Right now I cannot find it in FAR33, but it's been a design requirement on every engine (repeat: Engine) I can recall. It may be a US military requirement carried over as good practice for civil engines.
Don't confuse this with the structural fuse usually seen in engine pylons, which has resulted in some grief on 747's. It is intended to protect the wing spar - maybe not too bad an idea.
Well it's not in any of the FAR/JARs and certainly in no military engine spec based on these regulations and I certainly don't recall it in any military spec that I worked with.
And no I won't confuse it with any requirements under 25.361 & 25.362.