Fair point, clearly, when you have a fleet of trains which is expected to fail relatively frequently. Looking at a few photos seems to suggest that, as I remembered, the Chiltern units have no opening hoppers at all, not even for “emergencies”. I guess Chiltern must just look after their trains that much better than GWR do (and of course were prepared to spend extra money at refurbishment time to replace the windows) that the eventuality of the air cooling failing simply never happens (for some definition of never). Comparing the overall experience of travelling in Chiltern 165s with GWR ones (and indeed 166s), the former certainly feel enormously better maintained / less “worn out”. It'd be genuinely interesting to know what the relative failure rates (for various types of failure) of the two fleets are, but I guess that's commercially sensitive (despite being of great interest to the travelling public that pays for the service) so it's unlikely to see the light of day. But we're getting off topic (happy to open a new topic or move across to one of course, but we're away from GWR livery now!).
