Grumman G-164 accident near Nezperce, Idaho, April 5, 2004
On April 5, 2004 at about 3:00 pm local time, a Grumman G-164, registered N48564, was substantially damaged in an accident near Nezperce, Idaho. 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 circumferential fracture of the number seven cylinder head while en route to an aerial fertilizer application, leading to a forced landing on soft terrain, resulting in the collapse of the right main gear leg. Factors include soft terrain at the location where the pilot found it necessary to attempt the forced landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 5, 2004 · about 3:00 pm local time
- Place
- Nezperce, Idaho · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman G-164 · all G-164s on the register
- Registration
- N48564 · no longer on the register · serial 1675
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
While en route to apply dry fertilizer to a field, the aircraft's engine popped and then experienced a significant loss of power. Because there was not sufficient power to keep the aircraft airborne, the pilot elected to execute a forced landing in a nearby field. He therefore started dumping his load of fertilizer, and attempted to set the aircraft down on the soft terrain. Although the touchdown was successful, soon thereafter the main gear sank into the soft terrain, and the right main gear leg folded aft. As the gear leg collapsed, the nose and right wing of the aircraft impacted the terrain. A post-accident inspection of the engine revealed that the head of the number seven cylinder had fractured circumferentially just above the location where the head screws into the cylinder barrel. Although the head had not separated from the barrel, the fracture was far enough around the barrel that it created a misalignment of the cylinder geometry to an extent that the intake valve would not close. There was no indication of detonation or any other anomaly that would have been expected to apply greater than normal loads to the cylinder structure.
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: 5,653 hours in all; 3,768 in this make and model; 5,653 as pilot in command
- Last flight review: October 30, 2003
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: frt
- Injury: no injuries
The aircraft
- Airframe total time: 7,525 hours
- Last inspection: annual inspection, March 30, 2004; 33 hours since
- Maximum gross weight: 4,500 lb
- Seats: 1
- Landing gear: fixed
- Engine: Pratt & Whitney R1340-AN-1 (piston); 0 hours total
The flight
- Departed from: 0S5 Nezperce ID at 3:10 pm
- Destination: 0S5
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 50°F (10°C), dew point 0°F (-18°C)
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.
Other NTSB records under N48564 the same tail number, which may have belonged to a different aircraft at the time
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.