Thank you. I did some quick tests with the X-Plane Equipment Failures.
Engine fire, magnetos and oil pump work, on the other hand, generators, engine failures, OAT and fuel quantity sensors do not work.This is of course just a small subset of all available failures.
This looks like it really just depends on how PMDG made use of X-Plane's default features.
To me this is a bit disappointing because such a sophisticated airplane (even if its not a study model) does not even make use of default X-Plane features which would have enhanced the model quite a bit. So from a failure modelling point of view even X-Plane's default aircraft provide more depth.
regards
Nik Schild