Accident Overview
On July 4, 2024, at 1600 eastern daylight time, a Bellanca 8GCBC (registration N749SK) was substantially damaged when it struck trees near Frankford, Delaware. The commercial pilot on board sustained minor injuries. The airplane was being operated as a Title 14 CFR Part 91 banner towing flight.
Preflight and Previous Flights
The airplane was based at Bunting's Field Airport (4MD1) in Berlin, Maryland. Prior to the first flight of the day, the pilot added one quart of oil to the engine and performed a preflight inspection, noting no abnormalities. Fuel was added and an engine run-up was normal. The pilot then conducted several aerial advertising banner flights throughout the day, adding fuel as needed, all without incident.
Accident Flight
During the accident flight, the pilot towed a banner from 4MD1 to the Ocean City, Maryland inlet at 1,000 feet mean sea level (msl), then descended to 300 ft msl and flew north along the Rehoboth Beach coast for advertising. The flight was uneventful with engine indications and airplane performance normal and “in the green.” However, toward the end of the route, engine oil temperature, usually about 190°F, indicated about 220° to 230°F.
The pilot reported this higher oil temperature to the operator, who stated it was within limits given the hot outside air temperature. As the pilot neared the end of the advertising portion, he initiated a climb to 1,200 ft msl, but the airplane would not maintain altitude despite full throttle and mixture controls.
Power Loss and Forced Landing
The airplane slowly descended while engine rpm dropped and engine roughness increased in severity. At 700 ft msl, the pilot released the banner over a vacant field. At 500 ft msl, the engine power further reduced. The pilot aimed for a forced landing in a field but was unable to reach it; the aircraft struck the top of trees. It then descended inverted to the ground, resulting in substantial damage to the wings and airframe.
Post-Accident Examination
Examination of the airframe and engine found fuel and oil present. The crankshaft rotated via the propeller, and crankshaft and valvetrain continuity were confirmed. Compression was present on all cylinders. Erosion damage was noted on the edge of the No. 3 cylinder intake valve and valve seat insert, along with a cracked lower spark plug. Maintenance records showed the No. 3 cylinder assembly was replaced with a new cylinder during an annual inspection 45 days before the accident. The airplane was subsequently signed off as airworthy.