This is a Ultimate Pack for Half-Life, Opposing Force, Blue Shift and several mods replacing a wide selection of models, skins, background, sprites, sounds.
Apache model: Unknown, Richard
Barney model: Gearbox, A.I, Werewolf, Liquidator, Niklu, Vox-Bloodstone, Richard
Scientist: A.I, Water-Phoenix, Tony Freeman, Richard
Yeah. I converted that Apache from GTA:SA a long time ago. I completely forgot about it.