The airport owned by Wayne county. TSA/FAA rules apply in the sterile area. I don't have those at the moment.
http://www.metroairport.com/pdf/WCAA_Airport_Ordinance.pdf
WAYNE COUNTY AIRPORT AUTHORITY
AIRPORT ORDINANCE
11.8 No Concealed Weapon or Explosive. Except as provided in Section 11.8 (e), a person shall not:
a. Carry on the Airport a deadly or dangerous weapon, concealed or otherwise, on or about his or her person or in property accessible to them prior to entering a Sterile Area or Secured Area unless the weapon:
1. if a firearm, is unloaded or, if not a firearm, is de-activated to the greatest possible extent; and
2. is packaged for shipment in a locked container or is otherwise secured; or
3. is in the possession of a Person licensed by the State to carry a concealed weapon.
b. Carry on the Airport any explosive or incendiary, concealed or unconcealed, on or about his or her person or in property accessible to him or her; or
c. Carry on the Airport any explosive, incendiary, or deadly or dangerous weapon on or about his or her person or in property accessible to him or her:
1. when performance has begun of the inspection of the individual’s person or his or her accessible property before entering the Sterile Area; or
2. when entering into or while in any Sterile Area or Secured Area of the Airport.
d. For the purpose of this Subsection 11.8, a weapon shall include, but not be limited to, a firearm, a pellet pistol or rifle, a knife, cutting instrument, blackjack, bow and arrow, sling shot, metal knuckles or martial arts weapons.
e. Section 11.8(a) shall not apply to those Persons authorized to carry a weapon on an Aircraft or to a law enforcement officer while on official duty. Section 11.8(a), (b) and (c) shall not apply to Persons who have received the express written permission of the CEO to carry weapons, explosives or incendiary devices on the Airport.