Airline fuel savings of 4 percent and quieter, cleaner airports are predicted for an electrically powered “green” taxing system for airplanes being developed by Safran and Honeywell. The two companies signed a memorandum of understanding (MOU) on Sunday to form a joint-venture company to develop the system.

In operation, electric motors mounted on each of the main landing gear bogies would power the wheels from the ramp to a point near to the runway, eliminating the need to taxi with the main aircraft engines at idle, running inefficiently and often for a considerable time.

Power for the electric motors would come from the aircraft’s existing auxiliary power unit, which is also a jet-fuel-burning turbine engine. But APUs are much smaller than the main aircraft engines and therefore burn much less fuel. Nevertheless, while the proposed system is described as “electric” and “green,” it will not be completely either one.

Pilots would operate the system using cockpit controls, which have not yet been defined. “We’re working with the manufacturers on cockpit philosophy,” said a Honeywell spokesman. “Pilots will feel no difference in the way the aircraft behaves.”

Short-haul airlines would reap the maximum benefit, as taxiing accounts for a larger proportion of the total engine running time, consuming up to five million tons of fuel a year. While single-aisle airliners, such as the A320neo, would be the first application, the taxi system would eventually be available for all major airliner types.

The two companies say the MOU will enable them to get it to market as rapidly as possible. Initial development began in January, and prototypes will be fitted to an Airbus A320 testbed by mid-2013, with service entry set for 2016.

The taxi system (which has yet to be named) will be available for both new and retrofit aircraft, but Honeywell and Safran were unable to confirm what likely costs would be, or how long it would take to achieve payback on the initial investment. They said only that it would save airlines “several hundred thousand dollars a year per aircraft.”

Other advantages of the system include no requirement for tow trucks, reducing time, less use of brakes during taxing, noise and pollution reduction at the ramp, improved safety for ground personnel and reduced ingestion of foreign objects while taxiing.

Both companies told AIN they think the deal will pave the way for further joint enterprises. “We’ve found we get on really well together,” said Safran chairman and CEO Jean-Paul Hertemann.  The companies are perfectly matched for the enterprise, he said, explaining that Honeywell brings its APU experience and Safran its knowhow on landing gear, wheels and brakes.

Together the “companies will bring their expertise in electric power, mechanical systems and system integration, as well as their combined credibility for innovation,” Hertemann added.