Take the example of an engine fire or damage scenario where the first bottle was fired. Now it is the middle of winter (of course) and you pick up ice which cannot be shed because you cannot use wing anti-ice from one bleed source because the cross bleed must be kept shut. Somewhere in the QRH PER section there is the example of SHUTDOWN with ENG FIRE pushbutton pushed and Ice Accretion. It has a delta ref of 10 so there will be a penalty to LDR.
I am sure my learned colleagues will come up with better examples but I like to keep it simple.