It varies from system to system. The HH-60 Pave Hawk, for example, (USAF variant of the UH-60 Black Hawk) is well understood and on a regular maintenance schedule like you talk about. However, the USAF contract didn't require Sikorsky to hand over tech data and, instead of purchasing it, the USAF program office essentially reverse engineered a large portion of it.
Go to the JSTARS, the maintenance is almost entirely done by NG (which also bit them, they fucked up the work on one and caused it to be grounded overseas after the issue caused a fuel tank rupture during midair refueling).
There's also been a rush during Iraq & Afghanistan to push out small-run proprietary systems into the field for specific purposes, which also creates complications. Even if permitted, many of these systems end up being unmaintainable in the field due to the lack of maintenance tech data since it isn't required by the contract and lack of experience with the systems due to their relative novelty.