Remember this mod? http://www.gtagarage.com/mods/show.php?id=13289
If you don't feel like waiting for the mod to appear here is the link https://www.mediafire.com/?hm5nldnp8a7h3d1
Well. The creator of that mod said that he tried to mod the catalina helicopter aswell but had no success.
Which means I have been working my butt off non-stop to bring you this mod. Maverick as the helicopter Catalina flies in the last mission.
Installation instructions in the readme supplied inside the zip file.