FADEC normally means Full Authority Digital Engine Control, and implies that it has the authority to shut the engine down. Not all Digital Engine Controls are FADEC. The only ones I know that are true FADEC are on the Bell 407 and Bell 430 - others are DECs (but I could be wrong).
The FAA insisted that prior to installing anything that is even remotely capable of putting out electronic signals onto a DEC equipped helicopter, that a series of Electro-Magnetic Compatibility tests be carried out. I don't have the full reference in front of me, but check with your airworthiness authority who should be able to point you in the right direction.
The DEC (or FADEC) should be immune to all this sort of thing, but you never know....