Ian Sheppard/LONDON
Ultra Electronics has successfully test flown a propeller de-icing system which avoids the need for a slip-ring contact assembly, offering potential maintenance savings of several thousand dollars an engine a year.
Flight testing took place in Wichita, Kansas, from 13-18 May with the Hub Integrated Power and Switching System (HIPSS) installed on the Raytheon Beech 1900D UE-1 test aircraft, which is powered by Pratt & Whitney Canada PT6A-67Ds driving four-bladed Hartzell propellers.
After the first 5h of proving flights, the prototype was delivered to P&WC for further work with its PT6 test rig, while a second prototype system is being prepared for fitting to another aircraft for more certification testing.
The Cambridge, UK-based company is preparing an application for a supplementary type certificate (STC) from the US Federal Aviation Administration, the trials for which could start in two or three months and be complete in six months. Ultra hopes the system will be commercially available in "around one year" for retrofit.
Based on figures supplied by operators of the 1900D, system maintenance costs $5,000-7,000 per year per engine, given that the slip rings are cleaned about 30 times and the silver-loaded brushes replaced twice in a typical year of 3,000 annual flying hours. The HIPSS, based on a mean time between failures of 20,000h, costs $300-600, claims Ultra.
Purchase price depends on the application, says the company, with aircraft as big as the Lockheed Martin C-130 being looked at. Ultra has a "study contract" with the US Navy and propeller manufacturer Hamilton Standard, which could make the C-130 the next application to win approval.
The system comprises three subassemblies: an airframe mounted control unit (in new cast housing), a permanent magnet generator and a hub-mounted electronic module. The generator has two parts: a static magnet mounted to the gearbox and a rotating magnet integrated with the electronic module, which is fitted to the mounts vacated by the slip rings.
Communication between the static and rotating electronics is achieved by modulating the generator's magnetic field. For retrofits, the system is wired into the existing flightdeck instrumentation.o
Source: Flight International
