'g' is not the best way of determining a hard landing. The limits actually depend on weight, vertical descent rate, and vertical accelleration.
http://essi.easa.europa.eu/ecast/wp-...d-landings.pdf
A hard landing requiring a check is often considered to be over 450 ft/min, but that does not mean much if you are well under MLW. Normal certification limit is 600 ft/ min at MLW, without airframe deformation (equating to 2.5g, I think ??).
But since most pilots cannot tell a 2g from a 3g landing, it is difficult to know when to report. And even the aircraft g-meters do not tell the truth. When Boeing fitted more accurate additional g-meters they showed much less g than the max g. (I think these g readings are in addition to normal 1 g.)
http://www.boeing.com/commercial/aer...onal_fig1.html
The rule of thumb used to be that if the rubber jungle did not come down, she was good to fly.... ;-)