Have you tried your "local" Hughes... sorry Boeing (*)distributor, and any local airfields or helicopter operators? If you cannot get any help from the manufacturer, you will often find other people more than willing to help.
Another possible source would be model aircraft magazines - they have cross-sections, plans and detail photos of all sorts of aircraft. Of course, since few aircraft modellers build modern helis the chances of finding an article on the MD500E is quite low, but you never know...
(*) I think it's currently Boing who "own" the design rights for the 500 series - including the 'E model - even though all the real work was done by McDonnel Douglas Helis before Boing took them over...