"Helopat - it's not a case of 'some folks say the 2.5 minute range isn't cumulative' - it is what Rolls Royce say and since they make the engines, they should know"
Well, it's not what Turbomecca, GE and P&W say! Typically they allow 10 minutes of cumulative time at Max Contingency power, between TBO periods. How else could you do topping checks?