We have what's called a Minimum Equipment List or MEL which explains what equipment can be inoperative, it also explains how this affects you operationally, and any restrictions you may face. I think if you search your IPad, you'll find one too. Not sure what you go by Air Hoss, but if your afraid to fly with an inoperative APU, your in the wrong business, or you need to grow a pair.... I even (gasp) used to fly a turbine plane without an APU installed, and I survived.