Cessna 172M accident near Coolin, Idaho, September 7, 1994
On September 7, 1994 at about 8:00 pm local time, a Cessna 172M, registered N61838, was substantially damaged in an accident near Coolin, Idaho. It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries; 2 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE FAILURE OF THE ENGINE MANUFACTURER TO PROPERLY REMANUFACTURE AND ADEQUATELY INSPECT THE NO. 1 ROCKER ARM PRIOR TO ITS INSTALLATION ON THE ENGINE. THIS RESULTED IN FATIGUE CRACKING OF THE ROCKER ARM AND A SUBSEQUENT LOSS OF ENGINE POWER.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 7, 1994 · about 8:00 pm local time
- Place
- Coolin, Idaho · map
- Type
- Accident
- Injuries
- 1 person had minor injuries; 2 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 172M · all 172Ms on the register
- Registration
- N61838 · no longer on the register · serial 17264832
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE PRIVATE PILOT WAS FORCED TO LAND THE AIRPLANE ON UNSUITABLE TERRAIN BECAUSE OF A LOSS OF ENGINE POWER. DURING THE FORCED LANDING, THE AIRPLANE IMPACTED A TREE STUMP, NOSED OVER, AND WAS SUBSTANTIALLY DAMAGED. AN EXAMINATION OF THE ENGINE REVEALED THAT THE ROCKER ARM FOR THE NO. 1 CYLINDER EXHAUST VALVE HAD FAILED. AN EXAMINATION OF THE ROCKER ARM REVEALED THAT THE ARM HAD FAILED DUE TO FATIGUE, AND THAT THE FATIGUE CRACKING WAS INITIATED AT ROUGH TOOL MARKS PRODUCED DURING THE CHAMFERING OF THE ARM'S OIL HOLE. THE CHAMFERING WAS PERFORMED BY THE ENGINE MANUFACTURER DURING REMANUFACTURE OF THE ENGINE.
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
- Flight time: 202 hours in all; 200 in this make and model; 53 on instruments
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 2,263 hours
- Last inspection: annual inspection, May 4, 1994; 15 hours since
- Maximum gross weight: 2,400 lb
- Seats: 0
- Landing gear: fixed
- Engine: Lycoming O-320-E2D (piston); 0 hours total
The flight
- Departed from: 66S Cavinaugh Bay ID at 7:15 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 170° at 4 knots
- Visibility: 30 statute miles
- Sky: ovct at 25,000 ft
- Temperature: 82°F (28°C), dew point 37°F (3°C)
- Altimeter: 29.00 inHg
- Observation at 7:52 pm from GEG, 25 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 2 |
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.