| 摘要 |
A fuel control system for gas turbine aeroengine includes an overspeed limiter unit operative to limit fuel flow when engine speed exceeds a predetermined safe value. It is conventional for such overspeed limiters to be activated only in the event of an overspeed, so as to obviate the possibility that the limiter unit may fail unnoticed while the unit is dormant, the invention utilises the limit unit as an active part of the fuel control system on a continuous basis. Specifically, the overspeed limiter unit is used to control the pressure drop across a fuel metering unit as a function of engine speed, except when it is actually performing its overspeed limiting task. Specific means of accomplishing this are disclosed. In this way, any failure in the limiter unit will be immediately apparent due to its effect on the functioning of the system, and appropriate action can be taken.
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