When the centre pump switches are OFF, the low pressure lights and EICAS messages for the pumps are inhibited. If the left or right main tank pump switches are OFF, the low pressure Lights are illuminated and EICAS messages for the pumps are displayed. If any pump has low output pressure, the appropriate switch PRESS light illuminates and the pump pressure EICAS message (eg L FWD FUEL PUMP) is displayed. To prevent the centre tank fuel pumps dry-running, a modification is in hand to automatically shutoff a pump if the associated fuel pump pressure transmitter detects low output pressure for 14 seconds.
#Fuel system indicators generator
(As installed) The right fuel override pump will supply fuel if both AC buses fail and the hydraulic motor generator comes on. As an engine is started and N2 RPM increases above 50%, the inhibit is removed for the associated centre tank pump. Thus both centre tank pumps are inhibited with the engines shutdown. To reduce electrical loads, the centre tank pumps are inhibited, both in flight and on the ground, when the associated N2 is Less than 50% RPM. When all six pumps are operating, the centre tank pumps override the left and right main tank pumps so that centre tank fuel is used before left and right main tank fuel. The two centre tank fuel pumps have approximately twice the output pressure of the left and right main tank fuel pumps.
A single pump can supply sufficient fuel to operate one engine under all conditions. Flight crew reset of tripped fuel pump circuit breakers in flight is prohibited.Įach fuel tank contains two AC-powered fuel pumps.
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