Cessna 172I N8390L accident near Mayer, Arizona

Probable cause

The accumulation of carburetor ice, which resulted in a loss of engine power and a subsequent forced landing.

NTSB analysis

The pilot was conducting a personal cross-country flight with one passenger. During cruise flight, the engine misfired, and engine rpm and performance decreased. The pilot advanced the throttle fully, selected full-rich mixture, and applied carburetor heat, after which the engine rpm initially recovered. The engine then lost power a second time, and the pilot was unable to restore engine power. He subsequently performed a forced landing on uneven desert terrain, where the airplane sustained substantial damage.

The owner recovered the engine and other portions of the wreckage from the accident site. A postaccident examination of the recovered engine components did not identify a mechanical malfunction or failure that accounted for the reported loss of engine power.

The weather conditions at the time of the accident were conducive to the accumulation of carburetor ice at glide and cruise power settings. The engine misfiring and decrease in rpm were also consistent with the indications of carburetor icing. After the pilot advanced the throttle, selected full-rich mixture, and applied carburetor heat, the engine rpm initially recovered. Although the pilot made these control changes simultaneously, the weather conditions conducive to icing, engine misfiring and decrease in rpm, and temporary recovery after the application of carburetor heat were collectively consistent with carburetor icing. Therefore, it is likely that carburetor ice accumulated and resulted in the loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR25LA040 for the full record.