2 Cases
I've spoken to two pilots, both 407's.
The problem, the Fadec.
They both on two seperate accounts came to the conclusion that it was cell phone interferrence as they both had there phone up front and promptly switched them off.
In other cases, knowing factual accounts, the governor in the R44 playing up, the one near radio masts and the other with equipment on board running a windows based program. Now how many of these cell phones are now using windows based products aswell as getting more powerfull.