757 Fuel Systen Flashcards
What is displayed in the main tank indicator during the fuel quantity test?
88.8
The APU is powering the aircraft. Which pump is supplying fuel to the APU?
The LEFT FORWARD boost pump
When does the DC fuel boost pump automatically start?
When the APU is started with battery power only
At flaps 25. When do the center pump LOW PRESSURE lights illuminate?
When the pump switches are on, and pump pressure is low
When does the total fuel value come from?
From the fuel quantity processor
There are boxes on the FUEL QUANTITY line of he performance/initialization page. What does this mean?
The FMC is not receiving valid fuel quantity data, and the quantity must be manually entered.
He APU is running on the ground. Can you turn off the left forward fuel pump?
No… There is an override circuit which keeps the pump operating.
What does the FUEL CONFIG and/or LOW FUEL light mean?
Left or right main tank less than 2200 lbs
Fuel temperature is taken from?
Sensor in the right main tank
How many fuel pumps per tank?
Two AC powered pumps. Left tank has an additional DC pump for APU start when no AC power on the airplane
What is the pump priority?
Center tank then main tank. Center tank pumps have a higher output pressure
What happens when a pump has low output pressure?
The affiliated switch light “PRESS” light illuminates along with EICAS message
What happens below 50% N3?
The center tank pumps are inhibited to reduce electrical loads. Both venter tank pumps are inhibited when engines are shutdown
How is APU FUEL feed controlled?
APU is supplied by the left fuel manifold
When APU is turned on and no AC power is available, fuel is provided by a DC pump in the left fuel tank
When AC power is available, the left forward AC fuel pump operates automatically regardless of pump switch position
757 Total fuel capacity
75,000 lbs
757 center tank fuel capacity
46,000 lbs
757 left and right tank fuel capacity
14,500 lbs
Minimum fuel temperature
-45 C
Emergency fuel
5,000
FUEL CONFIG light
Left and right tanks differ by 1800
Center tanks switches off with more than 1200 lbs in center tank
Low fuel quantity- LOW FUEL EICAS message
FMS CDU FUEL message
INSUFFICIENT FUEL - predicted fuel at destination is less than FMC reserve fuel
FUEL DISAGREE PROG 2 - fuel totalizer and calculated fuel quantity disagree
How many FUEL EICAS messages are there?
13
How is unusable fuel in the center tank handled?
Center tank fuel scavenge system operates. Transfers fuel to the left main tank.
Begins when the left main tank is approximately half empty
What pumps provide fuel to the APU?
A dedicated DC pump or the left forward AC fuel pump when AC power is provided
What does the fuel totalizer do?
It gives an independent calculation
On what page of the FMS are the zero fuel wights and reserves entered?
PERF INT page
On what page of the FMS can totalizer and calculated fuel be found?
PROG page 2
What is the purpose of the fuel cross feed valves?
To enable any pump to feed any engine
What 3 conditions will cause the FUEL CONFIG light to illuminate?
- Fuel in the center tank with the center tank pumps off
- Differences between the main tanks
- Low fuel in either main tank
How is the center tank fuel used before main tank fuel with all pumps on?
Center tank pumps have a higher output pressure than the main tank pumps.
When do the center tank pumps operate with pump switches on?
When the respective engine is operating above 50% N3
757 approximate fuel
Left main. 14.5
Right main. 14.5
Center. 46.0
Total. 75.0
