I am more interested in the fact that Mark Hobbs, IPTL at the Herc Inquest stated that fitness for purpose was not an an area of his concern. He was only interested in airworthiness and wiped his hands of any aircraft needing foam.
A rough note of Hobbs at the Inquest, (not word for word).
"The difference between airworthiness and fitness for purpose is that I make sure its airworthy, that no intrinsic fault or failure could bring it down. My job to ensure, for example, it gets to USA safely. In fitness for purpose, you have to consider uses. A car without ABS is not necessarily unsafe, but it may be unsafe if you want to go much faster. It becomes not fit for the purpose you want to use it for."
"Fitness for purpose resides with operators, not us."
Edited to add, not lucky at all, the MoD and RAF were culpably negligent..