You’ve heard of engine out approaches, but what about the dreaded extra engine approach? Ok, so the extra engine isn’t actually providing thrust, but it does create significant drag.
With such a disbursed network spread over really long distances, Qantas occasionally faces unique maintenance challenges when one of their jets breaks down. Recently, one of their 747-400s needed an engine replacement at Johannesburg, South Africa. Qantas’s options to ship a new engine to South Africa from Australia are pretty limited. A Rolls Royce 747 engine is too expensive and complicated to just buy on a whim. It’s also too big to fit in the cargo compartment of an airliner. The options are either to charter an outsized cargo aircraft or wait weeks for one to be shipped via ocean freight. Instead, Qantas leveraged yet another unique capability of the 747. Flight QF63 flew from Sydney to Johannesburg with an extra engine secured underneath the left wing of a sister 747. While this is unusual, it’s not unprecedented. The 747 aircraft actually have an attachment point for a spare engine. Flying a 10,000 lb engine on the wing of a streamlined aircraft isn’t without penalty. Qantas said that they had to make an extra fuel stop in Perth before continuing their journey and delivering the unique stowaway.
Qantas put together a great video about the journey of the 5th engine. You can watch it below:
BONUS: As an added bonus, we were able to find a more technical video explaining exactly how an engine is prepared for ferry flight.