huey · noun1
Derived from Huey, applied by extension to all helicopters, during the Vietnam War.
Huey · proper noun2
From the pronunciation of Hughie.
Huey · noun3
From the original US Army designation of the Bell 204/205 helicopter, "HU-1", acronymized into "Huey", and extended to cover the Cobra gunship version of the same platform.
Etymology from Wiktionary, CC BY-SA 4.0.