LZ
One aspect of this checklist would be directed at parts or assemblies that could be installed backwards. In the case of the Air Transat engine this would include the fuel line and the hydraulic line both of which could be installed backwards
I don't think anybody has said that anything was installed
backwards. If your post was making this assumption, than a very elequant post it is, but nothing to do with this incident.
The problem was a properly documented RR mod package, which was only half incorporated (some pre-Mod bits and some post-Mod).
The problem was not really RR's. It was with the procedures (or lack of) when the engine change occurred. It was not helped by some of the contractual arrangements and expectations in the "pool" engine arrangments, and who was responsible for incorporating mods etc.
NoD