[Diablo2006]

look in the aircraft part of the AFPD directory on your hard drive. Look for the plane in this folder that isnt working.
Open the folder (e.g. Katana_ma etc.) and look for Katana_ma.TMD

Right click on it and then in the new list, click on "open as" or "open with"

Select notepad and click OK
Now open the TMD file that will now open in wordpad and at the top their is a number. If it is 1.9.0 then change it to 1.8.0