AMS 365 Unit 4
What do fuel sticks do?
-Indicate fuel quantity in volume, NOT weight -Use magnet and float
What does light off, dim blue light and bright blue light mean on indications?
-Light off = Normal open position for engine fuel valves. -Dim blue light = switch is on off position and valve is closed. -Bright blue light = disagreement - ex. switch is in closed position and the valve is still open.
WHat do boost pumps provide for fuel pumping?
-Provide a positive pressure to the inlet side of the engine driven fuel pump. -Prevents EDP cavitation.
What safety precautions must be taken before a person enters the fuel cell of a large aircraft?
-Purge fuel tank -PPE -Secondary personal on standby
How can fuel be heated?
-With engine bleed air thru an air / fuel heat exchanger -Or with anti-icing additives
What is the permittivity of free space value in the capacitance formula?
0.225
What is the continuous inspection program?
for a large aircraft carrier
During T/O where does each engine draw fuel from?
from its respective wing tanks
What is capacitance?
the measure of a capacitor's ability to store an electrical charge.
What is a capacitor formed by?
two metal plates separated by a dielectric (insulating material)
What is a "D" check (HMV)?
•Most comprehensive and demanding check for an airplane. •Also known as a Heavy Maintenance Visit (HMV). •Occurs approximately every 5 - 6 years. •Man-power intensive and it can generally take up to 2 months to complete.
What is the dielectric constant of air and fuel
Air: =1 Fuel: =2
What are some disadvantages of single point/ pressure fueling?
1.More complicated to learn 2.More complicated to maintain 3.Heavier than a gravity fuel system
What two things appeared on the synoptic page?
1. Jettison time 2. Jettison system overran
What are the two categories of fuel pumps?
1. Mechanical driven 2. Electrically driven
What are the different modes of the refuel valve and what do they mean?
1. NORM: auto fueling, A/C controls fuel distribution and opening and closing of fuel valves. 2. OPEN: manual fueling / defueling; a person controls fuel distribution in A/C. 3. SHUT: manual closing of refuel valves.
What are the different modes of the mode select and what do they do?
1. OFF: Refuel system is de-energized and refuel valves are closed. 2. REFUEL: Refuel valves operate in auto or manual modes depending on the position of the refuel valve switches 3. DEFUEL: Opens defuel / transfer valve. If XFR, then the destination tank's refuel valve will have to be opened.
What are the three uses of a centrifugal booster pump that is installed in an aircraft fuel tank?
1. Positive pressure to inlet of EDP; prevents cavitation 2. Inhibits vapor lock when fuel pressure is below ambient 3. Routes the ejector pump venturi
What are some advantages of single point/ pressure fueling?
1.Ability to fuel and defuel quickly 2.Less likelihood of static electricity igniting fuel vapors 3.Closed system (no contamination) 4.Allows one or two fueling points to refill all tanks
An integral fuel tank manifold must allow for the following operations?
1.All tanks can be refueled and defueled through a single connection. 2.Any tank can supply fuel to any engine. 3.Damaged tanks can be isolated. 4.Fuel can be jettison if required
You receive a call from the inbound crew notifying you that the Crossfeed Open light stays onbright when the crossfeed selector is moved to the on position, what are the 6 possibilities for this failure?
1.Crossfeed valve actuator 2.Crossfeed valve body 3.Crossfeed valve switch 4.Wiring Probe P5-2 module to crossfeed actuator 5.Crossfeed valve indication light 6.Wiring or logic in P5-2 module
If crew reports that the number 2 fuel tank indication is too high, what are the 4 possible causes for the failure?
1.FQIS wire harness 2. Out of tank wiring from wing spar to FQIS 3. FQIS tank unit or compensator 4. Fuel quantity processor unit
What does the sensor block include?
