Engine SGR
Engine Fuel System
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 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
overhead 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 FMS.
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 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
overhead 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 FMS.
B737-700/800/900 Engine
Engine Oil System
Oil from the individual engine tank is circulated under pressure, through the engine to lubricate
the engine bearings and accessory gearbox. The oil quantity indicator, oil temperature indicator,
oil pressure indicator and LOW OIL PRESSURE alert are all located on the display unit.
The oil system is pressurized by the engine driven oil pump. Oil from the pump goes to the engine
bearings and gearbox. Sensors for the oil temperature indicator, oil pressure indicator and LOW
OIL PRESSURE alert are located downstream of the oil pump prior to engine lubrication. Oil is
returned to the oil tank by engine driven scavenge pumps. From the scavenge pumps oil passes
through a scavenge filter. If the filter becomes saturated with contaminants, oil automatically
bypasses the filter. Prior to the oil bypassing the scavenge filter, the OIL FILTER BYPASS alert
illuminates on the upper display unit.
Prior to returning to the oil tank, the oil passes through the main engine oil cooler where it is
cooled by engine fuel to maintain proper oil temperature.
Oil from the individual engine tank is circulated under pressure, through the engine to lubricate
the engine bearings and accessory gearbox. The oil quantity indicator, oil temperature indicator,
oil pressure indicator and LOW OIL PRESSURE alert are all located on the display unit.
The oil system is pressurized by the engine driven oil pump. Oil from the pump goes to the engine
bearings and gearbox. Sensors for the oil temperature indicator, oil pressure indicator and LOW
OIL PRESSURE alert are located downstream of the oil pump prior to engine lubrication. Oil is
returned to the oil tank by engine driven scavenge pumps. From the scavenge pumps oil passes
through a scavenge filter. If the filter becomes saturated with contaminants, oil automatically
bypasses the filter. Prior to the oil bypassing the scavenge filter, the OIL FILTER BYPASS alert
illuminates on the upper display unit.
Prior to returning to the oil tank, the oil passes through the main engine oil cooler where it is
cooled by engine fuel to maintain proper oil temperature.
