When is a prop change a "major mod"?

When is a prop change a "major mod"?

If one changes from one brand prop to another of the same basic type and of the same weight, is it a major mod and thus requiring a change back to "Phase I"??

Surely if you go from fixed pitch wood to constant speed metal and add 20-30 pounds out on the nose, this is major.

But if they were both wood and they weighed the same and were mounted the same, how is it viewed??

James
... curious

This is one that will vary with your ops limitations. If yours are the newer (last few years) then going from one fixed pitch prop to another is OK. You just need to put the plane back into phase 1, fly it for five hours, make a logbook entry that all is OK and move on. Going from FP to CS would require more paperwork, the details of which I'm not to certain of. Mel???