Fuel System Flashcards
Fuel is contained in ______________ fuel tanks.
crashworthy self-sealing
The fuel lines are designed to break between _____________, also minimizing spilled fuel if the cells break loose.
self-closing valves
The filler neck for the main tank is located on the _________ of the aircraft.
right side
The main fuel tank consists of __ fuel cells:
a. __ upright cells
b. __ underfloor cells
- 5
- 3
- 2
All 5 cells are _____________, allowing for free movement of fuel between the cells.
interconnected
The exact capacity is dependent on _________.
fuel type
Main fuel cells serviced with JP-8, hold ______ (______).
- 209 gal (1,400 lbs)
The 5 main fuel cells hold approximately __ hrs of fuel.
2
The underfloor cells are _______ by the upright cells.
gravity fed
Each underfloor cell is divided into forward and aft sections by a ______.
baffle
________ is minimized by the baffle and ensures a _____________ of fuel in the aft section.
- Sloshing
- constant supply
The baffle has a ______________ which allows fuel to flow only to the aft section.
one-way flapper valve
An ____________ in the forward section of each underfloor cell pumps fuel to the aft section.
ejector pump
____ aft aux fuel cells are installed in all Air Force N-models.
2
The left and right aux fuel tanks are located directly _________ the main upright cells and are accessible from _________ of the aircraft.
- behind
- each side
Each aft aux tank fuel cell has a ________ and a ___________.
- filler neck
- transfer pump
The capacity of the left aft aux tank (______) is slightly _______ than the right aft aux tank (______). This is due to the __________ available in the right aft aux tank compartment.
- 48.6 gal
- higher
- 41.4 gal
- limited space
When serviced with JP-8, the total capacity of the aft aux tanks is _____ (_____). This provides approximately __ additional hr of flight time.
- 90 gal (603 lbs)
- 1 hr
The fuel supply system consists of components used to deliver fuel to the engines. There is a separate but identical supply system for each engine.
Fuel is pumped from the underfloor cell by a ________. The fuel then passes through a _________. Fuel flows past a ___________, then through a ___________. The fuel then goes through a ______ mounted on the airframe.
Fuel then enters the engine fuel system.
- boost pump
- check valve
- crossfeed valve
- shutoff valve
- filter
Two ___________ boost pumps, 1 in the aft section of each underfloor cell, help to send fuel to the engines.
electrically driven
The __________ allows 1 boost pump to feed both engines.
crossfeed valve
The crossfeed valve is mounted to the ________ behind the ____________. It is electrically _______ and _______ by a switch in the cockpit.
- bulkhead
- main transmission
- opened
- closed
The __________ are used to control flow of fuel to the engines.
fuel shutoff valves
The shutoff valves are normally activated by the ______________ switches located on the center pedestal.
ENG 1/ENG 2 FUEL CONT
Both shutoff valves are located on the _______ behind the ______________.
- bulkhead
- main transmission
There are __ airframe mounted fuel filters. The filters remove contaminants from the fuel prior to delivery to the respective fuel control unit. Each filter has __________ provisions to assure fuel flow to the engine if the filter becomes clogged.
- 2
- internal bypass
Each main fuel switch has an ON and OFF position.
a. ON position
1) Opens respective engine's
\_\_\_\_\_\_\_\_\_ valve.
2) Turns on both engines'
\_\_\_\_\_\_\_ pumps.
3) Energizes engine
\_\_\_\_\_\_\_\_\_\_.
4) Energizes \_\_\_\_\_\_\_\_\_\_\_\_\_\_.
b. OFF Position
1) Closes respective engine's fuel
\_\_\_\_\_\_\_\_\_\_.
2) Allows both \_\_\_\_\_ pumps to
continue to run until both Main
Fuel switches are switched to
OFF.ON:
- fuel shutoff
- boost
- ignition circuits
- fuel control sense line heaters
OFF:
- shutoff valve
- boost
There are 3 positions for each aux fuel xfr pump switch:
a. FWD position:
Not used
b. OFF position:
Aux fuel transfer pump off
c. AFT position:
Aux fuel transfer pump \_\_\_\_\_\_\_\_energized
The ___________ displays the amount of fuel in the main tanks. There are __ probes in the main tanks that provide readings.
- Fuel Quantity Indicator (FQI)
- 5
Each bar segment in the FQI is equal to ___
10%
The R LOW and/or L LOW caution lights on the fuel system caution panel are activated by 2 low-level sensors, 1 in the aft section of each underfloor cell. These caution lights indicate that _________ of fuel remain in the respective aft compartment underfloor cell.
160 +/- 40 lbs
T/F: The auxiliary fuel tanks have a fuel gauge mounted on the instrument panel.
False
Aux Fuel Transfer Normal Operations:
Fuel transfers at:
a. _____ with 1 pump on
b. _____ with both pumps on
Fuel line diameter limits the transfer rate to \_\_\_\_\_ when both pumps are operating.
- 25 Ppm
- 40 Ppm
- 40 Ppm
___________ in the aft center main fuel cell actuate
the transfer pump(s) and prevent the main fuel cells
from overfilling when the transfer pump(s) are on.
Fuel level sensors
The fuel level sensors cycle the selected transfer
pump(s) on and off.
a. On at __________
b. Off at __________
- 1,130±50 lbs
- 1,290±50 lbs
When the AUX FUEL LOW/AUX LOW lights illuminate, switch selected pump to OFF. Approximately ___ gal of fuel will remain in the unselected tank due to interconnect line placement. Select this tank’s aux fuel transfer pump to transfer the remaining __ gal to the main tank.
5
Center of Gravity (CG) shifts ______ as the aux tanks empty. Begin aux fuel transfer as soon as possible to preclude unprogrammed CG shift.
forward
Which switch would you press to test the fuel system caution panel lights?
LAMP TEST switch
Which switch would you press to test the LCD on the FQI gauge?
BIT switch
A fuel imbalance may be caused by:
- Boost pump failure
Fuel is not being pumped from the underfloor cell. - Ejector pump malfunction
Fuel is not being pumped over the baffle to the rear portion of the cell. - Flapper valve failure
Fuel is not able to pass through baffle to the aft section of the cell. - Blocked interconnect line
Blocked line prevents equalization of fuel between the underfloor cells and proper gravity feeding of fuel within the cells.
Fuel Imbalance - Corrective Action:
- Set airspeed to ________ and _________.
- If condition persists: Land _____________.
- 70 to 80 KIAS/level attitude
- as soon as practical
T/F: If both boost pumps fail, flight above 4,600 ft MSL may result in dual engine flameout.
True
Illumination of a fuel filter caution light segment is an indication of __________.
a corresponding airframe mounted fuel filter is clogged and a bypass condition is impending
