FUEL SYS Flashcards
What type of fuel system do we have?
crashworthy, suction-type system
What portion of the main tank is self-sealing?
the lower 1/3
What is the capacity of the main tank?
590 gallons or 4,012lbs. of JP-5
What is the interconnect level for the left and right tank?
270-600lbs.
How is the fuel weighed?
each tank has a fuel probe that is a capacitance-type sensor that employs fuel as a dialectic to measure the fuel weight
What creates the required suction to draw fuel from the cells?
the engine driven boost pump
Describe the fuel flow.
main tanks – fuel selector levers – engine driven boost pump – pressure sensor – fuel filter – HMU – fuel/oil heat exchanger – ODV – engine for combustion
What are the four main functions of the ODV?
- Provides main fuel flow to the 12 fuel injectors.
- Purges fuel overboard after shutdown to prevent coking in the injectors.
- Traps fuel upstream in the fuel/oil heat exchanger so that system priming is not required prior to the next start.
- Returns fuel back to the HMU if the Np overspeed protection is energized or the EDECU hot start prevention is activated.
The external fuel tanks are ______ and _______ hardened.
crashworthy and ballistically
What is the capacity of the external fuel tank?
113 or 120 gallons
What two sensors does the external fuel tank have?
the low-level thermistor sensor and an overflow thermistor sensor if there is fuel in the external tank vent line
What is the rate at which fuel is dumped?
minimum of 800lbs/min.
How do you dump fuel from the aux tanks?
TRANSFER and MANUAL OVRD then press L / R INBD and select fuel dump
True/False: The fuel dump system is protected by weight on wheels.
FALSE.
Single-point pressure refueling has a standard psi of ____.
55psi
With power on the aircraft, what order will the tanks fill?
main, right external, left external
During gravity refueling, what order are the tanks filled?
any order
At what pressure differential will fuel flow stop during HIFR?
20psi
What will happen if your left tank vent valve is malfunctioning during HIFR?
uneven filling of the main tank may occur due to trapped air in the left fuel cell causing the fuel level to remain below the high level sensors.
the fuel flow will not be shutoff and the cell will over pressurize and possibly rupture.
If the right cell fills faster than the left, monitor and stop refueling before the right cell is full (1700lbs)
When can you initiate an unmonitored manual transfer?
3,200lbs
In order to minimize crew desensitization when fuel washes on and off the sensors, the master caution will be displayed when a fuel low condition is detected for a period greater than ________. This condition is deactivated when the condition is not detected for a period of ________.
5 seconds, 20 seconds
From which cell is fuel drawn for the APU?
the right cell
Describe the difference between [PUMP/VALVE FAIL] and [AUTO FUEL XFER FAULT].
When should you check manual fuel transfer operation?
When the main tank has depleted 300lbs
When is ALL STORES JETT inhibited for the aux tanks?
<40 gal (272 lbs.)
Use SEL JETT when the aux tank is <300 lbs. because the aux tanks only report in 50 lb. Increments
Describe the function of the FMCP mode switch ‘AUTO’
The fuel management logic is not initiated until the main tank <2640lbs.
Describe the FMCP mode switch ‘MANUAL OVRD’
Both XFER valves are open, both XFER/dump pumps are on and external fuel is transferred to the main tanks until the high level sensor is reached or the aux tanks are empty.
