Ok, ta!! But I think it is going off thread by saying the units are closed. Downtime in this instance is length of scheduled and unscheduled maintenance, ie aircraft servicability. If the engineers were working on the helis during 'closed' times, then it is fair game to call it downtime.
A question, we do the majority of our flying in the early hours and very little during the day. If we had a 6 hour window, I am sure it would be from 6am to midday. Why do units close at 3.00am? Is there different peak demand hours around the country?