1.Fuel Quantity Probes or Tank Units 2.Compensator (a.k.a. Densitometer)
It is reported by the crew that the Number 1 forward fuel pump has a LOW PRESSURE light illuminated (with the switch in the ON position)., what are the 5 possibilities for this failure?
1.Low pressure switch for tank No.1 fwd. boost pump 2.Tank No.1 fwd. boost pump relay 3.Tank No.1 fwd. boost pump 4.Wiring 5.Wiring or logic in P5-2 module
What are the 3 factors that can determine the amount of electricity a capacitor can store?
1. the area of its plates 2. the distance between the plates 3. the dielectric constant of the material separating the plates
What is the FIM task for the FQIS BITE procedure?
1. If ground test shows a fault message for the applicable tank, then complete a fault isolation procedure for that shown fault 2.If ground test shows pass, then there was an intermittent fault
What are the 3 non-normal conditions that relate to fuel quantity?
1. Fuel temperature 2. Low fuel 3. Fuel imbalance
What is the A320 fueling panel able to do?
1. Fueling 2. Defueling 3. Transferring fuel from one tank to another.
What is the ata code for servicing?
12
How often is the c-check?
15-21 months
What would happen to the capacitance indication on the capacitance meter as the fuel level increases? The capacitance will 1st. As the fuel level decreases the capacitance will 2nd?
1st: Increase 2nd: Decrease, because with more fuel more capacitance
How many boost pumps are used in transport aircraft per fuel tank?
2 or more
What is the ata code for fuel systems?
28
What is the ata code for water and waste systems?
38
The fuel jettison must be stopped with enough fuel for a T/O, landing, and how much cruise time?
45 minutes of cruise time
What is the ata code for nitrogen generating systems/ fuel tank inerting systems?
47
What is the ata code for time limits/ maintenance checks?
5
What is the K value for water?
80
What is CAMP?
A fleet program and encompasses the entire group of aircraft
Before entering a fuel tank it must be purged by flowing air for how long?
A minimum of 2 hours
What does the differential pressure switch detect?
A partial blockage of the filter screen and indicates an impending bypass condition exists by illuminating a Filter Bypass warning light in the cockpit
Per part 121 Air carrier inspections what are work/job cards?
Act as control documents in the continuous inspection processes
Venting fuel tanks allows for what?
Allows air to escape as the aircraft is being refueled and the incoming fuel is displacing the air in the tank
Why must fuel filters incorporate a bypass feature?
Allows the passage of fuel in the event the filter element clogs
Per FAR part 23+25, a fuel jettison system is required under what certain conditions?
As climb requirements at MTOW or if the maximum takeoff weight exceeds the maximum landing weight
Where can the refuel/defuel panel be located as an option?
At the wing leading edge
What markings must appear near the filler opening of the fuel tanks on reciprocating-engine-powered aircraft, and on a turbine-powered aircraft?
Avgas: the word avgas, minimum fuel grade Jet fuel: Max Pressure, Max suction
Why do turbojet aircraft normally have fuel temperature indicators?
Because at high altitudes in low temperatures create ice crystals
Why is FQIS more accurate?
Because it measures the mass (weight) of the fuel rather than the volume, so fuel quantity indication will not vary based on fuel temperature.
What do fuel ejectors use to draw fuel into the pump?
Bernoulli's Principle
What safety precautions should be taken before an aircraft in defueled?
Ground the truck and airplane
During the fuel jettison operation the fuel must do what when discharging?
Discharge clear of every part of the airplane
Fuel jettisoning past the limits prescribed by Federal Aviation Regulations is usually prevented by?
Dump limit valves or low- level circuits
What do flapper-type check valves do?
Ensure fuel can not flow away from the boost pumps (collector box) in any normal flight attitude
What is the primary function of the fuel ejector/pump?
Ensures fuel is always at the inlet of the boost pump, located in a fuel collector box
What is it called when large amounts of water collect on fuel filters and heat exchangers and freeze, blocking fuel flow?
Entrained water
What is Eo in the capacitor formula?
