Hi Hans,
Whilst Merchants need an annual maintenance to get a certificate of spaceworthiness, license to trade and license to carry passengers that doesn't really apply to military craft, if anything goes wrong stick a pre-purchased spare part in. (Although Mercenaries probably need it for their Merc licencse).
Trillion Credit Squadron requires 10% maintenance, but unlike repairs and refits
doesn't require an A or B startport. That said nothing to stop a regular refit every 8-10 years (In my example I'd use Tarsus TLA class B spaceport as it's on a J1 route from Ochecate.
Regards
David