Grumman Acft Eng Cor-Schweizer G-164B accident near Garrison, North Dakota, July 9, 2014
On July 9, 2014 at about 8:00 pm local time, a 1977 Grumman Acft Eng Cor-Schweizer G-164B, registered N6648Q, was substantially damaged in an accident during maneuvering (low-alt flying) near Garrison, North Dakota. 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
Excessive wear between the power turbine shaft and quill shaft spline, which led to the disconnection of the power turbine wheel, an overspeed of the power turbine, and the subsequent loss of engine power. Contributing to the accident was maintenance personnel’s failure to detect contaminants in the oil filter during the engine’s recent 100-hour inspection.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 9, 2014 · about 8:00 pm local time
- Place
- Garrison, North Dakota · 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-164B, built 1977 · all G-164Bs on the register
- Registration
- N6648Q · registry record · serial 175B
- 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 was spraying fungicide on a field when the engine lost power and that he then observed white smoke coming from the exhaust stacks. He feathered the propeller, shut the fuel off, and landed the airplane in a wheat field. The airplane struck a barbed wire fence before coming to a stop, which resulted in substantial damage to the forward fuselage. The examination of the turboprop engine revealed that wear between the power turbine shaft and the quill shaft had led to the disconnection of the power turbine wheel, an overspeed of the power turbine, and a subsequent loss of engine power. During postaccident examination, a considerable amount of extremely fine black particles were found in the oil filter, consistent with excessive spline wear, which appeared to have been occurring for some time. Maintenance records indicated that the last 100-hour inspection of the engine was accomplished 2 days before the accident. It is likely that maintenance personnel did not examine the oil filter during that inspection. If they had examined the oil filter, they would have detected the contaminants, which would have indicated an impending failure of an internal engine component. There have been five similar events involving the same make and model engine, and the manufacturer issued a service bulletin with instructions for inspecting the engine; the Federal Aviation Administration subsequently issued a notice of proposed rulemaking to require the inspection.
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
- Off-field or emergency landing during emergency descent
- Landing gear collapse during landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Turbine section › Failure
- factor Personnel issues › Action/decision › Action › Forgotten action/omission › Maintenance personnel
- factor Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Turbine section › Inadequate inspection
- factor Personnel issues › Task performance › Inspection › Scheduled/routine inspection › Maintenance personnel
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land
- Flight time: 1,200 hours in all; 800 in this make and model; 200 in the last 90 days; 100 in the last 30 days; 1,000 as pilot in command
- Last flight review: April 25, 2014
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: sngl
- Injury: no injuries
The aircraft
- Airframe total time: 8,691 hours
- Last inspection: annual inspection, May 17, 2014; 9 hours since
- Maximum gross weight: 5,822 lb
- Seats: 1
- Landing gear: fixed
- Engine: Williams M601-11 (turboprop); 1,675 hours total
The flight
- Departed from: D05 Garrison ND at 7:00 pm
- Destination: D05 Garrison ND
- Flight plan: VFR
Weather at the time
- Light: daylight
- Sky: clear
- Temperature: 70°F (21°C), dew point 55°F (13°C)
- Observation at 7:00 pm from D60, 8 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.