What i have to do to disable damage from a scrapheli explosion or  destroying falling on a structure ??

i tried :
"fire cannot hurt anything"
"minicopter cannot hurt anything"

"name": "fire"
"members": "FireBall, oilfireballsmall, oilfireball2"

"name": "minicopter"
"members": "minicopter, minicopter.entity, scraptransporthelicopter, servergibs_scraptransport"

Some one know how to make building immune to those heli debris ??