Did you ever imagine what it would be like to witness a plane with five engines? Well, some fortunate passengers and onlookers got their chance when Qantas, Australia’s national carrier, operated a Boeing 747 with an additional engine on its wing around the globe.
The curious sight was recorded by plane watchers and posted on social media, raising eyebrows and wonder. The additional engine was used to replace a failed engine on another Qantas 747 stuck in South Africa. Rather than shipping the spare engine by cargo, Qantas opted to employ a special method that enables the 747 to transport an additional engine on its wing.
The method is referred to as “ferrying” and consists of placing the additional engine on a special pylon on the inner wing’s most forward strut, alongside the number one engine. The additional engine is not attached to the aircraft systems and does not generate any thrust. It is merely dead weight that is brought along for the ride.
“It’s very rare but we can do it. It’s an engineering feat that has been done by Qantas for many years.” said a Qantas spokesperson in 2016 when the airline carried out its most recent ferrying operation from Sydney to Johannesburg.
Qantas has employed this trick at least three times throughout its history: in 1989, 2002 and 2016. It first happened when a Qantas 747 flew from London to Sydney with an additional engine, achieving a world record for the longest non-stop flight by a commercial aircraft at the time. The first occasion was when a Qantas 747 traveled from Los Angeles to Auckland carrying an additional engine, following another Qantas 747 engine failure over the Pacific Ocean.
The ferrying method is subject to special permission from aviation authorities and entails meticulous weighing, balancing and aerodynamic calculations. The additional engine would put an additional 500kg drag on the aircraft and increase fuel consumption by some 3%. It also generates additional noise and vibration for the crew and passengers.
It was a very interesting sight to see an aircraft with five engines. It looked like a rocket. a Qantas pilot who operated the 1989 ferrying flight said.
The Boeing 747 is among the very few commercial aircraft capable of having an additional engine mounted on its wing. All other aircraft, including the Airbus A380 or the Boeing 777, have to carry spare engines by freight or smaller aircraft to transport them.
The ferrying technique is not only a cost-effective way of delivering spare engines, but also a testament to the engineering marvel and versatility of the Boeing 747, which has been in service for more than 50 years.
