Aircraft Fuel Systems Flashcards
Fuel jettisoning is usually accomplished
through a common manifold and outlet in each wing
The primary purpose of aircraft fuel jettison system is to quickly achieve a
lower landing weight
Fuel jettison valve must be designed to allow flight personnel
to close the valve at any time and the fuel must discharge clear of the aircraft
Which of the following is employed to maintain lateral stability when jettisoning fuel?
Two separate independent systems
A fuel jettison system is required under certain conditions if the maximum takeoff weight exceeds the maximum landing weight. What regulation covers the requirements of fuel jettison?
(FAR) 14 CFR 23, 25 and CAM 4b
Fuel is moved overboard in most fuel jettison systems by
boost pumps
Fuel jettisoning past the limits prescribed by Federal Aviation Regulations is usually prevented by
dump limit valves or a low-level circuit
Which procedure must be followed when defuelling aircraft with sweptback wings?
Defuel outboard wing tanks first
Normal fuel crossfeed system operation in multi-engine aircraft
provides a means to maintain a balanced fuel load condition
How many vents, arranged so that they are not likely to become plugged at the same time, must be used in multi engine fuel systems?
Two
What is the primary purpose of the cross-feed system?
It allows any tank to supply fuel to any engine
Fuel system components must be bonded and grounded in order to
drain off static charges
How many engine driven fuel pumps per engine are required for engines requiring fuel pumps?
One fuel pump for each engine
A typical lathe transport aircraft fuel manifold system allows how many of the following?
1. All tanks can be serviced through a single connection
2. Any engine can be fed from any tank
3. All engines can be fed from all tanks simultaneously
4. A damaged tank can be isolated from the rest of the fuel system
1,2,3 and 4
A fuel system must be designed to prevent fuel vapor ignition caused by
lightning
What is the minimum distance allowed between a fuel tank and the fire wall separating the engine?
One-half inch
Fuel baffles are installed in tanks to prevent _____ caused by changes in attitude of the aircraft
Surging
Many fuel tanks incorporate ______ valves to prevent fuel from flowing away from the boost pump or tank outlet when the aircraft is in a high “G” maneuver.
flapper
Fuel heaters are used with systems for turbine engines to prevent ______ in the fuel from clogging system filters
ice crystals
A transducer in a fuel pressure system serves what function?
Converts fluid pressure directly through a transmitter to the indicator
The use of turbine fuels has resulted in some problems not normally associated with aviation gasoline. One of the problems is
Microbial contaminants
What is used in many aircraft to prevent bubbles in the fuel after it leaves the tank when atmospheric pressure is lower than fuel vapours pressure
Boost pumps
Which of the following precautions is most important during refuelling operations?
Fuel to be used must be appropriately identified
Before fuelling an aircraft by using the pressure fuelling method, what important precaution should be observed?
The truck pump pressure must be correct for that refuelling system
What flight safety-related advantage does a pressure fuelling system provide?
Reduces the chances for fuel contamination
Aircraft pressure fueling system instructional procedures are normally placarded on the
fuel control panel access door
Pressure fueling of aircraft is usually accomplished through
at least a single point connection
Which of the following may be used for the repair of fuel leaks on most integral fuel tanks?
Riveting and resealing
How is the outlet fuel pressure regulated on a submerged, single-speed, centrifugal-type fuel pump?
By the pumps design and internal clearance
What is one purpose of a fuel tank vent?
To maintain atmospheric pressure
When inspecting a removable rigid fuel tank for leaks, what procedure should be followed?
Pressurize the tank with air and brush with soapy water
If it necessary to enter an aircraft fuel tank, which procedure should be avoided?
Conduct the defueling and tank purging operation in an air-conditioned room
What is recommended practice for cleaning a fuel tank before welding?
Steam clean the tank interior
An aircraft integral fuel tank is
a part of the aircraft structure
Which gas is used for purging an aircraft fuel tank?
Carbon dioxide
Why is the main fuel strainer located at the lowest point in the fuel system?
It traps any small amount of water that may be present in the fuel system
The purpose of a diaphragm in a van type fuel pump is to
compensate fuel pressures to altitude changes
When moving the mixture control on a normally operating engine into the idle cutoff position, engine RPM should
slightly increase before the engine starts to die
Entrained water in aviation in aviation turbine fuel is a hazard because of its susceptibility to freezing as it passes through the filters. What are common methods of preventing this hazard?
Anti-icing fuel additives
As a general rule, which statement is true regarding fuel leaks?
Stains, seeps and heavy seeps, (in addition to running leaks) are considered flight hazards when located in unvented areas of the aircraft
The presence of fuel stains around a fuel nozzle would indicate
clogged fuel nozzle
What should be used to inert an integral fuel tank before attempting repairs
CO2
What should be used to remove flux in aluminum tank after welded repairs?
