As a pilot transitioning to a new airplane, it occurred to me that I don't know enough about what's underneath the cowling. I don't really know what can be deferred during preflight and what is an airworthiness concern on any particular parts. TBH, I have mostly flown well-maintained machines, so my reference point is based on that. Case in point: on a plane that I'm gaining some familiarity with, I noticed a flexible air hose that seemed like it's wearing out. It's the type of hose with a wire coil on the inside for structural strength. But I don't really know the purpose of the hose so I can't make an informed decision about to fly or not. Where can I find a diagram or something that gives some helpful information about what's forward of the firewall and maybe something on the general airframe?