Incident Overview
On November 2, 2016, at approximately 1100 eastern daylight time, an Aviat Aircraft Inc. A-1B, registration N54HY, was substantially damaged after striking a fence during a precautionary landing near Geneva, Florida. The commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the banner tow flight, which was conducted under 14 Code of Federal Regulations Part 91.
Flight History
The flight departed from Massey Ranch Airpark (X50) in New Smyrna Beach, Florida, around 1050, en route to Orlando Executive Airport (ORL). The pilot reported performing an engine run-up prior to departure with no anomalies. Approximately 10 minutes into the flight, the engine began to run rough. Despite adjustments to the throttle, propeller lever, mixture, and carburetor heat, the engine started to backfire and continued losing power. The pilot observed a racetrack below and elected to perform a precautionary landing. He spiraled down from about 1,000 feet above ground level to warn personnel on the track and maneuvered to land on a paved area. During the landing roll, the aircraft struck a fence and came to rest. The pilot stated that the engine continued operating until the fence impact.
Aircraft and Engine Details
According to FAA records, the aircraft received its airworthiness certificate in 2001. It was equipped with a Lycoming O-360-A1P, 180-horsepower engine. The airframe maintenance logbook showed the most recent annual inspection occurred on September 3, 2016, at a total time of 4,571.3 hours. At the time of the accident, the airframe total time was 4,650.3 hours.
Examination Findings
Post-accident examination revealed substantial damage to the left wing. An undetermined amount of fuel was removed during recovery. Engine crankshaft continuity was confirmed from the propeller to the accessory drive. Inspection of spark plugs showed mechanical damage to the No. 1 cylinder's top and bottom spark plug electrodes, which had become displaced and shorted to the center electrode. No mechanical damage was noted on other spark plugs. Additionally, the No. 1 piston appeared sandblasted compared to other cylinders. The left magneto generated spark on all towers, while the right magneto sparked on only one tower.
Recent maintenance on October 31, 2016, addressed hard starting, low static RPM, and rough engine operation. The maintenance entry indicated both No. 1 spark plugs were damaged; eight new spark plugs were installed, after which test runs showed smooth magneto drops and satisfactory leak and operational checks.
Photographs of the No. 1 spark plugs removed on October 31, 2016, showed absent ceramic material around the massive electrode and mechanical damage to the center and ground electrodes. Comparison of those photographs with the spark plugs removed after the accident flight revealed similar mechanical damage to the No. 1 cylinder spark plugs.
Further engine disassembly under FAA oversight examined the intake system, carburetor box, carburetor, exhaust system, and No. 1 cylinder; no debris was found inside these components.