Someone mentioned the Iberia 340 at Quito(?) being 3g
Landing limits are more generally expressed as a rate-of-descent e.g. 10 ~ 15 ft/s max (and at given landing weights)...
The 'G' that something experiences, will
vary across the whole aircraft structure, and parts thereof, depending on it's mass, stiffness, interconnectedness and instantaneous crash dynamics.
For instance, the recent AMS 737 accident, it is quite evident that the forward fuselage experienced
many times the 'g' force of the centre fuselage and wing section.
Ultimately it's the forces that count, which are dependent upon the mass of the part that's accelerated, which (mass) could of course change dramatically during the course of an accident... so any comments on what should and shouldn't break and how, is highly speculative. Granted though, that MD-10 & 11s seem to come apart pretty dramatically in such incidents... it would have been the accelarative forces of the flipping of the right wing, that
seemed to break it outboard of the pylon.