Accident Sequence
On October 22, 2023, at about 1515 eastern daylight time, a Piper PA-24-250 airplane, registration N6757P, was substantially damaged when it came to rest upright in a cornfield near Ottawa, Ohio. The private pilot reported minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
The pilot stated that he departed from Abrams Municipal Airport (4D0), Grand Ledge, Michigan, with full fuel tanks (about 60 gallons) intending to fly to Pompano Beach Airpark (PMP), Pompano Beach, Florida. About five minutes after takeoff, while observing sporadic clouds, he applied carburetor heat for about 30 seconds and the airplane "buffered a lot." Approximately 40 minutes into the flight, at an altitude of 6,700 ft msl, he noted a 5-inch drop in manifold pressure, prompting him to apply carburetor heat for about 90 seconds, during which the airplane "buffered really hard."
Between 1450 and 1506, the pilot applied carburetor heat at least four more times, each for about 30 seconds, while monitoring engine indications. At about 1507, with carburetor heat still engaged, he heard a bang and the airplane shuddered. The propeller and engine did not respond, and the engine lost all power. The pilot declared his intentions to air traffic control and searched for a landing area. Unable to find a road without powerlines or traffic, he landed in a flat field; after touchdown, the airplane entered a cornfield and came to rest upright. The pilot exited the airplane unassisted and was met by first responders.
Post-Accident Examination
A Federal Aviation Administration inspector responded to the accident site. The wreckage was upright in the cornfield with no fire. The fuselage and wings sustained substantial damage. The wreckage was moved to an aircraft storage facility for examination by an NTSB investigator.
The engine remained attached to the mount and firewall. External examination revealed no evidence of case rupture or oil leakage. Control continuity from cockpit controls to the carburetor and propeller was established. Fuel system gascolators were drained; one contained about 2 ounces of blue-colored fuel, the other about 1 ounce, both with trace amounts of gray particulates resembling sand.
Top spark plugs showed normal wear with light gray, lean coloring per a Champion Check-A-Plug chart. Internal engine continuity was confirmed by manually rotating the propeller; compression and suction were noted on all cylinders, and valve action was correct. Both magnetos produced spark to all leads when rotated manually.
The carburetor was removed and partially disassembled. The bowl was dry and clean, brass floats undamaged, and the inlet fuel screen unobstructed with a trace of light gray particulates resembling sand. The accelerator pump operated normally. The engine-driven fuel pump was unremarkable. Examination of the engine and fuel system did not reveal any anomaly or malfunction that would have prevented normal operation.
Carburetor Icing Information
FAA Special Airworthiness Information Bulletin (CE-09-35) – Carburetor Icing Prevention, states that carburetor icing can occur at temperatures above freezing due to fuel vaporization and air expansion (Venturi effect), causing sudden cooling. Ice can be detected by a drop in rpm in fixed-pitch propeller airplanes or a drop in manifold pressure in constant-speed propeller airplanes, often accompanied by engine roughness.
A review of the CE-09-35 carburetor icing probability chart indicated that the airplane was operated in conditions conducive to icing at glide and cruise power, and serious icing at glide power.