shak'n said:
Independant painting of blades results in span moment arm migration which in turn will ultimately produce "rogue" blades and prohibit - or at very least make extremely difficult, the interchangeability of blades within a fleet of same type of helicopters.
While this can and does affect the capability to balance the rotor after the painting process, the main reason 412 blades don't fly well after painting is that the paint finisher spends a nice long time on the blades with a d/a sander smoothing any defects out and feathering any abrupt edges in the paint and ends up reducing the thickness of the blade's trailing edge. Changes of the trailing edge significately changes the blade's flying characteristics. Improper paint prep has caused far more damage to the 412 fleet than applying paint. A paint only problem will manifest itself with the inability to hang enough weight on the m/r head to get the blade balanced. It is worth the cost to send the blade to a properly rated repair facililty so that they can finish it correctly. Over the long term it will cost you less.
If you have to paint your own blades, when prepping the blades be extra careful to scuff the blade just enough for paint adhesion and don't spend a lot of time trying to feather paint chips out. Hand sand only...
Chuck