Patent ID: 9470152
Filing Date: 2016-10-18
CPC Classification: F02C,F05D

Claim Text:
1. An engine fuel control system including: a fuel metering valve operable to control a flow of fuel between a supply line and a delivery line, a pressure drop control arrangement operable to regulate a pressure drop across the metering valve, the pressure drop control arrangement maintaining in normal use a substantially constant pressure drop across the metering valve, an electro-mechanical backup control system which, in the event of an engine overthrust event, is controllable by an electrical pullback signal to operate the pressure drop control arrangement, such that increasing the pullback signal reduces the flow of fuel between the supply line and the delivery line, a detector arrangement which detects a start of an engine overthrust event, and detects a time at which an upward runaway caused by the overthrust event is arrested, and a controller which (i) determines, at the time of the overthrust detection, a rate of increase of the pullback signal and an offset of the pullback signal, (ii) sends the pullback signal to the backup control system at the determined rate of increase, and (iii), when the upward runaway is arrested, reduces the pullback signal sent to the backup control system by the determined offset.