Idk what function to use... maybe u can use the onPlayerDamage and check if the attacker is vehicle and if vehicle model is an helicopeter and then cancelEvent(), but if u use the hunter whit missiles u doesn't damage, idk try
if the file to call LUA Funcs is a dll u can try it: MTA San Andreas\server\mods\deathmatch\lua5.1.dll
and if doen't work there is the "module SDK" in MTA San Andreas\development idk what does it do, but take a look @ this
Maybe i'll close my own server... and i am looking for a place as scripter (just race servers!)
If you are you are interessed add me in skype: skiper964