ORIGINAL: badazzbusa
Usually everything on a heli is metric. You will need a variety of lengths, usually 2mm, 3mm, 4mm size. The thread cut is generally the standard cut for that size bolt.
Check out this kit at RTL, it is a really good deal and they sell individual packs so you can restock as you go.
http://rtlfasteners.com/RC/908.html
I bought one of these a year ago and use it constantly. It's kept me in the air without hunting all over town for one little metric bolt or nut. Well worth having!