Originally Posted by
Non-PC Plod
Not just the stresses from the low Nr, but also remember the very sudden Nr acceleration you get if the Nr droops too low, and the OEI training mode drops out.
No doubt this puts significant stress on the freewheels and gearbox if it is allowed to get all the way to the 88% cut out (usually with an associated XMSN OVTQ caption unless on the ground). It would seem unfair to apply this as a penalty to every use of training mode given the rarity of it occurring, but you’re probably right. It’s a little like how they penalise the entire duration of a flight at TOW above 4.6t (169), even if it was only >4.6t for the first 5 minutes.