I visited the workshops there as part of a guided tour which was organised by the LVTA of which I'm a member. We had a rally at this railway as part of a themed weekend. The work involved in looking after steam locos is very expensive. The boilers need re-certifying every year, and every 3 years the loco is fully dismantled for a "heavy general" overhaul. That means right down to the frame. That means safety is more likely to result than in the world of aviation, where as recent events unfold with the 737 Max the regulators simply trust the manufacturers to get it right. But they didn't........................ fiscal intervention ensured that timeliness took precedent over careful scrutiny of new software, by pilots and engineers.
I'm quite surprised a preserved railway would have got hold of one, but I can't think of any other vehicle that has that sort of air-sprung suspension, so they must have, despite Vivarail essentially snapping up almost all of the cars.