Piper PA-24-250 N7440P accident near Wasilla, Alaska

Probable cause

A loss of engine power due to the blockage of the carburetor air inlet by a piece of engine baffling. Contributing to the accident was a worn engine baffle, and the pilot/owner's failure to have the engine baffle replaced.

NTSB analysis

The private pilot was on a Title 14, CFR Part 91, local area personal flight when the accident occurred. As he approached his destination airport he applied full carburetor heat, which resulted in a loss of engine power. After completing emergency engine procedures he was unable to restore engine power, and selected a shallow lake as a forced landing site. The airplane sustained substantial damage to the fuselage during the forced landing. The pilot reported that while the airplane was being disassembled after recovery, his mechanic removed the lower engine cowling, and discovered a worn, 4 inch by 2 inch portion of rubberized baffling material lodged inside of the carburetor air box assembly. An NTSB investigator traced the origin of the baffling to a worn, frayed, and torn section of engine cowling baffling adjacent to the carburetor heat fresh air inlet duct. The pilot/owner of the airplane reported that he was aware of the worn, frayed and torn engine baffling, and he planned to have it replaced at the airplane’s next annual inspection. Given the discovery of the baffling material inside the carburetor air box, it is likely that once carburetor heat was applied, airflow pulled the baffling material into the carburetor inlet, restricting airflow to the carburetor with the resultant loss of power.

Text from the NTSB. Open the NTSB docket for ANC09LA042 for the full record.