While I can appreciate the common practice of flushing RR 250 turboshaft engines operated in a marine environment with distilled water on a regular basis to comply with OEM warranty requirements, I don't see how it really reduces surface corrosion of compressor blades. Even after the compressor blades are washed with distilled water, in a marine environment they will still be exposed to more salt air unless the engine volume is purged and sealed.
A more serious problem presented by introducing water into the internal space of a shut-down turbine engine is migration of water past the seals and into the engine's lube system, where it will cause corrosion of bearings, shafts surfaces, etc. The labyrinth seals used in most turbine engines quit working when the flow of bleed air stops.