Fuel System Flashcards
What type of fuel system do we have?
crashworthy, suction-type system with a self-sealing main tank
All lines include_____ that stop fuel flow in the event of fuel system damage
self-sealing breakaway valves
What are 2 possible causes of a low pressure condition leading to #1/#2 FUEL PRESS cautions?
Either a malfunction of the engine driven boost pump or an air leak
Note: The fuel filters are not sensitive to _______, which may cause _________ in one or both engines with no associated FUEL PRESS or FUEL FILTER BYPASS caution.
water contamination, fluctuations/ surges
Placing the FUEL PUMP switch to APU BOOST ______ and _______
opens the APU shutoff valve and activates the prime boost pump
Placing the FUEL PUMP switch to FUEL PRIME ________ and ________.
opens both engine prime shutoff valves andallows individual priming of the engines with the PCL in LOCKOUT
The fuel system capacity is ________
590 usable gallons (4012 when fueled with JP-5)
The fuel cells are located________
behind the cabin in the transition section
The ___________ of the tank is self-sealing
lower one third
The main cells’ interconnect level is ______
approximately 270 to 600 pounds per side
What type of aux tank is each inboard weapons pylon configured to accept?
crashworthy, balistically hardened 120- or 113- gallon capacity external auxiliary fuel tank.
The aux tank has ___________ so that no fuel will be spilled in the event of separation of the tank
self-sealing breakaway valves
The fuel level of each aux tank is measured by______, which sends a signal to the MDs/FDs and FMCP
a single gauge probe
Each aux tank has a ________ sensor that is exposed only when the tank is ________ and then sends a signal to the ________.
low-level thermistor
empty
FMCP
Each aux tank contains an overflow thermistor sensor that sends a signal to the FMCP if fuel is sensed_________
in the external tank vent line
When fuel is sensed in the external tank vent line, a signal is sent to illuminate the _______ caution
EXT FUEL OVERFLOW
If _____ and _____ are absent, the FMCP commands automatically bypass that tank station and go to the next occupied tank station
an auxiliary tank gauge and low-level switch
A SINGLE valve and pump of the DUAL pump/valve system functions during the _____ fuel transfer mode. The valve and pump activated alternates with each activation of this mode.
automatic
When a single valve or pump fails, the _____ caution will appear, and the alternate pump or valve will supply fuel transfer capabilities
PUMP/ VALVE FAIL
The AUTO FUEL XFER FAULT indicates_________
a lack of fuel transfer from the auxiliary tanks to the main tank
AUTO FUEL XFER FAULT could be caused by________
“FBFB”
- Failed closed transfer valve
- Both transfer dump pumps inoperative
- FMCP control failure
- Blockage in the associated lined
The fuel transfer system is controlled by the _____ and consists of _______.
FMCP, two transfer/ dump pumps that provide the capability to transfer fuel from the external tanks to the main tank
When fuel transfer is manually selected, the selected external tank shutoff valve is _______ and fuel transfer occurs until the fuel level reaches the ______, at which point the _______ will shut off the pumps.
energized open
high-level shutoffs of the main tanks
flow sensor
During Fuel Transfer, indications of fuel flow are:
- FUEL MGT panel R INBD or L INBD light illuminates on the FMCP
- Tank quantity changes on the mission display fuel graphics for the respective fuel tanks.
If fuel quantity indicators on the FD or MD fuel graphic do not change during manual transfer, then:
the fuel transfer system is inoperative
CAUTION: During transfer of aux fuel, if right cell fills faster than left cell, monitor the fuel quantity gauges closely. If difference in cell quantities persists, stop transferring fuel before ____ cell is full (approximately_____ lbs)
right cell, 1700
CAUTION: Do not initiate unmonitored manual transfer to the main tank from aux tanks until main tank is below _____ pounds. During manual aux tank transfer, the _________ should prevent overflow of the main fuel tanks.
3200
main tank high-level sensor (float valves)
When main fuel tank capacity has decreased _____ pounds, check the manual fuel transfer system to ensure proper transfer. One short manual transfer will________.
300
exercise both transfer pumps and transfer valves to ensure proper operation
Note: Emergency jettison of external fuel tanks via the ALL STORE JET pushbutton is inhibited with less than ____ gallons (approximately _____ lbs) in the tank. SEL JETT must then be used. The fuel gauge for the external fuel tank reads in ____ lb increments. If the xternal fuel tank requires jettison and the fuel gauge reads ____ lbs or less, SEL JETT should be utilized.
