Redhawk, a base will not routinely have a mix of airframes. Either 2 x S92 or 2 x AW189(eventually). If a type is grounded, then the other type will be loaned from a nearby base thereby maintaining the coverage, providing you don't have any aircraft in deep maintenance at that time. Each base has historically been manned by 4 x aircrew and 2 x engineers on a 24 hour duty period. You don't have a fixed crew system, personnel are completely interchangeable. Also you have a (generally) day working Chief Engineer, and when there are times requiring more intensive maintenance you bring your off duty engineers in on o/t. Roughly speaking you have 10 Pilots (6-7 Captains), 10 rear crew, and 10 engineers. Also a part time admin person and a labourer to maintain the hangar etc. Crews will on average work between 6 - 8 24hr shifts per month