Gulfstreamaviator:
I am aware that JAA insist on 50ft being added to non precision MDA, VOR/NDB approaches, world wide.
Yet the FAA do not require this safety margin, which I am told is to allow for the interia in the level out.
What you don't make clear is whether JAA requires this only when MDA is being treated as a DA. In that case, as some here have said, the FAA indeed does require adding 50 feet.
If, however, a NPA with MDA minimums is flown in the manner envisioned in criteria, then no additive is necessary, either under TERPs or PANS OPS, because of the
minimum in minimum descent altitude.