Combat Air Crew Wings were originally awarded to Navy enlisted aircrew in WWII. They were earned by gunners in fixed wing aircraft, such as the Dauntless divebomber. The Aircrew wings were issued after crew status was attained. The stars were added as combat criteria were met in the following: Air to Air, Air to Ground, Air to Sea.
United States Marine Corps Aircrew members received them the same way. In Korea, they modified the criteria for Navy & Marines for helicopter crews.
As early as 1962, they were being issued to Marines in RVN for 21 combat missions, with the three stars representing a minimum of 3 confirmed strikes/firefights ("hot" missions).
A few sets were issued for Beirut, and some for Desert Storm and Somalia, but the criteria has changed drastically.
In the song “Counterattack” there is a verse,
“We've silver wings upon our chest, upon which three gold stars rest, We got our wings the hardest way, not by three jumps in the USA!”
After 21 Missions, it was all gratis! Thus the 21 mission target for all helicopter crew members.
SQUADRON MATES KILLED IN ACTION IN VIETNAM
REUNION INFO - Pensacola Beach - October 2002