We
were minutes away from an engine tear-down, when we tried one more time
to extract the broken tension bolt. The bore scope allowed us to see
exactly where the pilot hole was drilled into the broken piece; the
left-hand drill bits would not grab on and extract the part but did
help in enlarging the hole and perhaps loosening the threads a little.
Ultimately I was able to start an easy-out with light tapping and it
grabbed on – the result is in the attached photo. The easy-out is
welded to the end of the original broken bolt and you can see that a
spiral of RTV was applied to the length of the bolt between the threads
and the bolt head.
Jeff