Thanks to the FAA’s willingness to consider industry input early in the airworthiness directive process, AOPA was able to gather data and work with the agency to prevent an AD that would have affected more than half of the aviation fleet.
The issue centers around float-type carburetors on 127,000 aircraft. During the past two decades, float-type carburetors have been a contributing or causal factor in accidents. Because of that, the FAA issued an airworthiness concern sheet earlier this year addressing that issue and officially starting the AD process.
Through data collected by the AOPA Air Safety Foundation, AOPA was able to show that while float-type carburetors were a contributing or causal factor, the problem with the carburetors that caused those accidents were not the same. For example, in some cases the wrong float-type carburetor was installed on the engine; in others, it was a gasket problem.
Because of AOPA’s research, the FAA has instead issued a special airworthiness information bulletin (SAIB) that alerts pilots of the potential hazards associated with float-type carburetors. The FAA recommends that pilots examine the engine area for fuel leaks during preflight; watch out for carburetor flooding during engine start; monitor fuel consumption; and be vigilant of difficulty shutting down the engine when the mixture is pulled to idle cut off.
Owners, operators, and mechanics should inspect the carburetor for signs of fuel leakage; inspect for fuel stains; comply with engine and carburetor recommendations from the manufacturer; and overhaul the carburetor every time the engine is overhauled. The overhaul interval could coincide with the engine overhaul, or occur every 12 years or 2,400 hours, the SAIB recommends.
“The FAA really considered our concerns, analyzed our data, and came out with the best action for pilots and aircraft owners,” said Leisha Bell, AOPA director of aircraft and environmental issues. “The recommendations in the SAIB are reasonable given the history of our piston fleet.”