I'm not a fan of the AW139 training switch. It bites instructors if they relax and it's not representative training. Because it caps available power at 70/70 it droops Nr at a simulated 140 OEI where as for real with no alt holds you have 160. This is roughly the equivalent of simulating an aircraft 500 kg heavier than the one you are in. But by far it's worst feature is the safety function that kicks out the switch if Nr is drooped to 87%. In itself that is a good thing but the way it restores power is not. The training switch kicks out and the EECs instantly respond by trying to restore Nr. They accelerate the engines against no resistance until they smash into the falling Nr. It is a very violent application of power and it's no surprise that this can result in transient Tq spikes