Grumman G-164A accident near Fergus Falls, Minnesota, July 20, 2012
On July 20, 2012 at about 1:00 am local time, a Grumman G-164A, registered N4638, was substantially damaged in an accident during maneuvering (low-alt flying) near Fergus Falls, Minnesota. 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
A total loss of engine power due to a cracked No. 2 cylinder head.
Source: NTSB aviation accident database, copy made November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 20, 2012 · about 1:00 am local time · cases in 2012
- Place
- Fergus Falls, Minnesota · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman G-164A · all G-164As on the register
- Registration
- N4638 · no longer on the register · serial 1071
- 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 was spraying a large corn field when he saw a puff of white smoke come from the engine. He turned toward a road, but about half way through the turn, the engine lost all power. The pilot jettisoned the chemical load and landed in the corn field. Examination of the radial engine revealed the No. 2 cylinder head was cracked. A review of the maintenance logbooks revealed that a mandatory Federal Aviation Administration Airworthiness Directive that required a 100-hour visual inspection to prevent cylinder head cracking, had been complied with at the last annual inspection, but no entries were made that any cracks were observed.
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 (total) during maneuvering (low-alt flying) defining event
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Failure other cases naming the engine
- Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Maintenance personnel
- Personnel issues › Task performance › Inspection › Scheduled/routine inspection › Maintenance personnel
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 1,851 hours in all; 829 in this make and model; 240 in the last 90 days; 130 in the last 30 days; 1,814 as pilot in command
- Last flight review: April 28, 2011
- Medical certificate: Class 2
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 9,012 hours
- Last inspection: annual inspection, March 17, 2012
- Maximum gross weight: 4,500 lb
- Seats: 1
- Landing gear: fixed
- Engine: P&W R1340 SERIES (piston); 0 hours total
- Operator: West Central Ag-Air INC
The flight
- Departed from: ETH Wheaton MN
- Destination: Dumont MN
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
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 July 22, 2013. 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/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 14 pages | View Download |
| 2 | Record of Conversation - FAA Inspector | PDF, 1 page | 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 N4638 the same tail number, which may have belonged to a different aircraft at the time
Connections how this case links to the rest of the register
- N4638: not on the register today · the record of its deregistration
- Grumman G-164 119 registered today · the model family and its accident history
- Grumman 443 aircraft on the register
- Engine: P&W R1340 SERIES 1,229 aircraft carry this series today · as the NTSB recorded it
- Wheaton Municipal · departed from
- Accidents and incidents in Minnesota 1,544 since 1982 · 209 in the last ten years
- Minnesota 6,953 aircraft registered
- Other NTSB records under N4638 1 records · the number may have belonged to another aircraft at the time
The whole map of how records connect · these connections as data: /graph/accident/CEN12LA491.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
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 does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.