How can the effects of hot corrosion and salt deposits from sea water spray in gas turbine engines be negated/prevented? In aircraft operating in a maritime environment, corrosive effects from salt water are common. Are there any specific coatings used in engines for such aircraft? If so, which are they? How frequently should they be washed?
I've looked for information on this but can't find any specific answer.
Not aware of any anti-corrosion coatings used in engines.  The best mitigation is to shoot fresh water into the inlet with it running at the end of the day.  Seaplanes operating off salt water will generally get a fresh water hose down at the end of the flying day whenever practical.