Electric taxi specialist WheelTug has yet to determine a service entry date for its nose wheel drive system, as the Gibraltar-headquartered engineering firm will have to certificate the equipment without support from Airbus and Boeing.
From the current stage, it will take between 18 months and two years to complete the development and gain system approval, says WheelTug chief executive Isaiah Cox. This would depend on gaining access to Airbus and Boeing’s engineering data for their respective A320 and 737 families. But “Boeing and Airbus do not support the [WheelTug] programme”, says Cox.
While the engineering firm has raked up nearly 800 tentative orders from 14 airlines for its design – including both 737 and A320 operators – the European airframer rejects the idea that a nose wheel drive system could manoeuvre aircraft on the ground without the main engines. “Airbus and our landing gear colleagues [suppliers] do not support the concept of putting an electric motor on the nose gear,” says the airframer, which has weighed in behind the “Electric Green Taxiing System”, a main landing gear drive system being developed by Honeywell and Safran.
WheelTug is now following an alternative strategy that will require no support from Airbus and Boeing, says Cox. The final pre-serial production phase should be started in the “next couple of months”, with certification due to follow in late 2015 or early 2016. A conference about the entry-into-service schedule is to be held in Prague in September.
WheelTug had aimed to certificate the system by the end of 2013. However, Cox says “our certification deadline has always been rolling”, being dependent on access to data.
Although different system demonstrators have been tested on 737s, it is not clear whether the production model will first be introduced for the US narrowbody or the A320. WheelTug trialled a prototype version on a Germania 737-700 at Prague airport in June 2012. That equipment featured integrated motors in the nose wheels, while previous tests on another 737 and 767 involved motors installed outside the wheels.
No equipment tests have yet been undertaken on an A320. Industry sources have highlighted that the installation on the European type will be more challenging than on the 737, because the A320’s centre of gravity is further aft than on its competitor model. Another complication is the A320’s slightly angled nose gear leg which, when fully deflected, causes one of the two wheels to come off the ground.
Cox says traction on the wheel that stays on the ground will increase, because the weight on the nose landing gear will not change. While there are “advantages and disadvantages with both of them”, he insists that the 737 and A320 pose “approximately the same challenge from a technical perspective”.