I think for the MEL you would not have to refrence the FAR's because the MEL a airline uses starts from a Master MEL that the FAA has. So the Airline has to use everything on the Master MEL which would include anything required by the FARs and all the airline can do is add on to it. Hope that helps imperial. Oh and I think they way you are asking if its not on the MEL do you have to down the aircraft. No only if its required on the MEL cause its the minimum equipment required to fly by your ops specs.