Per the information given -
Trailer inspection was conducted on the trailer floor.
Forklift on the upper weight limit, but within wt. capacity of the trailer.
Trailer floor collapsed when picking up the last two pallets. So the front end of the trailer.
I looked up "Forklift falls through trailer" in you tube and found that this event is not new or uncommon.
Any ideas on where to get some more information. Has this ever happened at your plant? Besides the floor, what should the inspection of the trailer include?