Paris Air Show: Aircraft tech that works best on the ground

image captionThe system, which is likened to the one in a hybrid car, was demonstrated at the Paris Air Show

Amid the fighter jets' screaming overhead and the gleaming new airliners, an old Airbus A320 was getting a lot of attention during Paris Air Show week.

The aircraft didn't fly, and it didn't fire up its engines. But it did move very slowly. And this was what was drawing the crowds.

Sometimes a product comes along that makes you ask, why wasn't this on the market years ago?

Two years after going into partnership, Honeywell and Safran, two of the biggest names in aviation technology, have brought their Electric Green Taxiing System (EGTS) to the air show.

It is a complicated piece of advanced engineering that can be summed up simply.

A control unit is fitted to the wheels, which draws its power from the aircraft's electrical system rather than the main engines. So, when the aircraft is taxiing at the airport it is not wasting expensive fuel.

It is a little like a hybrid car using two power sources to increase efficiency.

image captionMotors attached to the landing gear are powered by the plane's electrical system

The result? Lower emissions and operating costs, extended engine life and reduced noise.

Test trials

At least, that is what Brian Wenig, vice president of the EGTS programme at Honeywell Aerospace, says. He estimates that the fuel saving on an A320-type aircraft would be 3% to 4%.

"It will dramatically reduce fuel consumption and lower operational costs," he says. "And the system would therefore reduce, if not remove altogether, the need for aircraft ground equipment to manoeuvre in and out of stands."

Honeywell and Safran believe that the system could save airlines around $200,000 (£129,000) a year per aircraft in fuel costs.

Air France is one of the airlines about to investigate whether all of these claims stack up.

The French national carrier announced at the air show that it would analyse the potential technical, operational and financial benefits of EGTS.

That is a major breakthrough for a system that sounds simple but clearly is not. During the show, the makers used an old Airbus to demonstrate that the pilot could remain in full control of the heavy aircraft while doing taxiing manoeuvres using the power drawn from the electrical system.

The EGTS is not the only system currently under development, with L-3 and WheelTug working on similar products.

Meanwhile, Israel Aircraft Industries has its TaxiBot system, which makers claim has the added advantage that it can be used to control far larger, wide-body aircraft.

But Honeywell and Safran feel they have managed to steal a march on rivals by being able to demonstrate EGTS successfully under the prying eyes of observers at the world's largest aerospace event.

image captionEngines burn a disproportionate amount of fuel while taxiing

Revenue drain

Before the Paris show, the system had, in fact, been put through about 100 miles of runway tests. The next stage is to do the tests at greater speeds and under maximum take-off weight.

Obviously the EGTS is a sophisticated piece of kit, but it was airlines' demand for fuel efficiency, rather than any major technological breakthrough, that persuaded Honeywell-Safran to pour tens of millions of dollars into the project.

The development of Boeing's 787 Dreamliner and Bombardier's forthcoming C-Series were also driven by customers' needs to cut back on sky-high fuel costs.

media captionTheo Leggett takes a look at Agusta Westland's Project Zero

Mr Wenig says: "Airlines' requirement for fuel-efficient technology is now paramount. Fuel costs are an ever-increasing drain on airline revenues and profits, counting for as much as 50% of airlines' direct operating costs in some parts of the world.

"The EGTS is attached to existing landing gear with only minor modifications, mitigating the need for time consuming hardware replacement of the entire landing gear architecture," he says.

Airline engines are made for flying, not idling at the departure gate waiting for a take-off slot.

For a medium range aircraft, which is used several times a day, the problem is magnified. That's because they will burn a disproportionate amount of fuel than a jumbo jet that is in the air for longer on fewer flights.

"A single-aisle aircraft operates, on average, 2.3 hours on the ground over eight to 10 daily rotations, resulting in considerable fuel burn before the aircraft has even left the ground," Mr Wenig says.

And for an airline such as Air France, with a fleet of 120 short and medium-range aircraft, the savings would be huge. There are about 10,000 single-aisle aircraft in service, with Honeywell-Safran claiming that its potential market for EGTS is for about 80% of these.

Mr Wenig says the system is on track to be ready for use in 2016, with a retrofit option for existing aircraft coming to the market soon after.

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