I wish manual A/B checks would come back to the Maintenance screen. Besides being more steps, having to schedule a check to do a manual B-check has the added result of hiring a crew for that plane if you're set to automatic. If it's your spare plane and it just needs a B-check before you move the schedule, you either have to switch your staff settings to manual first or lose a day of flying when you do the B-check as part of the schedule transfer.
I never understood why it had to be removed in the first place. It was already there in the old UI, why get rid of it?