Enable or disable mesh renderer of sub-parts of an imported FBX

I have objects (imported fbx), where I need to show them on a certain action or make them disappear … that’s simple with gameObject.renderer.enabled = true; or false,
but some imported object are composed of many part , where the object as a whole does not have a mesh renderer, but the sub parts have.
So what to do in order to make this object disappear.
1- I have to access all the sub-parts of the objects.
Any hints how to this?
2- Or I have to have the object as a one peace object.(I tried grouping in max, but no change)

maybe any other solution!
any hints are appreciated.

for(var r : Renderer in GetComponentsInChildren.())
r.enabled = false;

This gets all of the renderers on and beneath a particular object. That should do it for you…