Green aircraft taxiing gathers momentum as Safran and Honeywell roll out first public demo of EGTS
The EGTS-equipped Airbus A320 test aircraft
Thu 20 June 2013 – The Safran/Honeywell electric green taxiing system (EGTS) made its first public demonstration at the Paris Air Show this week following completion of the first major phase of testing. The EGTS International joint venture was first announced at the same show two years and the component system and aircraft testing programme has now accumulated over 3,000 hours and logged close to 160 kilometres (100 miles) of rolling tests, including complex on-ground manoeuvres such as pushback, tight turns and U-turns on a modified Airbus A320. On Monday, Air France joined the programme to provide assistance in refining estimated fuel and emissions savings of the system and quantifying other operational benefits. The French and US partners estimate an equipped single-aisle aircraft could reduce carbon emissions by around 75 per cent and NOx emissions by 50 per cent during taxiing. Meanwhile, EGTS rival WheelTug says it has now racked up 573 delivery slots reserved by 11 airlines for its competing aircraft drive system.
Honeywell and Safran are targeting EGTS entry into service on new aircraft in 2016, shortly followed by a retrofit option on existing aircraft.
The EGTS allows aircraft to taxi without requiring the use of aircraft engines by using the Auxiliary Power Unit (APU) generator to power motors in the main wheels. Each of the aircraft’s powered wheels is equipped with an electromechanical actuator, while unique power electronics and system controllers give pilots total control of the aircraft’s speed, direction and braking during taxi operations, negating the need for ground equipment to manoeuvre aircraft in and out of stands. By reducing the use of aircraft engines, there is also an added benefit in terms of less airport noise.
Safran test pilot Jens Berlinson says the revolutionary system, with faster pushback time capability due to its fully autonomous reverse mode, will bring immediate benefits for a pilot operating in congested airports. “With EGTS, we no longer need to use the brakes unlike with today’s aircraft that have a tendency to accelerate naturally even when the engines are at idle,” he adds. “This is especially valuable at busy airports where planes are often queuing up for an extended period of time before take-off.”
According to the partners, because an aircraft’s main engines are optimised for flying rather than taxiing, they burn a disproportionate amount of fuel during ground operations. With a short or medium range aircraft spending up to 2.5 hours of its time on taxiways every day, EGTS could save around 600kgs of fuel used during taxiing daily, they estimate.
“EGTS will be for aviation what hybrid cars were for the automotive industry,” claims Brian Wenig, EGTS Program Vice President, Honeywell Aerospace. “The potential of fuel savings and emissions reductions that can be had with the system will be monumental for airlines.”
Added Olivier Savin, EGTS Program Vice President, Safran: “EGTS clearly demonstrates the multiple benefits gained from a system that combines concrete cost savings with significant emissions reductions for the benefit of airlines, airports and ultimately passengers.”
The next phase of the test programme will be to conduct manoeuvres at speeds up to 20 knots, at full performance and with the aircraft at maximum take-off weight (MTOW).
As Air France utilise a number of heavily used airports, the EGTS can provide a decisive economic advantage at these airports, while also reducing emissions and noise in the terminal environment, says the airline. From early analysis, Air France expects to save the equivalent of several per cent fuel burn per cycle based on current operations for its fleet of 120 or so short and medium range aircraft.
Also exhibiting at the Paris Air Show is Gibraltar-based WheelTug, whose aircraft drive system similarly uses the APU to power high-performance electric motors installed in the nose gear wheels to provide full mobility while on the ground, without the need for aircraft main engines or pushback and taxi operations.
Typically, a taxiing Airbus A320 or Boeing 737NG aircraft burns 24 to 27 pounds (10.9-12.2kgs) of fuel per minute, says WheelTug, but claims its system needs only four pounds of fuel per minute, representing an 80% reduction in ground operations fuel consumption. When all the attendant cost benefits are added up, WheelTug estimates total savings of over $700,000 per aircraft per year.
The system is being offered to airlines entirely on a lease, or power-by-the-hour, basis so that it can be installed without capital expenditure required by the operator.
Recent Slot Purchase Agreements have been signed with Air Berlin, with 110 reservations, and Icelandair, which becomes the first carrier to reserve delivery slots for the Boeing 737 MAX aircraft. WheelTug’s order book now totals 573 slots reserved by 11 airlines from Europe, America, the Middle East and the Far East.