Piper PA-18-135 N99640 accident near Wasilla, Alaska

Probable cause

A partial loss of engine power for undetermined reasons.

NTSB analysis

The noncertificated pilot stated that, shortly after takeoff, the engine began to lose power, run roughly, and shake violently. He applied carburetor heat and selected the left fuel tank, then the right fuel tank before selecting both fuel tanks with no change noted. He reduced engine power to control the airplane shaking and conducted an emergency landing. During the emergency landing, the airplane sustained substantial damage to the wings and fuselage.

A postaccident examination revealed that the fuel selector was improperly labeled. However, the examination of the engine, accessories, and the other fuel system components revealed no mechanical malfunctions or anomalies that would have precluded normal operation. As a result, the reason for the partial loss of engine power and the engine’s rough operation could not be determined.

Text from the NTSB. Open the NTSB docket for ANC22LA020 for the full record.