Cessna 172N accident near Orange Beach, Alabama, July 4, 2011
On July 4, 2011 at about 7:30 pm local time, a Cessna 172N, registered N109DP, was substantially damaged in an accident during enroute (cruise) near Orange Beach, Alabama. It was a banner-towing 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
The operation of the airplane using unapproved fuels, which resulted in abnormal combustion and subsequent damage to the No. 3 cylinder. Contributing to the accident was the inadequate 100-hour inspection because the mechanic failed to note the lack of placards by either fuel filler cap specifying the minimum automotive fuel grade and no alcohol allowed as specified by the installed STC’s.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 4, 2011 · about 7:30 pm local time
- Place
- Orange Beach, Alabama · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 172N · all 172Ns on the register
- Registration
- N109DP · no longer on the register · serial 17270607
- Damage
- Substantial damage
- Flight
- Banner-towing flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane had been modified by several Supplemental Type Certificates (STCs) allowing the use of 91 minimum octane alcohol-free fuel, or a combination of 100LL and 91 minimum octane ethanol-free fuel. After takeoff while operating the engine on a mixture of 100LL and 87 octane automotive fuels with 10 percent ethanol additive, the engine experienced abnormal combustion in the No. 3 cylinder, which burned a hole through the cylinder near the lower spark plug hole. The resulting loss of engine power necessitated a forced landing in water. Postaccident examination of the engine revealed no discrepancies with the power train, ignition, lubrication, or air induction systems that would have led to the event. Metallurgical examination of the No. 3 cylinder revealed no manufacturing defects that would have damaged to the cylinder. No placards were noted by either fuel cap; these were required by the installed STCs specifying minimum octane rating of 91 without alcohol; however, on the day of the accident, the airplane underwent a 100-hour inspection by the pilot-in-command who held a mechanic certificate with airframe and powerplant ratings and inspection authorization; he had also performed the modification allowing the airplane to use automotive fuel. Although no fuel samples were retained for testing, the damage to the cylinder was consistent with the usage of unapproved fuel with too low an octane rating.
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
- Ditching during emergency descent
- Nose over/nose down during landing (flare/touchdown)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Failure
- cause Aircraft › Fluids/misc hardware › Fluids › Fuel › Fluid type
- factor Aircraft › Aircraft handling/service › Maintenance/inspections › Scheduled maint checks › Inadequate inspection
- factor Aircraft › Aircraft handling/service › Placards and markings › (general) › Not serviced/maintained
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 7,164 hours in all; 500 in this make and model; 75 in the last 90 days; 25 in the last 30 days; 6,714 as pilot in command; 2,649 on instruments
- Last flight review: July 18, 2009
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: rgt
- Injury: no injuries
Other crew
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 2,453 hours in all; 32 in the last 90 days
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 2,927 hours
- Last inspection: 100-hour inspection, July 4, 2011; 2 hours since
- Maximum gross weight: 2,300 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-360-A4M (piston); 0 hours total
- Operator: Gulf Coast Aerial Advertising INC
The flight
- Departed from: 0AL1 Foley AL at 7:00 pm
- Destination: 0AL1 Foley AL
- Flight plan: none
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 160° at 8 knots, gusting 16
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 90°F (32°C), dew point 66°F (19°C)
- Altimeter: 29.96 inHg
- Observation at 7:35 pm from JKA, 7 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.