Accident Overview
On March 16, 2022, about 1556 eastern daylight time, an Aeronca 11AC, N9588E, was substantially damaged when it was involved in an accident near Harveysburg, Ohio. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Flight Preparation
Before the flight, the instructor met with his new student at Warren County Airport / John Lane Field (I68), Lebanon, Ohio. They discussed the instructional flight objectives, focusing on aircraft familiarization and basic control coordination. A preflight inspection was conducted. The airplane had flown about 3.7 hours just before the accident flight. The instructor added 10 gallons of automotive premium 93 octane fuel containing ethanol to the airplane, which had a supplemental type certificate (STC) for automotive fuel. The fuel was screen-filtered through a funnel. The oil level was confirmed at 4 quarts, and the instructor showed the student how to sample fuel, confirming no water or debris. All other inspections indicated the aircraft was ready for flight.
Flight and Power Loss
After about 10 minutes of ground handling instruction around the ramp, they proceeded to the run-up area. Using the CIGAR checklist, the instructor conducted the run-up. All checks indicated readiness. They departed runway 19 about 1500. The instructor performed the takeoff and initial climb to 2,500 ft msl with an eastbound turn. Once established, the student handled the flight controls, maintaining heading while climbing to 3,000 ft msl. The instructor then gave instruction in basic flight maneuvers including shallow turns. After several maneuvers, they descended to 2,500 ft msl. While flying straight and level over Caesars Creek Lake in class E airspace, the engine sustained a severe loss of power. The instructor took the controls, pitched for best glide speed of 55-60 mph, and observed oil temperature and pressure gauges normal. The fuel gauge indicated full. He worked the throttle in and out with no effect, then pulled the carburetor heat on. The propeller continued windmilling without power.
Water Landing and Rescue
Realizing the engine would not recover, the instructor evaluated landing options. He chose to land on the water near the bank, avoiding the tree line. He instructed the student to brace for impact and expect the plane to flip. As they glided a few feet over the water, he held the airplane off until minimum controllable airspeed, then pulled back on the stick to drag the tailwheel through the water. However, when the main wheels contacted the water, the airplane nosed over, coming to rest on the leading edge of the wing, windscreen, propeller, and spinner, resulting in substantial damage. Both occupants exited and waded waist-high water to shore without injury. The instructor called 911, rescue arrived about 15 minutes later. An Ohio Department of Natural Resources boat transferred them to medical services, but both declined further aid and were driven to a marina by the Ohio State Highway Patrol.
Postaccident Examination
Postaccident examination of the airplane and engine did not reveal any evidence of preimpact failures or malfunctions that would have precluded normal operation.
Fuel and Placards Information
Examination of FAA records showed the airplane and engine had an STC for automotive gasoline. The flight instructor stated he did not know that premium automobile gasoline containing ethanol should not be used. The placards required by the STC were not present. According to the STC holder, ethanol should not be used in the airplane; pilots should use 100LL aviation fuel if ethanol-free gasoline is unavailable. The STC holder advised that ethanol fuels can damage rubber and aluminum components, increase fuel volatility, absorb water, and may vent off at altitude. Ethanol can pull moisture from air on humid days, potentially causing engine malfunction. Allowing ethanol gasoline to remain in the airplane for extended periods has led to replacement of carburetors, hoses, and gaskets, and can clean fuel tanks, depositing sludge in the fuel screen.
Carburetor Icing Considerations
According to Transport Canada TP 10737, fuels containing alcohol (methanol or ethanol) other than de-icing fluids are not permitted for use in aircraft. Alcohol can attack seal and fuel system rubbers and plastics. Alcohol and water mix; ethanol may separate from gasoline. Mogas (automotive gasoline) is generally higher in volatility than Avgas, absorbing more heat during vaporization and increasing ice accumulation at higher ambient temperatures. The likelihood of carburetor icing while flying on Mogas is higher, and its onset occurs at higher ambient temperatures and lower humidity. A carburetor icing probability chart indicated that meteorological conditions at the time of the accident were conducive to carburetor icing at glide and cruise power. FAA Special Airworthiness Information Bulletin CE-09-35 notes that carburetor icing can occur above freezing when visible moisture or high humidity is present, due to fuel vaporization and air expansion causing sudden cooling. A drop in rpm (fixed-pitch propeller) or manifold pressure (constant-speed propeller) indicates icing, often with engine roughness. Immediate application of full carburetor heat is recommended.