Toulouse, France-based Microturbo is here exhibiting a mockup of its e-APU, a new-generation auxiliary power unit that is currently undergoing ground trials. According to company engineers, the first test results are showing “excellent overall dynamic behavior.”

The e-APU has been designed for in-the-works business jets with increased electric power needs. Since its first run last December 31, the e-APU has exceeded its nominal power. It also has completed tests for fuel control adaptation, thermal and dynamic behavior and some transient operations. Instrumentation measured about 100 test points. Analysis has confirmed that objectives have been met. A second turbomachine has now just been added to the tests.

The e-APU has been designed with maintainability in mind, thus cutting direct maintenance costs by an expected 20 percent compared to most in-service auxiliary power units. Customers will get true on-condition maintenance, according to Microturbo.

Another improvement is the power-to-weight ratio, which has been doubled. Moreover, the pressure ratio has been increased to seven, thus delivering more efficient combustion.

The e-APU’s turbomachinery is made of a single-stage centrifugal compressor and a two-stage turbine. The new APU should also be more environmentally friendly, with reduced fuel burn, lower emissions and quieter operation–below 70 dB.

For five-ton-plus business aircraft, including helicopters, the e-APU will offer an electric power output of 15 to 90 kWe (up to 150 shp), enabling electric engine starts. The e-APU will be able to start at altitudes up to 41,000 feet and operate at up to 51,000 feet.

Microturbo (Booth No. 5152) said its e-APU has been selected on two unnamed aircraft programs. The Safran Group firm plans to deliver the first production examples early in 2012 to one aircraft manufacturer.