Gromit......I believe you're mistaken. According to the FAA's travelers website, they advise passengers to check with the airline as to the size and number of carryons allowed. Here is a snipet that I'll provide the link for later.........."Check with your airline before packing to determine it's carry-on guidelines regarding the number of items you may carry and the maximum size of those items."
FAA's travel website
Also, the TSA is not the enforcer, the FAA is. TSA is part of Homeland Security not the FAA or even DOT.
This wasn't part of what I did so this will serve as my disclaimer for any wrong statements. Haha.....I'm covered.