I think the MAAS is a mistake.
Nothing fits it in the USN glossery of abbrevations.
MAA -- Master-At-Arms
MAAF -- Mediterranean Allied Air Force
MAATC -- Mobile Anti-Aircraft Training Center
MAB -- Marine Air Base
MCAAS -- Marine Corps Auxiliary Air Station
MCAS is listed and there are lots of them... now and back when.
MCAS -- Marine Corps Air Stationhttp://www.history.navy.mil/books/opnav20-p1000/M.htm
As to what 406 means... do some research.
Start here and find out if the various bases/stations have a number attached to them. If not maybe a squadron within the base maybe? http://en.wikipedia.org/wiki/List_of_Un ... tallations
Oh, how about some photos, please?