Airbus has chosen Honeywell’s HGT1500 auxiliary power unit (APU) to provide electric and pneumatic power for the new A350 variant of the A330 twin-aisle airliner, while Boeing has selected the company’s nitrogen-generation system (NGS) for the single-aisle 737.

The high-power density HGT1500 will power cabin conditioning and engine starting and be available for emergency power in flight up to an altitude of 41,000 ft. The U.S. equipment company suggests that installations of the APU, along with support, could be worth up to $4 billion.

The new APU provides the equivalent of 1,500 hp in the form of pressurized bleed air and electrical power. It uses a load-compressor architecture to deliver up to 2.86 kps of bleed air on the ground and in flight up to 25,000 feet.

The bleed air is primarily used by the aircraft environmental control system to ventilate and condition the cabin temperature and for starting the main engines. The APU can provide up to 150 kW of shaft horsepower to drive the gearbox-mounted electrical generator. It will be capable of starting and providing supplemental electrical power up to 41,500 feet. The HGT1500 will be ETOPS-certified to support long-range flight operations.

Honeywell’s 737 NGS separates oxygen from engine bleed air and uses the nitrogen to displace oxygen in fuel tanks, reducing the risk of explosion or fire. Four airline aircraft are being used for in-service evaluation of the system following earlier flight tests. The company now is planning to develop the NGS for other applications.

The unit uses micro fibers to produce nitrogen-enriched air by separating oxygen from conditioned engine-bleed air through components supplied  by Parker Aerospace. The nitrogen displaces oxygen in the fuel tank, reducing the risk of fires or explosions.