If you are getting an error when you load the DreamFoil Bell 407 in X-Plane 11.20 (and chances are you probably are), don’t worry. DreamFoil already issued a fix.
The problem has to do with a small configuration file for VR.
Fred, of DreamFoil, posted a replacement file at the .org forums. Replace the one you have on your Bell 407 folder and see the problem go away.