"Five engine 747 configurations do occasionally happen, though."
I'm sure you're aware, that extra-engine isn't plumbed in and is the rare example of Quantus strapping a spare engine to take to another aircraft. It's basically external cargo. :-)
Strictly speaking though, all 747's are 5-engined. If you include the APU in the tail. :-D
Biting the hand that feeds IT
