Conservatively, take the grants that are clearly for GA airports only, and
compare that to the number (about $180mm) in combined AVgas and Jet A gas
tax receipts.

There's your fallacy. One should not take "grants that are clearly for
GA airports only" but "grants that are clearly for GA only". There's a
difference.

Or, take "grants that do not benefit the airlines".

Jose
--
There are more ways to skin a cat than there are cats.
for Email, make the obvious change in the address.