TM - I do not have enough personal experience to answer your Q but will find out. My calculations are based on:
155 KIAS, 2000 kgs full, 30 min reserve, 490-510 kgs/hour burn at a cruising altitude. She is a very fast helicopter.
Is your requirement straight out and straight back?
DB
I think your TAS & FF figures are a bit optimistic. Also, you make a statement regarding the new MTOM being 7800kgs. Is it not the case that this is a projected MTOM increase estimated to be certified towards the end of 2016? Your post gives the impression that 7800kgs is the current MTOM.
I suspect you will be nearer 145kts and 540kg/hr at that weight.