ANC19LA032 · Cessna 172 M

The pilot and two passengers were returning from a sightseeing flight. While cruising at an altitude of about 1,200 ft, the engine began to surge between 2,100 and 2,600 rpm. To correct for the surging engine, the pilot switched fuel tanks, enriched the fuel mixture, and applied full throttle, to no avail. Unable to maintain altitude and to avoid undue harm to persons on the ground, he selected an area of hilly, sand-covered terrain for an emergency landing. During the emergency landing, the airplane sustained substantial damage to the wings and fuselage. The pilot stated that, the day before the accident, the left and right fuel gauges indicated about 3/4 full and 1/4 full respectively; however, he said it was possible that he had run out of fuel. The airplane had not undergone an annual inspection in 4 years. Postaccident examination revealed that the main fuel line to the carburetor had separated at the carburetor casing and the strainer cable had stretched, releasing any contents that may have been present in the gascolator during the accident sequence. The carburetor half screws were in and safetied but loose and did not appear to be torqued. Brown deposits were observed on the exterior of the carburetor emanating from the carburetor half seam. Although it is evident that the carburetor had been leaking for an undetermined time, blue streaking would have been more likely if a significant and recent fuel loss had occurred. No fuel was found in the remainder of the fuel system, including the wing tanks, associated lines, and carburetor bowl. Based on the lack of fuel present in the fuel system, it is likely that the pilot miscalculated the amount of fuel onboard before the flight, which resulted in fuel exhaustion and a subsequent loss of engine power.

Verbatim NTSB analysis and probable cause from the NTSB dataset