Since penalty factor of 180% is huge so the calculation is creating some confusion. Let's take FOB 6000kgs and EFOB 4000kgs. That gives burnoff of 2000kgs. Take a penalty factor of say 15%. When applied to 2000kgs will give 300kgs. Surely that can't be the BO with failure but only additional fuel required. It will be added to normal burnoff of 2000kgs giving the figure off 2300kgs as the trip fuel with failure. So the new EFOB with FPF will be
6000-2300=3700kgs.This should make it clear.