N78720Cessna 182P · 1973

On June 13, 2025, about 1030 Pacific daylight time, a Cessna 182P, N78720, was substantially damaged when it was involved in an accident near Hyampom, California. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that he arrived over the destination, Hyampom Airport (H47), at a cruise altitude of about 8,500 ft msl after delaying descent due to a temporary flight restriction (TFR). Once clear of the TFR, the pilot reduced the airplane’s engine power significantly, reduced airspeed, applied 10° of flaps, and initiated a 7,200-ft descent to land. He reported that, during the descent, he conducted the prelanding checklist, verified the fuel selector lever was on both, advanced the propeller to full forward, and incrementally advanced the fuel mixture to full forward. The entire descent was conducted at a low power setting with the cowl flaps closed to prevent shock cooling the engine. While on the base leg of the airport traffic pattern, he advanced the throttle, with no response. He then applied full throttle, making sure the mixture and propeller levers were full forward. However, he did not apply the engine’s carburetor heat. Unable to maintain altitude, the pilot made a forced landing to a gravel sand bar about 900 ft from the runway threshold. The pilot stated that he landed hard and that the nosewheel and strut separated after impacting large rocks, resulting in substantial damage to the forward fuselage. The airplane came to rest upright about 150 ft from initial touchdown.

A postaccident examination of the airplane and engine did not reveal any preimpact

mechanical anomalies. The fuel system was traced from each wing tank to the carburetor through the fuel selector, which rotated normally and was unobstructed. The fuel lines that had not been damaged by impact or removed to transport the airplane were secure. Recovery personnel reported that about 60 gallons of fuel were recovered from the airplane’s fuel tanks.

Mechanical continuity of the engine was established throughout the rotating group, valvetrain, and accessory section as the crankshaft was manually rotated at the propeller by hand. Thumb compression was achieved at all six cylinders and the valves displayed normal lift when the crankshaft was rotated. Examination of the cylinders’ combustion chamber interior components using a lighted borescope revealed normal piston face and valve signatures, and no indications of catastrophic engine failure.

A High Resolution Rapid Refresh (HRRR) model sounding created by an NTSB meteorologist for the accident time and location indicated that at an elevation of 7,064 ft msl the temperature was about 6.6°C and the dew point was about -5.9°C, with a relative humidity of 40%. The icing probability chart in FAA Special Airworthiness Information Bulletin CE-09-35 indicated that the atmospheric conditions at the time of the accident were "conducive to icing at glide [idle] power." The pilot stated that he did not use carburetor heat during the descent and approach into H47. According to the “Before Landing” checklist in the accident aircraft Pilot’s Operating Handbook, full carburetor heat should be applied before the throttle is closed.