There have been incidents of the accidental use of the wrong fuel—particularly turbine fuel. Turbocharged piston engines with the term "Turbocharged" painted on the engine nacelle have been interpreted by refueling crews to require turbine fuel. We must remind the pilot-in-command again, as we have over the years, he or she must be responsible for the proper fuel in the aircraft tanks at refueling.
Turbine fuel, or a mixture of turbine and aviation gasoline, has proven to be a particularly ruinous fuel for piston engines. As a result, if the engine has been operated with this unspecified fuel, qualified maintenance personnel must make a detailed inspection of the engine with particular attention to the combustion chambers. If detonation has been severe enough, further damage will occur to crank pins and main bearings, counterweights and valve train components. In view of possible damage, disassembly and inspection of the engine parts is the only safe recommendation that can be made after the engine has been operated with improper fuels. If it has been determined that the engine has been run on unspecified fuel, do not continue to operate it unless it has been inspected and certified to be airworthy by competent maintenance personnel.
Textron Lycoming Service Bulletin No. 398 is the latest reference concerning Lycoming engines which have been operated with unspecified fuel.