All engines have limits to the maximum power which may be obtained. This may be dictated by the power transmission capability of the engine and gearbox or physical limits on rotational velocity and temperature to restrict turbine blade creep to an acceptable level. To accommodate this requirement it is customary to use mechanical governors or a Full Authority Digital Electronic Control. However, the mechanical solution suffers from eventual deterioration due to wear, while the electronic approach requires certification to FAA Critical Levels.
A solution has been to develop an electronic limiter, which controls the fuel control governing pressure (Py) of a conventional mechanical fuel control in order to meet the design limits of the engine. This paper will describe one such limiter developed by Avelex for aerobatic turboprop engines.