B737-700/800/900 Fuel System - Engine
Fuel is delivered under pressure from fuel pumps located in the fuel tanks.
The fuel flows through a fuel spar shutoff valve located at the engine
mounting wing stations. The fuel passes through the first stage engine fuel
pump where pressure is increased. It then passes through two fuel/oil heat
exchangers where IDG oil and main engine oil heat the fuel. A fuel filter
then removes contaminants. Fuel automatically bypasses the filter if the
filter becomes saturated. Before the fuel bypass occurs, the fuel FILTER
BYPASS alert illuminates on the fuel control panel.
The second stage engine fuel pump adds more pressure before the fuel
reaches the Hydro Mechanical Unit (HMU). To meet thrust requirements,
the Electronic Engine Control (EEC) meters fuel through the HMU.
The spar fuel shutoff valve and engine fuel shutoff valve allow fuel flow to
the engine when both valves are open. The valves are open when the
engine fire warning switch is in and the start lever is in IDLE. Both valves
close when either the start lever is in CUTOFF or the engine fire warning
switch is out. SPAR VALVE CLOSED and ENG VALVE CLOSED lights
located on the Fuel Panel indicate valve position.
Fuel flow is measured after passing through the engine fuel shutoff valve
and is displayed on the display unit. Fuel flow information is also provided
to the Flight Management System (FMS).
The fuel flows through a fuel spar shutoff valve located at the engine
mounting wing stations. The fuel passes through the first stage engine fuel
pump where pressure is increased. It then passes through two fuel/oil heat
exchangers where IDG oil and main engine oil heat the fuel. A fuel filter
then removes contaminants. Fuel automatically bypasses the filter if the
filter becomes saturated. Before the fuel bypass occurs, the fuel FILTER
BYPASS alert illuminates on the fuel control panel.
The second stage engine fuel pump adds more pressure before the fuel
reaches the Hydro Mechanical Unit (HMU). To meet thrust requirements,
the Electronic Engine Control (EEC) meters fuel through the HMU.
The spar fuel shutoff valve and engine fuel shutoff valve allow fuel flow to
the engine when both valves are open. The valves are open when the
engine fire warning switch is in and the start lever is in IDLE. Both valves
close when either the start lever is in CUTOFF or the engine fire warning
switch is out. SPAR VALVE CLOSED and ENG VALVE CLOSED lights
located on the Fuel Panel indicate valve position.
Fuel flow is measured after passing through the engine fuel shutoff valve
and is displayed on the display unit. Fuel flow information is also provided
to the Flight Management System (FMS).
Fuel System SGR
