ALLIEDSIGNAL AND Raisbeck Engineering are in preliminary talks on the possibility of fitting external auxiliary power units (APUs) to business jets.

The companies' scheme would allow an AlliedSignal APU to be attached to the rear fuselage of an aircraft without cutting into the structure.

The APU would then be covered with a rear-fuselage fairing similar to Raisbeck's Lear Locker (Flight International, 19-25 April), which is used to provide additional luggage-storage space in the Learjet 31 series.

Raisbeck chief executive James Raisbeck says that the first fit is likely to be to the Raytheon Aircraft Hawker 800 and the British Aerospace 125-700. He also predicts potential applications for the new Learjet 45.

Raisbeck expects, however, that it will take "a minimum of two years" before the modification can be offered to the market.

The modification will weigh about 80kg, including the APU, but the fairing will reduce the aircraft's aerodynamic drag. The Lear Locker fairing has been shown to produce a 4% drag reduction on the Learjet 31 at Mach 0.7.

The cost of the modification is expected to come to about $180,000.

Source: Flight International