Electric APU set to enter service on AW189
The AgustaWestland AW189 medium twin helicopter will be the first civil application for Microturbo’s e-APU, an auxiliary power unit that delivers essentially electric power. The e-APU60, which will deliver 60 kilowatts for the helicopter’s systems, offers benefits in safety, fuel burn and overall aircraft design, according to Microturbo.
The Toulouse-based equipment manufacturer would give details only for the military, shorter version of the AW189, the AW149, but AIN understands they also apply to the AW189. The e-APU will provide power for de-icing and engine start. It can operate far above any helicopter’s ceiling, at up to 51,000 feet.
In case of one engine failure, the e-APU can feed the aircraft’s systems, thus alleviating some of the strain on the surviving engine, improving safety, said Jean-Baptiste Jarin, sales and customer director. In addition, it eliminates the need for manufacturers to oversize the engines, reducing weight and fuel consumption.
On the Anglo-Italian rotorcraft, it will also electrically power the vapor cycle system for cabin air cooling. To heat the cockpit and cabin on the ground, a modest air bleed has been added, with fans to mix the compressor’s air with ambient air. “This small bleed does not affect the e-APU’s performance,” Jarin said.
Microturbo claims the e-APU will have significantly lower maintenance costs compared with its conventional competitor. The new APU should also be more environmentally friendly, with lower emissions and quieter operation–below 70 dB.
The e-APU has already been ground tested extensively. Flight testing on the AW189 is to begin this year. In parallel, APU certification tests are going on and will be completed late next year. The AW189 is scheduled to enter service in early 2014.
The e-APU’s turbomachinery consists of a single-stage centrifugal compressor and a two-stage axial turbine. On a business jet, it can restart the engine at altitudes up to 41,000 feet, much higher than today’s common limit of 30,000 to 35,000 feet, Jarin said.