Composition for removing engine deposits from turbine components

A method and cleaning composition for removing engine deposits from turbine components, in particular turbine disks and turbine shafts. This method comprises the following steps: (a) providing a turbine component having a surface with engine deposits thereon, wherein the turbine component comprises a nickel and/or cobalt-containing base metal; and (b) treating the surface of the turbine component with a cleaning composition to convert the engine deposits thereon to a removable smut without substantially etching the base metal of the turbine component. The cleaning composition comprises an aqueous solution that is substantially free of acetic acid and comprising: a nitrate ion source in an amount, by weight of the nitrate ion, of from about 470 to about 710 grams/liter; and a bifluoride ion source in an amount, by weight of the bifluoride ion, of from about 0.5 to about 15 grams/liter. The smut that is formed can be removed from the surface of the turbine component in a manner that does not substantially alter the surface thereof.