N5700BCessna 182 · 1956

On May 27, 2018, about 1420 mountain daylight time, a Cessna 182 airplane, N5700B, sustained substantial damage when it was involved in an accident near Aberdeen, Idaho. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that, before the flight, he verified that 55 gallons of fuel were onboard for the 3-hour 3-minute-long flight. He typically planned for a fuel burn of about 12 gallons per hour. During the flight, he made two minor deviations from the intended flightpath due to weather. As the airplane passed Aberdeen Airport (U36), Aberdeen, Idaho, it encountered light drizzle and reduced visibility. After continuing for a few minutes in these conditions while about 2,000 ft above ground level, the pilot decided to initiate a right turn and divert from his original destination, Blackfoot Airport (U02), Blackfoot, Idaho, to Burley Municipal Airport (BIY), Burley, Idaho. As the airplane exited the turn, the engine “stuttered” a few times and eventually lost power. The pilot immediately began troubleshooting, but despite his attempts to restore engine power, it would only run roughly and inconsistently.

The pilot then chose to divert to U36 because it was closer to the airplane’s position, and as he was about to begin another attempt to restore engine power, the engine regained partial power; however, it was inconsistent and insufficient to sustain flight. Realizing the airplane could not reach U36, the pilot moved the mixture to idle cutoff, closed the fuel selector valve, turned off the ignition, and then initiated an emergency landing to an open field. During the landing roll, the main landing gear dug into dirt, and the nosewheel hit the ground hard and then collapsed. Subsequently, the nose dug into dirt, and the airplane nosed over. The pilot reported that he did not apply carburetor heat while troubleshooting the loss of engine power.

According to the Federal Aviation Administration’s carburetor icing probability chart, the temperature and dew point that existed when the engine lost power were conducive to the formation of serious icing at cruise power. Special Airworthiness Information Bulletin CE-09-35, “Carburetor Icing Prevention,” stated, in part, that "Pilots should be aware that carburetor icing doesn't just occur in freezing conditions, it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity."

Examination of the airplane revealed that the vertical stabilizer, rudder, and fuselage had sustained substantial damage. The right and left wings remained attached to the fuselage. Both the left-and-right wing fuel caps were secured to the wings. No fuel was found in the left-wing fuel tank, and about 1 gallon of fuel was drained from the right-wing fuel tank. The fuel vents were free of debris. The gascolator was intact and contained some fuel, which was free of debris. The screen was also free of debris. The fuel selector valve handle was in the "off" position, the primer was in the "in and locked" position, and the propeller lever was in the “full-forward” position. The throttle lever was about 3 inches from full forward. The mixture lever was set to full rich. The carburetor heat was in the “off” position.

The engine was separated from the airframe and its mounts. The oil sump exhibited impact damage. The exhaust exhibited impact damage. A portion of the induction system (aft elbows) was separated. The engine crankshaft was able to be rotated. Rotational continuity was established throughout the engine and valve train. Thumb compression and suction were obtained on all six cylinders.

The magnetos remained attached to the engine. When the crankshaft was rotated by hand, both the left and right magnetos produced spark on each ignition lead in proper firing order. The upper spark plugs had a light gray appearance in the electrode area, appeared to be oil soaked, and exhibited normal wear for their service life.

The carburetor was separated from the induction system. The throttle and mixture arms remained attached and actuated freely from stop to stop. When the throttle arm was actuated, the accelerator pump actuated; however, no fuel was expelled. No fuel was observed in the float bowl. The plastic floats and the needle valve were intact. The carburetor fuel screen was free of debris. The venturi was intact.