Are you saying that 6 - 8 engineers can keep a fleet of two (civvie) helicopters airworthy 24/7??
If memory serves me right....a one aircraft, two pilot, one crew member, two Engineers, one Rampy and a part-time admin type did the job of three aircraft and 31 Military Personnel.
Yes....Civvies can do the job.
It takes a good support base that can respond quickly if the Aircraft goes AOG to make it happen. Scheduled maintenance with the use of a spare taken from the rest of the fleet works fine.