Originally posted by Tiny:
Stop drilling cracks is common when repairing aircraft. It probably isn't necessary if you're going to weld the crack anyway.
This is true. Small cracks are often stop drilled and nothing else, other types of patching such as doublers and scab patches are added to reinforce the area. It' really isn't necessary if you're going to weld the crack because the weld does more than the stop drill to stop the crack from extending.
Another interesting thing to ponder... Rolled steel is very malleable and only cracks when work hardened. Work hardening changes the grain structure so I guess depending on how much of the surrounding area has been work hardened I could see how a crack could form next to weld.
Not sure what kind of heat treatment is needed to correct the grain structure in work hardened steel, but I'd be strongly tempted to preheat the surrounding area prior to welding.
