Cessna 172 accident near Oloh, Mississippi, November 25, 2017
On November 25, 2017 at about 8:55 pm local time, a 1978 Cessna 172, registered N739KW, was substantially damaged in an accident during enroute (cruise) near Oloh, Mississippi. 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
A partial loss of engine power due to the failure of the No. 3 valve key (exhaust).
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 25, 2017 · about 8:55 pm local time
- Place
- Oloh, Mississippi · map
- Type
- Accident
- Injuries
- 1 person had minor injuries; 2 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 172 N, built 1978 · all 172s on the register
- Registration
- N739KW · no longer on the register · serial 17270613
- 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, while the airplane was about 3,500 ft above mean sea level, the engine produced a "very rapid metallic banging/clanging noise," along with an instant loss of engine rpm. The engine was creating a "violent shaking" of the entire airframe. After about 20 seconds of applying carburetor heat, the pilot applied full mixture and started adjusting the throttle to obtain more power. He reported that, with more power applied, the shaking became more violent, along with a loss of engine rpm. The pilot realized that the engine power at this point was not sufficient to hold altitude. During a forced landing to a field, both wings and the fuselage sustained substantial damage. Examination of the airframe and propeller found no preimpact mechanical malfunctions or failures that would have precluded normal operation. Examination of the engine revealed the No. 3 piston area displayed internal impact marks from the piston impacting the exhaust valve. The No. 3 exhaust valve was open and displayed impact marks from contact with the piston. The No. 3 valve spring seat (upper exhaust) was impact damaged with fractured pieces of the valve key (exhaust) and the valve stem cap (exhaust) laying on the bottom of the rocker area of the cylinder head. The No. 3 exhaust valve assembly moved freely inside the valve seats and was contacting the top of the piston. Based on the available evidence, the partial loss of engine power was likely due to the No. 3 valve key (exhaust) failing, which resulted in a substantial reduction in engine power output. The reason for the failure was undetermined, as the service history of the valve key was unknown.
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
- Powerplant sys/comp malf/fail during enroute (cruise) defining event
- Loss of engine power (partial) during enroute (cruise)
- Attempted remediation/recovery during enroute (cruise)
- Off-field or emergency landing during landing
- Collision during takeoff/land during landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Failure
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Fatigue/wear/corrosion
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 82 hours in all; 38 in this make and model; 1 in the last 90 days; 1 in the last 30 days; 20 as pilot in command
- Last flight review: August 9, 2017
- Medical certificate: Class 3 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 1,945.0 hours
- Last inspection: 100-hour inspection, June 26, 2017
- Maximum gross weight: 2,300 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming Engines O-320-H2AD (piston); 1,973 hours total
The flight
- Departed from: MCB Mc Comb MS at 8:05 pm
- Destination: HBG Hattiesburg MS
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 190° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 68°F (20°C), dew point 37°F (3°C)
- Altimeter: 30.01 inHg
- Observation at 8:53 pm from KHBG, 17 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
5 documents, released by the NTSB on March 19, 2020. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Maintenance Records | PDF, 4 pages | View Download |
| 3 | Lycoming Engines Illustrated Parts Catalog Excerpt | PDF, 2 pages | View Download |
| 4 | Statement of Party Representatives to NTSB Investigation | PDF, 1 page | View Download |
| 5 | Accident Photographs | PDF, 10 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.