I remember some extinguishants (Methyl Bromide comes to mind) also caused corrosion to some parts of engines and needed treatment after a bottle was discharged (for whatever reason). Mainly, this entailed the removal of the whole engine for strippng.
Again, I seem to remember this being the case on RAF Chinook Mk 1 T55-711 Engines. I don't know if they have changed the extinguishant for the subsequent Marks, or even if this was the case on the BAe 146 ALF engines.