1. 8450. Which aircraft record entry is the best description of the replacement of several damaged heli-coils in a casting? A. Eight 1/4â20 inch standard heli-coils were replaced. The damaged inserts were extracted, the tapped holes gaged, then new inserts installed, and tangs removed. B. Eight 1/4â20 inch standard heli-coils were installed in place of damaged ones. C. Eight 1/4â20 inch standard heli-coil inserts were repaired by replacing the damaged inserts with a lock-type insert, after the tapped holes were checked for corrosion.