Flashcards in Fuel Deck (32):
Where does APU get fuel?
Right side collector tank.... Fed by by electrical pumps when engine not running. Or by primary ejector pumps when engines running.
How are engines fed fuel?
Primary ejector pumps which are driven by high pressure motive flow supplied by dedicated engine driven fuel pumps.
Purpose of AC pumps and location?
One in each tank. Provide primary engine feed in the event of ejector pump failure. And provide fuel pressure for ground and inflight start.
What are the sub tanks?
Surge tank for wing down or uncoordinated maneuvers. Collected tank.
How does collector tank work?
Located at wing root. Fuel flows from tip to root and into e collector tank. Each tank has baffle and flapper check valves that prevents fuel from draining from collector tank thus ensuring that fuel is always avail.
Each tank has vents with independent lines and vents into the surge tanks.
How many drains?
Two on each side. One in collector tank area and other near the wing stub to wing junction. At low points to ensure water can be drained.
Types of fuel indications.
Electric fuel quantity
Mechanical fuel quantity
Fuel low level indication, which is a separate probe.
Primary fuel indication?
AC capacitance type electrical fuel indicating subsystem.
Back up fuel indication?
Magnetic level indicators. Allows dispatch.
Temp required for fuel indication to show green?
Temp indicator will show in green as long as temp is above -37. Below that shows in amber or amber dashes if there is a fault.
Location of temp sensor?
Attitude that can cause starvation
15 degrees nose up or down... Uncoordinated maneuvers or negative g forces.
How many magnetic stick indicators?
Three in each tank.
How does magnetic stick work?
Twist to unlock. Each has a float. It will drop down... Use the indications on the side to refer to book to get load.
Three subsystems of fuel distribution?
What powers electric pump in an emergency?
AC pump in right tank powered by the AC ESS bus which is powered by the RAT if needed.
What is used for APU start on ground?
DC pump in right wing.
With AC pump in auto what happens if ejector pump fails?
Ejector feeds engine and AC pump will take over automatically if ejector pump fails.
What operates the fuel SOV or the engine fuel shut of valve?
The fire handle.
What is used for electrical power if APU is inop and there is no ground power?
The DC fuel pump can be sued to start the right engine.
How does cross feed work?
One tank feeds both engines or to x feed due to on engine inop.
Cross feed valve closed during normal operations.
When a side is selected for cross feed... If left tank is low... Turn switch to "low 1" and AC pump two turns on, the cross feed valve is open and AC pump two feeds engine one...... AC one will feed engine two if the other way around.
Can fuel be supplied to APU from left tank?
Yes, by selecting low 2
Start sequence for APU?
DC pump used unless AC power is available. With engine running then ejector pump feeds APU.
Where is grounding for fueling?
Right landing gear.
If over wing then grounding points under wings.
Can fueling be done without power turned on?
Yes, with power selector in battery position. Power comes from the hot batt bus.
Must have AC power and grounded... Open switch on panel..
Hboth AC pumps to on position then either one or two low position...
At desired level, put cross feed to off position.
Defueling switch to open.
Cross feed to one or two. At desired level put panel switch to closed and then cross feed off.
Can a fuel low level warning occur with adequate fuel in main tanks?
Yes, if the collector tank has low fuel. This can be caused by neg g forces, 15 degrees pitch up or down or uncoordinated maneuvers.
If this happens check the fuel indications for that side.
Fuel imbalance numbers
The limit is 794
Caution message at 800 pounds
Message indicating normal with the difference is within 100 pounds