Thanks for the replies, and sorry for not being detailed enough, initially the question was more of a general nature...ie is stop drilling accepted on hot parts? does the material have anything to do etc. The missing info being : helicopter, turboshaft engine, titanium exhaust with cracks always beginning at the aft side. Im basically trying to filter fact from fiction from a discussion regarding the topic that was held infront of me...
Webby, there is no mention of repair in the manual, and replacement is the given corrective action for cracks beyond a few cm...
Tom I hope above info helps...