40 gallons, 272 lbs
50 lb increments
300 lbs
Refuel sequence
Main tank, right external, left external
AUTO fuel management logic is not initiated until the main fuel tank level depletes to approximately_____
2640 lbs
Automatic fuel transfer sequence
left external, right external
L INBD FLOW and R INBD FLOW indicates______
fuel flow into OR out of the external tanks
How to manually transfer fuel
TRANSFER, MANUAL OVRD, push L INBD or R INBD
FUEL DUMP is illuminated when______
fuel flow is sensed in the dump tube
What happens when precheck A or B is selected?
power to the respective precheck valve is interrupted, fuel flow during refueling is stopped, and fuel flow on FMCP flow lights will go out
NOTE: A malfunctioning FMCP with electrical power applied can cause activation of precheck valves, preventing the ability to pressure refuel or HIFR.
How do you secure the precheck valves to allow fueling?
The FUEL MGMT circuit breakers on the COPILOT cb panel must be pulled to secure the precheck valves to allow fueling.
How is fuel quantity indicated?
A fuel probe is mounted in each cell. The tank probes are capacitance type sensors that employ fuel as a dielectric to measure the weight of the fuel in each tank.
How are the fuel quantity sensors interconnected to the primary and backup mission computers and flight displays?
Two DTC’s
The fuel low level warning system has ______. When fuel in one of the fuel cells reaches _____ pounds, the #1/#2 fuel low caution appears and the associated digital fuel readouts on the mission and flight displays turn yellow. When total fuel reaches ____ pounds, the total fuel display also turns yellow.
two separate and independent indications.
300 lbs
600 lbs
________ may cause the #1/#2 FUEL LOW cautions to illuminate and extinguish
Fuel washing on and off the sensors
Minimum dump rate of the fuel dump system
800 lbs/ minute
When fuel dump is selected, it will dump from a port in the _____ down to the _______
right fuel cell
low level sensor
How to dump fuel
TRANSFER, MAN OVRD, select the FUEL DUMP switch o the MERGENCY FUEL DUMP SWITCH panel on the lower console
WARNING: After dumping_______
check fuel readout to ensure that dumping has ceased
NOTE: Regardless of FMCP switch positions or whether external tanks are installed, selecting ______ will enable emergency dumping from the _______. FMCP switches need only be set to TRANSFER and MANUAL OVRD if pilots desire to dump fuel from the eternal tanks. With no aux tanks, you can dump from the main tank in any configuration of the FMCP including stop flow.
FUEL DUMP
Main tank
Can fuel be dumped with the helicopter on the ground
YES. The fuel dump system is not protected by the WOW switch
A pressure refueling port is provided for standard ___ psi pressure refueling on the ground with or without electrical power
55
Fuel quantity indicators are not operable without _____ and must be visually checked
ac electrical power
If a left external tank is installed and not a right one, there will be _____
a delay in filling th elef tank after the main tank is filled while the FMCP determines that there is no right tank to fill.
If fuel flow continues after a precheck valve is held in position, then:
there is a malfunction in the shutoff valves
When refueling, the high level shutoffs will close the _____ at a predetermined level of fuel
fuel/ defuel valve
Three components of the HIFR system:
- Wiggins quick-disconnect, pressure-refueling fitting
2, Pressure refueling precheck switch to allow the high level sensors to be checked from inside the aircraft - 5 element GO/ NO-GO cannister
Once a ___ psi pressure differential exists in the GO/ NO-GO cannister, the fuel flow stops
20 psi
If the helo must be refueled when the quality of fuel is in question, it should be refueled through
the HIFR fitting (removes both water and particulate matter)
If the _____ should malfunction and remain stuck in the closed position during HIFR, _____ may occur
left tank vent valve, uneven filling of the main tank cells
Interconnect opening level
600 pounds in each cell
What happens if there is trapped air in the left main cell during refueling?
After fuel has risen above the interconnect level, the left side will slow while the right side continues normally. Without fuel reaching the high-level shutoff sensor in the left cell, the right cell can reach an overpressure condition and cause possible cell rupture.
In order to minimize aircrew 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 5 seconds and will be deactivated when the condition is not detected for a period of 20 seconds.
