Boeing A75N1 accident near Medicine Bow, Wyoming, January 20, 1993
On January 20, 1993 at about 1:10 am local time, a Boeing A75N1, registered N56924, was substantially damaged in an accident near Medicine Bow, Wyoming. It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was conditions the NTSB did not record.
The NTSB's probable cause their words, unchanged
FAILURE OF THE #7 CYLINDER ROCKER ARM. FACTORS CONTRIBUTING TO THE ACCIDENT WERE UNSUITABLE TERRAIN AND DARK NIGHT CONDITIONS.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- January 20, 1993 · about 1:10 am local time
- Place
- Medicine Bow, Wyoming · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- conditions the NTSB did not record
- Aircraft
- Boeing A75N1 · all A75N1s on the register
- Registration
- N56924 · no longer on the register · serial 75-2480
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE PILOT REPORTED THAT SHORTLY AFTER LEVELLING OFF AT 14,000 FEET MSL, THE ENGINE SURGED THREE TIMES AND THEN STOPPED. A FORCED LANDING WAS EXECUTED ONTO ROCKY, UPSLOPING TERRAIN, UNDER DARK NIGHT CONDITIONS. SUBSEQUENT DISASSEMBLY OF THE ENGINE REVEALED THAT THE NUMBER 7 CYLINDER INTAKE VALVE ROCKER ARM HAD FAILED.
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: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane; rotorcraft: gyroplane
- Flight time: 9,999 hours in all; 9,999 in this make and model; 40 in the last 90 days; 9,999 as pilot in command; 1,429 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rear
The aircraft
- Airframe total time: 6,601 hours
- Last inspection: annual inspection, January 2, 1993; 10 hours since
- Maximum gross weight: 2,950 lb
- Seats: 2
- Landing gear: fixed
- Engine: P&W R-985-AN1 (piston); 0 hours total
The flight
- Departed from: RKS Rock Springs WY at 11:45 pm
- Destination: LAR Laramie WY
- Flight plan: none
- Runway 0
Weather at the time
- Light: night, dark
- Wind: from 250° at 14 knots
- Visibility: 7 statute miles
- Sky: overcast at 1,500 ft; scat at 800 ft
- Temperature: 25°F (-4°C), dew point 21°F (-6°C)
- Altimeter: 29.00 inHg
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.