Cessna 180 N3246D accident near Omaha, Nebraska

Probable cause

A loss of engine power due to a stuck check valve in the carburetor acceleration pump, resulting in an improper fuel mixture when the pilot attempted to add power.

NTSB analysis

During the landing approach and 1/2-mile from the runway, the engine lost power. During the ensuing forced landing, the airplane impacted a tree and terrain. During postaccident functional testing of the engine, it lost power when the throttle was moved quickly from a low power setting to a high power setting, and became more pronounced as the engine got warmer. The carburetor was removed from the engine and a visual inspection was conducted. A roughness was felt in the accelerator pump while manually moving the control at the carburetor, and very little fuel flow came from the accelerator pump. The carburetor was disassembled and all check valves, ports and vents, the venturi, nozzle bleed holes, carburetor bowl vent channels, and float assembly were cleaned. After reassembly, a much higher fuel output was achieved. The carburetor and accelerator pump were reinstalled on the engine, and all functional checks were normal.

Text from the NTSB. Open the NTSB docket for CEN11LA089 for the full record.