Mooney M20J accident near Oakley, Idaho, September 30, 2002
On September 30, 2002 at about 10:30 pm local time, a Mooney M20J, registered N4232H, was substantially damaged in an accident near Oakley, Idaho. It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Failure (fracture) of the two number four piston compression rings, leading to the erosion of a section of the piston sidewall, resulting in the exhaustion of the engine's oil supply during cruise flight, followed by a forced landing on a country road. Factors include mail boxes mounted on metal poles immediately adjacent to the side of the road.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 30, 2002 · about 10:30 pm local time
- Place
- Oakley, Idaho · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Mooney M20J · all M20Js on the register
- Registration
- N4232H · registry record · serial 24-0671
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During cruise flight, the aircraft began to lose oil pressure, and the propeller rpm stopped responding to the position of the propeller governor control lever. Eventually the engine oil pressure dropped to zero, and the pilot elected to attempt a forced landing on a country road. Although the touchdown was successful, during the landing roll, the aircraft's wings collided with mailboxes mounted on steel poles situated immediately adjacent to the side of the road. It was later determined that both compression rings on the number four piston had failed (fractured), and that a portion of the piston outer wall near the piston dome had eroded away allowing loss of a majority of the engine's oil through the engine exhaust system.
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: private
- Ratings: single-engine land; instrument: airplane
- Flight time: 5,647 hours in all; 3,707 in this make and model; 20 in the last 90 days; 14 in the last 30 days; 5,516 as pilot in command
- Last flight review: August 24, 2001
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 3,971 hours
- Last inspection: annual inspection, September 16, 2002; 12 hours since
- Maximum gross weight: 2,740 lb
- Seats: 4
- Landing gear: retractable
- Engine: Lycoming IO-360-A3B6D (piston); 0 hours total
The flight
- Departed from: GJT Grand Junction CO at 8:00 pm
- Destination: BOI Boise ID
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: scat at 6,000 ft
- Temperature: 55°F (13°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.