Epsilon naught
Where are the multiple electronic capacitor-type probes located for FQIS?
Extend across each tank from top to bottom
What is the purpose of a drip gage (MLI) in the fuel tank of a large aircraft?
Fuel quantity indication
Why doesn't the engines draw fuel from the center tank?
In case the fuel in the center tank is contaminated, it lessens the risk that both engines will get contaminated fuel and flame-out during T/O
What would the indication on the capacitance meter if there was an abnormal amount of water in the fuel tank when testing the probes?
High because the K of water is 80
What does the compensator (Densitometer) do?
Increases the accuracy of these systems because now changes in fuel density, due to changes in temperature, can be accounted for
What is AAIP?
Inspection programs address individual aircraft which is commonly utilized by Part 135 air charter operators with small fleets
What are the two types of fuel cells that are used in modern aircraft?
Integral and bladder
Over-flying due times or cycles of any required inspection is what?
Is a direct violation of FAA regulations and may include large monetary fines and disciplinary action
Why are job/work/task cards issued?
Issued for all aspects of CAMP inspections and are used to organize inspection instructions and account for the specific steps involved
What is the main advantage of an integral fuel tank?
It is less weight
What does turbine fuel do because it is more viscous?
It tends to hold contaminants, including water, and slows their settling to the tank sumps
When each tank reaches capacity what happens?
Its respective refuel valve will automatically close
The dielectric (electrical insulator) between the plates of the capacitance probes are made out of what?
Made up of fuel and/or air. Fuel & air have different dielectric constant (K) values
On an A320 what does the center tank do?
Last tank to fill, first tank to burn
What does MCDU stand for?
Multipurpose Control and Display Unit
Per FAR 25 the A/C must be able to jettison enough fuel to reach max landing weight within how long? How about par 23?
Part 25: 15 minutes Part 23: 10 minutes
Where is the instructional card typically located for fueling?
Placed on or near the control panel, but always refer to AMM procedures as well
What does the capacitance type ac fuel quantity system provide?
Provides fuel tank low level (amperage) signals to Fuel Quantity Indication System (FQIS)
Why are we scavenging unusable fuel from the center tank?
So the PACKS, which are located just beneath most center fuselage tanks, don't heat up the little bit of fuel in the tank creating potentially explosive vapors.
What happens when the slats are extended when talking about fueling?
The center tank fuel pumps are turned off to ensure engines get fuel from the wing tanks during T/O & landing
What closes when you shut down the engines?
The engine fuel shutoff valve
Where does the APU usually get its fuel from?
The left tank
What closes when you pull the fire handles?
The spar valve and the engine fuel shutoff valve
The crew reports that the Number 1 forward fuel pump has a LOW-PRESSURE light illuminated (with the switch in the OFF position), what are the possible faults?
There is no problems, the light is expected to be on
Fuel boost/ override pumps do what in the jettison process?
They pressurize the jettison process
How must the jettison valve be designed to do what?
To allow closing of the valve during any part of the jettisoning process
Why are fuel tanks vented?
To maintain atmospheric pressure within the tanks, which is especially important during refueling and fuel burn operations.
All fuel tanks must be vented to where?
To the atmosphere
Which of the following is employed to maintain lateral stability when jettisoning fuel?
Two separate independent systems
What is the secondary function of the fuel ejector/pump?
Water scavenges ejectors, removes water at low points in each tank to prevent the formation of corrosion, microbes, and ice.
When do fuel ejectors operate?
When boost pumps are running
When do "X FEED" illuminate?
When the cross-feed valve is open and allows the flight crew to correct fuel load imbalances .
When is the capacitance type ac fuel quantity system calibrated to read zero?
When the quantity of fuel remaining in the tank is equal to unusable fuel
How does the capacitance of the probes vary?
With the amount of fuel in the tank
Is turbine fuel more viscous than avgas?
Yes
