Military Man,Due to the fact that only a few A/c still use Pneumatic systems data will become harder to get,Any particular questions in mind ??
Rubbish!
Just about every large transport a/c uses or has pnuematic systems. How do you think they maintain cabin pressure, heat the cabin, start the engines, de-ice the wings/engines and a vast number of other things?
Military man, to be honest there is very little maintenance on these systems these days. Ducts, etc are all 'on condition' items. There will be periodic replacement of filters and traps and the function checks of valves, etc. There will also be leak checks carried out whenever any of these systems is disturbed for maintenance action. That's about it!