Chapter 12 – Fuel System Flashcards
- What is the maximum amount of fuel we can carry in pounds with a fuel density of 6.7lbs per
gallon?
a. 359,414lbs (AOM 12-9)
- With the A/C completely full of fuel, discuss the different fuel configurations beginning with
engine start through landing?
a. All Boost Pump switches are on. Ovrd/Jett pumps 2&3 are Armed. CWT feeds all engines. (Center to all)
b. When flaps reach 10° xfeed valves 2&3 close (Center to 1 and 4, Inboard to Engine)
c. After Takeoff when the flaps are up, crossfeed valves 2&3 are commanded open (Center to All)
d. In Climb, if FUEL LO CTR L/R message is displayed (tank quantity is approx. 7,000#)
select CWT pumps to off (Inboard to All)
e. In cruise when FUEL OVD CTR L/R is displayed and tank quantity is 4,000# or more, CWT Pumps should be selected back on. Center to All)
f. When FUEL LOW CTR is displayed and CWT is less than 3,000# pumps should be selected off. Ovrd/Jett pumps 2&3 activate when CWT pumps are selected off. (Inboard to all)
g. With approx. 40,200# in main tanks 2&3, the reserve tank transfer valves open allowing fuel to gravity transfers to main tanks 2&3, and a scavenge pump activates in the CWT and scavenges fuel to main tank 2.
h. When all tanks are equal in quantity (Approx 29,000#) FUEL TANK/ENG is displayed.
Override/Jet pumps should be selected off and crossfeed valves 1&4 closed. All main pumps are now feeding respective engines. (Tank to Engine)
- How do we, and what happens when, we jettison fuel?
a. Jettison is initiated by rotating jettison selector knob to A or B. When A or B is selected fuel temp is replaced by “To Remain”
b. If a failure occurs in one channel you must select the other channel
c. Jettison time to dump is displayed on fuel synoptic
d. Allow 90 sec. for system to calculate dump time
e. Rotating fuel to remain knob decreases or increases quantity
f. Pushing either jettison nozzle valve switch on activates all ovrd/jett pumps in the tanks
containing fuel (pump switches must be on)
g. Jettison control system controls fuel balancing between tanks 2&3
h. If balancing is required ovrd/jett pumps in low tank deactivate until tanks are balanced
i. Reserve transfer valves open when main tanks 2 or 3 qty is decreased to 40,000#. Fuel transfers from reserve tanks 2&3 to respective main tanks
j. When either main tank 2 or 3 qty decreases to 20,000# during jettison both main tank
1&4 transfer valves open Jettison terminates when fuel to remain has been reached Fuel to remain qty changes color from magenta to white and flashes for 5 seconds, Jettison control system deactivates all operating pumps
- What is the difference between total fuel and calculated fuel? When are the values
different?
a. Total Fuel is the fuel onboard as indicated by the Fuel QTY System
b. Calculated Fuel = Before start Total Fuel – fuel burned as measured by fuel flow signal rate.
c. Fuel Leak (AOM 11-131)
- Prior to engine start, with usable fuel in the CWT, after fuel pump configuration are the
2&3 Override/Jettison pumps on or armed?
a. Armed (AOM 12-14)
- What is the purpose of the #1&4 transfer valves?
a. Fuel gravity transfers from outboard to inboard main tank to approx. 7,000# remaining
in each outboard main tank
b. During fuel jettison, the valves open when either main tank 2 or 3 fuel decrease to
20,000#
c. Valves may be opened manually using the Fuel Transfer Main 1&4 switch on overhead
panel (AOM 12-14)
- Does the flow bar disappear in the cross feed #2&3 valve switches when the flaps are
selected to the TO position?
a. No (AOM 12-1)
- After positioning the fuel jettison selector to A or B where does the fuel jettison value
display?
a. Replaces Fuel Temp on Primary EICAS (AOM 12-16)
- Once activated, how long will the scavenge pump operate?
a. Until the pressure switch for the fuel scavenge pump senses low pressure, or the total
time of pump operation exceeds 120 minutes (AOM 12-15)
