Here is the inside scoop. It is believed that a partial ring failure caught a port and destroyed the piston. The piston fragments then punched a hole in the cylinder head.
The right side head was a new one we had made during the restoration. SP made a replacement head on that side out of plate steel. It was understandably to weak, in fact it was deformed.
A new head will be made as well as a new piston. The rings on the left cylinder will be replaced to prevent this from happening on that side. I was told the cylinder bore is fine and not scored. 18 WILL be repaired in Durango.
This is simply a mechanical failure, and a rare one at that. 18 is in good hands with 4 key members of the Carson & Colorado rwy employed at the D&S. We are actually glad it happened in Durango, as it will be easier to repair there vs in California.
Jeff Taylor
CRRM curator of equipment and rolling stock.