Originally Posted by
wiggy
Some of our guys were (and probably still are ) certified to do it on the 747/744 but it involved the handling pilot (usually management ) having done the appropriate sim work up and some slightly cunning procedures that had no doubt been certified by Boeing by virtue of flight testing. There was always had an inert engine, or at least it's core, on the appropriate pylon.
I would expect that they would want to redo the structural analysis of the aircraft with respect to induced oscillations and resonant frequencies if such a large weight with so much leverage was absent.