Rotor Pilot,
no we don't have sandfilters. We hardly ever operate in sandy/dusty areas, besides the air-intake of the turbine on the EC120 is well hidden. The air has to go around a lot of sharp corners before getting to the intake.
Also if compressor deterioration was the problem it wouldn't show up intermediately - sometimes on sometimes off!
Thanks it was just a long shot.
I flew for a couple of years in areas where the dust and sand would cut the TBO's of the engines in HALF by transforming the compressor blades into grotesquely deformed razor blades. We were getting 500 / 600 hrs from each engine, tops.
So we had to install sand filters. After this we started having some variations in temps caused by the filters (if they were dry, or humid or wet or clogged they would affect the readings accordingly to their condition at any given time).
Can’t figure out anything else. Intermittent malfunctions are terrible even in computers let alone flying machines