Let's take this situation... You install an Bell part to your Agusta helicopter. Then, FAA issues an Emergency AD against certain batch of parts, and your part is included in the listing... but how do you know? Since you have an Agusta helicopter you do not need to know about FAA ADs and Bell Service Bulletins, but you must check italian ENAC "Prescrizioni di Aeronavigabilita" ( OK, EASA now, but not 100%) and Agusta Westland Bolletini Tecnici. Since Agusta as TC holder knows nothing about Bell parts installed to Agusta helicopters, they have no means to warn you unless Bell produced part become "Agusta part" by sending them thru their system.
Remember, airworthiness is the responsibility of owner/operator, not your maintenance provider. How do you get around this? Tracking both EASA /Agusta and FAA / Bell documents?
You can sometimes fall in a big trap, if not very careful. Been there, (nearly) done that.
hoistop