Todjaeger
Potstirrer
I agree that without more information, knowing if the comparison is an "apples to apples" comparison is difficult. It might be helpful if someone could dig up a copy of what the Australian S-70A-9 Black Hawk maintenance-hours per flight-hour ratio was, especially if it was compiled by the ANAO.
I did do a bit of additional digging into some of the US Black Hawk maintenance schedules and what I came across suggested that there three levels of maintenance, Unit level, Intermediate level, and Depot level, with maintenance being done on a schedule based upon both time, and certain maintenance being down after the accumulation of so many flight-hours. The first benchmark was after every 40 flight hours, a series of checks, tests and replacements which on average took 15-20 maintenance hours to complete.
Incidentally I dug up a GAO report from 1983 on the UH-60A Black Hawk which discussed how it was performing with respect to availability rates, maintenance staff-hours per flight-hour and other related matters. One of the early requirements for the Black Hawk, which was being met back in 1983, was no more than 3.8 maintenance staff-hours per flight-hour, and that was with the three levels of maintenance work. I also found it interesting that due to parts shortages and more maintenance required due to higher than planned flight-hours, the mission capable rate fell below the desired target. The part I found specifically interesting was that the lowest rate, which did not meet the US target at the time, was 67.8% out of a target of 80%. That 'failing' rate was 2.8% higher than the serviceability target that Australia has (or had) for the MRH-90 Taipan which was 65%, and when the ANAO report came out, indicated that from 2013-2014 the actual rate was only 48%.
Again, we still do not know if the maintenance-hours per flight-hour numbers are an 'apples to apples' comparison, but there are two reports which have different model Black Hawk helicopters (UH-60A and UH-60M) with maintenance-hours per flight-hour in the mid-single digits, and these reports were published by different US government agencies (GAO and DOD) 30 years apart, with neither report indicating that the maintenance to flight time ratio was only applicable to one level of maintenance.
As a side note, I came across an Australian Army Journal from 1970 that listed the CH-47 Chinook as requiring 19 maintenance-hours per flight-hour after three years of service and this was at a time when the engines had to be changed every 300 hours, though at the time there was a goal to increase the hours to 600 or even 1,200 hours before having to change engines.
