AA will collect the overweight fee for bags over 50 lbs. No way around this and it applies to all AA flights world-wide (once they get the Japanese govt to agree to the change, until then NRT gets 70 lb bags for free). Luckily the fee is nominal (USD 25) and I can't remember the last time I actually had a bag that weighed over 50 lbs. It is an interesting burp in the OW system but hardly the first. AA will let you have a carry-on of up to 40 lbs for free, though (whereas most other airlines are a bit saner and won't allow that much weight above your head).