WPR25LA082

The pilot stated that the airplane was too high on landing approach and he applied full power to initiate a go-around. Shortly thereafter, the engine rpm began to decrease. He verified that the mixture, throttle, and carburetor heat controls were all fully forward and confirmed that the fuel selector was set to both tanks. When he moved the throttle aft and forward, the engine briefly surged, and the rpm increased. As he searched for a suitable forced landing site, the engine then lost rpm again. With limited options, he made a 180° turn in an attempt to return to the runway. The airplane collided with trees and impacted the ground in a nose-down attitude. A postaccident examination revealed no evidence of mechanical malfunction or failure. The reason for the partial loss of power could not be determined.

Examination of the airplane’s documentation indicated that the most recent maintenance performed was an annual/100-hour inspection on January 9, 2025. At the time of inspection, the tachometer reading was recorded as 2,774.6 hours. The tachometer reading at the time of the accident was 2,799.52 hours, indicating that the airplane was operated 24.92 hours since the inspection. The last documented fueling occurred on January 22, 2025, the day before the accident, with the addition of 20.968 gallons. On January 23, 2025, about 1515 Pacific standard time, a Cessna 172K airplane, N79910, was substantially damaged when it was involved in an accident near Columbia, California. The pilot and passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that, on final approach for landing, he noted that the airplane was high and performed a forward slip in an attempt to descend faster. As the airplane approached the runway, it was still too high, and the pilot determined there was not enough available distance to land safely. The pilot initiated a go-around and pushed the throttle fully forward to increase engine power and turned the carburetor heat on. Shortly thereafter, the engine rpm began to decrease. He verified that the mixture, throttle, and carburetor heat controls were all fully forward and confirmed that the fuel selector was set to both tanks. When he moved the throttle aft and forward, the engine briefly surged, and the rpm increased. As he searched for a suitable off-airport landing site, he observed that the surrounding terrain was hilly with trees and brush. The engine then lost rpm again. With limited options, he turned left 180° in an attempt to return to the runway. While transmitting a radio call to report the engine failure, he noticed that the radios had gone blank. The airplane collided with trees and impacted the ground in a nose-down attitude. The pilot had a GoPro camera inside the cockpit that recorded the accident sequence. The recording showed that, about ten seconds after initiating the go-around, the engine began to sputter. Based on comparisons with local landmarks, the airplane traveled about 2.55 miles from the airport before turning back toward runway 35. The final recorded position placed the airplane about 1,592 feet from the accident site. The camera position obstructed most of the instrument panel and throttle quadrant. No gauges or displays were visible. The engine cylinders’ combustion chambers were examined through the upper spark plug holes with a lighted borescope. The combustion chambers remained mechanically undamaged, and there was no evidence of foreign object ingestion or detonation. There was no evidence of valve-to-piston face contact observed. The gas path and combustion signatures observed at the spark plugs, combustion chambers, and exhaust system components displayed coloration that was consistent with normaloperation. There was no oil residue observed in the exhaust system gas path. Investigators achieved manual rotation of the crankshaft by rotating the propeller by hand. Thumb compression was established in all cylinders. Valve train continuity was observed, with approximately equal lift action at each rocker assembly. The accessory gears were undamaged and had a light residue of oil. The muffler assembly was removed from the engine; one header pipe was detached, and internal examination revealed no obstructions to exhaust gas flow. The intake tubes at each cylinder were removed, and the induction plenum was internally inspected, revealing no obstructions. The ignition system was intact, with all spark plug leads secured at their respective spark plugs. Both magnetos were secure at their respective mounting pads. Both magnetos were removed, their drives were intact and undamaged, and both produced spark upon manual rotation. The carburetor remained securely attached to the engine with mixture and throttle controls connected. Carburetor control cable continuity could not be fully verified due to impact damage at the firewall. The carburetor was removed and opened for examination. The fuel bowl was clean, without visible contamination. The composite floats and the float arm were intact and undamaged. The fuel inlet filter at the carburetor was free of visible contamination, the main jet was unobstructed, and the venturi was secure and intact. The accelerator pump plunger gasket appeared somewhat dry yet pliable. The carburetor airbox was removed along with the air filter element; both were free of foreign objects or airflow obstructions. The foam filter element was intact and unobstructed. The propeller remained securely attached to the crankshaft flange, with both blades intact from tip to hub. The propeller blades exhibited minor leading edge nicking. Fuel System The pilot reported that he had 38 gallons of 100LL AvGas onboard the airplane at the time of impact. The fuel selector functioned normally in all positions (Left, Right, Both, and Off). The gascolator was removed and contained about one-quarter pint of clean, blue-colored fuel; the internal gascolator screen was clean, though minor corrosion was noted in the bottom of the bowl. The gascolator drain remained attached to its bracket, which was broken free from the gascolator itself. Continuity was confirmed by blowing air backward from the gascolator through the fuel selector valve with no obstructions noted. Fuel lines from the fuel selector were individually disconnected and continuity verified with no obstructions. Disassembly of the fuel selector revealed all poppet balls in place and moderate wear on the cam, though it still functioned properly with distinct detents. The linkage between the fuel selector handle and valve was bent, consistent with impact damage; the surrounding floorboard was buckled. The fuel line connecting the gascolator to the fuel selector was disconnected forexamination, revealing no internal obstruction or significant deterioration, although there was a slight imperfection of metal observed inside the ferrule clamp. Approximately two tablespoons of fuel, containing sediment, were recovered from this fuel line. A jar of fuel recovered from the left wing during aircraft recovery appeared cloudy yellow with sediment observed at the bottom. The jar had been sitting outside and exposed to sun. The amount of fluid was not enough to be tested. The examination revealed no evidence of mechanical malfunction or failure.