Can't find in in AOM, and if I bought navigraph data from say 6 months ago will it work in the 41?

You can install any PMDG compatible navigraph AIRAC into the system. The one install works for all PMDG aircraft you have installed in the sim... one install for FS9, and another install for FSX. The Navigraph installer asks if the data is to be installed for FS9 or FSX, you need to select the sim prior to installation.There is no indication of the airac in use, but the current data has always worked for me every time I update to a current cycle...I do believe you cannot purchase an older cycle from Navigraph. They only offer the current cycle. If you have purchased an older cycle and you need to reinstall, then the cycle supplied with the aircraft initially will be the valid one, and you may install your purchased cycle over it.Andrew

Andrew is correct, just to add a note that there is not a screen in the JS41 that provides cycle data (that I recall). However, it uses the same pmdg/navdata and /sidstar files as other FSX pmdg aircraft. You can open any of these files and see the cycle information (they are all text files).