We had a FADEC switching into manual mode once every 10 hours or so, our Agusta guru Mr. Ramirez detected right away that the problem was that some big wire harness had been made with a certain material that had turned into a gelatin like substance with time, and that caused the FADEC signal to degrade, which in turn made it revert to manual.
How about switching harnesses do see if the failures go to the other side? Bear in mind I am no Eng.
Mr. Ramirez (Our Agusta Guru) is and has been in charge of at least 7 Agusta 109E for the past 7 years, so if something goes wrong with one of those things, he will know what it is. I will as him as soon as I see him, although that might be a while as he is now in NJ supervising the delivery of the first 139 in the country.