azzmang

Actually Cruising with the anti ice on when not required in not accepted as best practice and it may actually lead to a net Increase in fuel used. This can be demonstrate through some simple examples on a sample route, these figures don't apply to the 1900 specifically but are a nice easy number set to demonstrate fuel usageDistance = 1000NmScenario 1: No Anti-ice on during cruise TAS 250KTFlight time = 1000/250 = 4Hrs at an example fuel flow of 1000KghrTotal Fuel used = 4000KgScenario 2: Anti-ice on during cruiseTAS with A/I on 245Flight time = 1000/245 = 4.081Hrsfuel flow = 995KghrTotal fuel used = 4061kgSo flying with the anti-ice on actually gave a NET increase in Fuel consumption of 61KgThis may not seem like much of an increase but when it comes to flight planning 61kg is and nearly an extra person that can be carried (assuming standard weights) or and extra 61kg of profit making cargo.As for ITT temps im am unsure of 1900C operations but im assuming there was a POH with the product that has recommended cruise schedules including Max range/Max endurance. generally the lower the temperature for cruise the better, it is temperature limiting climb and cruise that become a factor in engine management...I've operated PT6 aircraft in real life and we planned climbs on temp where we limited to 785C ITT on climb and cruise was as per the bookssorry not much help on the 1900C but hope explains the fuel usage thing a little. :( Azz Mang

Anti Ice will reduce fuel flow as bleed anti-ice removes mass flow through the engine core (less air moving through the hot section of the engine) the FCU will sense this reduction in Mass flow rate and meter the fuel so as to bring it back to a stoichiometric ratio. Anti-ice application will often see a 2-3 kt speed reductionBasically:Air Mass Flow down (due bleed demand) = fuel flow down = power downof course this is totally opposite to how turbofan a/c operate where the idle speed will increase with bleed demand and usually result in a FF increase.hope this helps