As in many other branches of engineering, progress in propulsion controls has, for the past 30 years, meant the increasing application of electronics.

Throughout this period, the whole Aero-Engine Industry has used electronics to perform various limiting functions, particularly in the form of jet-pipe temperature limiters. However, Rolls-Royce and the British Controls Industry are undoubtedly the pioneers in the radical application of electronic technology to the control of aero gas turbines. World-wide, there are still only two aero engines in civil operation today with ‘Full-Authority’ electronic controls. They are:

The Rolls-Royce Proteus turboprop which has accumulated seven million hours in the Britannia since its entry into service in 1957. Its pre-transistor Ultra system still uses magnetic amplifiers and has achieved a very high reliability indeed, (in-flight shut-down rate = four per million engine hours).