I have this MD500 Defender almost two years, I don't fly much with because lack of time, in fact the last time was 8 months ago !!the problems appear ONLY when I fix the Missiles in the fuselage
since the first flight I have serious vibes problems, I mounted lot of this models with five blades, and this is only that I have this issues, I tried all the mods to avoid vibes, the mechanics is perfectly anchored to the fuse, the blades balanced 10 times, the main shaft, motor, belt....all verified many times and even changed parts...Always the same vibrations ONLY with the missiles pods.
This is the last video, clearly can see the vibrations on the pods.
The one is the MD500 Defender with TRex 600's mechanics, Lightning Heli Head and Thunder Tiger 600mm Carbon Blades...
Watch at YouTube