AlliedSignal has revised its recent systems agreement with Raytheon Aircraft for the Hawker Horizon to cover the development of a single integrated pneumatic controller (IPC) which effectively links the auxiliary power unit (APU) and the environmental-control system (ECS) to act as a single system.

The IPC is believed to be a first for any business jet and "enters the realm of a new product", says Barry Gillespie, director of AlliedSignal business aviation and regional airline APU programmes. Under the revised deal, AlliedSignal will have full responsibility for the installation, design and integration of the 36-150(HH) APU, rather than simply supplying the "dressed" engine to the assembly line in Wichita, Kansas.

The other significant feature of the expanded contract is the provision of a single electronic controller for the ECS and APU. "The APU will know what the ECS wants, so we will get this talking back and forth," says Gillespie. "It will drastically increase overall system performance as well as increase the reliability of the controller because you are reducing the number of boxes involved from five or six to just one."

The ECS work, provided by AlliedSignal's Aerospace Equipment Systems division, includes installation of aircraft ducting and mounting hardware, as well as the fuselage portion of the anti-icing systems, air-conditioning, pneumatic air and cabin pressurisation. The APU portion, provided by the company's Engines division, includes inlet and exhaust ducting, mounting structure and wiring.

I expect the development to flow out to commercial propulsion," says Gillespie. "Every major original equipment manufacturer is enquiring about this."

The integrated system weighs 4.7kg, representing a 35% saving over the conventional approach. Overall volume is also decreased by 36% while mean time between failure is up to 14,000h - or roughly a 186% improvement.

Source: Flight International