: June 1, 2010
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Airframe total time: 12,376 hours
- Last inspection: annual inspection, January 16, 2012; 56 hours since
- Maximum gross weight: 4,500 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt And Whitney R1340 SERIES (piston); 0 hours total
The flight
- Departed from: PVT Clarksburg CA at 2:45 pm
- Destination: PVT Wilton CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 180° at 6 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 1,500 ft
- Temperature: 55°F (13°C), dew point 46°F (8°C)
- Altimeter: 30.12 inHg
- Observation at 3:45 pm from KMHR, 15 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.