Cessna 172N accident near Flat Rock, Virginia, February 17, 2012
On February 17, 2012 at about 9:52 pm local time, a Cessna 172N, registered N4737D, was substantially damaged in an accident during enroute (cruise) near Flat Rock, Virginia. It was a personal flight under general aviation rules (Part 91). 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 partial loss of engine power due to the failure of the exhaust valve spring seat for reasons that could not be determined.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 17, 2012 · about 9:52 pm local time
- Place
- Flat Rock, Virginia · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 172N · all 172Ns on the register
- Registration
- N4737D · no longer on the register · serial 17272345
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
According to the pilot, while in cruise flight, the engine began to lose power. He noticed a vibration in the throttle control and an “oily” smell. Engine power decreased to 1,500 rpm. The airplane was unable to maintain altitude, and the pilot elected to make an emergency landing in a field. During the landing roll, the airplane collided with an embankment and sustained substantial damage to the fuselage. An examination of the engine revealed that the No. 4 valve spring seat had broken. A review of the maintenance records revealed that the engine had accumulated 1865.34 hours since the last overhaul 6.5 years before the accident. According to Lycoming Service Instruction 1009AU, the recommended time between overhaul is 2,000 hours or 12 years, whichever occurs first. Further review of the maintenance records revealed compliance with Airworthiness Directive 80-04-03 R2, which covers the replacement of the upper exhaust valve spring seats and the exhaust hydraulic lifters. The exhaust valve seat failed 134.66 hours before the next recommended overhaul. The investigation was unable to determine the reason for the valve seat failure.
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
What happened, in order
- Loss of engine power (partial) during enroute (cruise) defining event
- Off-field or emergency landing during emergency descent
- Collision during takeoff/land during landing (landing roll)
The NTSB's findings
- cause Not determined › Not determined › (general) › (general) › Unknown/Not determined
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane
- Flight time: 783 hours in all; 767 in this make and model; 20 in the last 90 days; 1 in the last 30 days; 669 as pilot in command
- Medical certificate: Class 3 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 1,557 hours
- Last inspection: annual inspection, June 20, 2011; 11 hours since
- Maximum gross weight: 2,400 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming 0-320 SERIES (piston); 0 hours total
The flight
- Departed from: HEF Manassas VA at 8:49 pm
- Destination: FAY Fayetteville NC
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 150° at 3 knots
- Visibility: 4 statute miles
- Sky: broken clouds at 9,000 ft; scat at 5,500 ft
- Temperature: 45°F (7°C), dew point 43°F (6°C)
- Altimeter: 30.06 inHg
- Observation at 9:54 pm from OFP, 24 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.