Grumman-Schweizer G-164B accident near Shelley, Idaho, July 4, 2002
On July 4, 2002 at about 2:30 am local time, a Grumman-Schweizer G-164B, registered N297AL, was destroyed in an accident near Shelley, Idaho. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loss of engine power due to the manufacturer's improperly machined threads, which prevented the cylinder base/head halves from being properly assembled, leading to fatigue propagation and the ultimate separation of the cylinder. A contributing factor was the rough terrain.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 4, 2002 · about 2:30 am local time
- Place
- Shelley, Idaho · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman-Schweizer G-164B
- Registration
- N297AL · registry record · serial 188B
- Damage
- Destroyed
- 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 commenced a spray run when there was an abrupt loss of power accompanied by engine roughness and vibration. Unable to maintain flight, the pilot executed a forced landing into the field being sprayed, landing across the rough, furrowed terrain. Post crash examination revealed that the top of the number five cylinder had separated from the lower half of the cylinder. Further metallurgical examination revealed that the cylinder split circumferentially due to fatigue which originated at the first and second thread roots of the cylinder threads on the inside of the cylinder head. Dimensional examination revealed that the threads between the cylinder base and head had been improperly machined resulting in the cylinder's abutting surfaces not coming into complete contact during assembly of the two components.
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: multi-engine land; single-engine land; instrument: airplane
- Flight time: 6,000 hours in all; 2,800 in this make and model; 120 in the last 90 days; 60 in the last 30 days; 5,800 as pilot in command
- Last flight review: January 20, 2002
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: frt
- Injury: minor injuries
The aircraft
- Airframe total time: 6,500 hours
- Last inspection: annual inspection, May 1, 2002; 120 hours since
- Maximum gross weight: 7,020 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt & Whitney R-1340 (piston); 0 hours total
The flight
- Departed from: Shelley ID at 2:10 am
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 170° at 8 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 39°F (4°C)
- Altimeter: 30.03 inHg
- Observation at 2:53 am from IDA, 5 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.