Heli-coils are stainless steel and the OD is now larger, more strength, and now the threads will not wear. I would not Heli-coil good aluminum threads, but I have no problem installing and using them. When I worked in Quality, Government reps had to approve any repairs on certain contracts. Heli-coils were considered rework and no approval was needed. Studs are the best thing to use in aluminum since the steel or stainless steel full length threads of the studs are in the aluminum. The studs would then take any wear or cross threading.
