Inop TCAS is normally a 10 days MEL item. Most countries in Europe have no problem operating for 10 days with u/s TCAS except Germany which have a quite stupid rule of max 3 days (altough even their ATC guys are not aware of this apparently). They have no way to find it out either unless your company run at least a half-decent Operations Control who files your flight plans marking TCAS being inop (non-RVSM).