5 percent solution of nitric or sulfuric acid
What method would be used to check for internal leakage of a fuel valve without moving the valve from the aircraft?
Place the valve in the OFF position, drain the strainer bowl, and with booster pump on, watch to see if duel flows to the strainer bowl
Why are jet fuels more susceptible to water contamination that aviation gasoline?
Jet fuel has a higher viscosity than gasoline
When installing a rigid fuel line, 1/2 inch in diameter, at what intervals should the line be supported?
16 inches
The probe of a capacitance type fuel level gauge is essentially a
capacitor with fuel and air as a dielectric
Which statement concerning electronic type fuel quantity indicating system is true?
It has no moving parts in the tank
What type of remote reading fuel quantity indicating system has several probes installed in each fuel tank?
Electronic
Which aircraft fuel quantity indicating system incorporates a signal amplifier?
Electronic
A drip gauge may be used to measure
the amount of fuel in the tank
The electronic type fuel quantity indicating system consists of a bridge circuit
an amplifier, an indicator, and a tank unit
A probe or a series of probes is used in what kind of fuel quantity indicating system?
Capacitor
Why is the capacitance fluid quantity indicating system more accurate in measuring fuel level than a mechanical type?
It measures by weight instead of volume
One advantage of electrical and electronic fuel quantity indicating systems is that
several fuel tank levels can be read on one indicator
A fuel totalizer is a component which indicates the
amount of fuel in all tanks
A digital fuel totalizer automatically indicates the amount of fuel used, fuel remaining, current rate of consumption and fuel
weight aboard at takeoff
What is the dielectric (nonconducting material) in a capacitance-type fuel quantity indicating system?
Fuel and air in the tank
A capacitance-type fuel quantity indicating system measures fuel in
pounds
What are the four general type of fuel quantity gauges?
Sight glass, mechanical, electrical and electronic
How does temperature affect fuel weight?
Cold weight is heavier per gallon
One advantage of electrical and electronic fuel indicating systems is that the indicator
can be located any distance from the tanks
When fuel quantity is measured in pounds instead of gallons, the measurement will be more accurate because fuel volume
varies with temp change
An electrical type fuel quantity indicating system consists if an indicator in the cockpit and a float
in the tank that moves a connecting arm to the wiper on a variable resistor in the tank
What is the purpose of a float operated transmitter installed in a fuel tank?
It sends an electrical signal to the fuel quantity indicator
In an electronic type fuel quantity indicating system, the tank sensing unit is a
capacitor
What must each fuel quantity indicator be calibrated to read during level fight when the quantity of fuel remaining is equal to the unusable fuel supply
Zero
What unit would be adjusted to change the fuel pressure warning limits?
Pressure-sensitive mechanism
Select one means of controlling the fuel temperature on turbine powered aircraft
Engine bleed air to a heat exchanger
What is the purpose of flapper type check valves in integral fuel tanks?
To prevent fuel from flowing away from the boost pumps
What unit is generally used to actuate the fuel pressure warning system?
Pressure-sensitive mechanism
What method is used on turbine powered aircraft to determine when the condition of the fuel is approaching the danger of forming ice crystals?
Fuel temperature indicator
Which of the following would give the first positive indication that a change over from one fuel tank to another is needed?
Fuel pressure warning
A fuel pressure warning switch contacts close and warning lights is turned on when
the fuel pressure drops below the specified limits
A transmitter in a fuel pressure warning system serves what function?
Converts fluid pressure to an electrical signal
Where is fuel pressure taken for the pressure warning signal on most aircraft engines?
Fuel pressure line of the carburetor
Which of the following is necessary to effectively troubleshoot a fuel pressure warning system?
The manufacturer’s maintenance manuals
Which of the following would be most useful to locate and troubleshoot an internal fuel tank in an aircraft fuel system?
Maintenance manual diagram and descriptions
In some aircraft with several fuel tanks, the possible danger of allowing the fuel supply in one tank to become exhausted before the selector valve is switched to another tank is prevented by the installation of
a fuel pressure warning signal system
The function of a fuel heater is to
protect the engine fuel system from ice formation
- Gas turbine engine fuel systems are very susceptible to the formation of ice in the fuel filters
- A fuel heaters operates as a heat exchanger to warm the fuel
Both No.1 and No.2 are true
No. 1 A fuel heater can use engine bleed as a source of heat
No.2 A fuel pressure gauge indicates the pressure of the fuel entering the carburetor
Both No.1 and No.2 are true
A fuel pressure relief valve is required on an aircraft
Positive displacement fuel pump
The primary purpose of a fuel tank sump is to provide a
place for contaminants and water to settle, with a drain valve to remove the impurities
Why are integral tanks used in many large aircraft?
to reduce weight
When an aircraft is fueled from a fuel truck or fuel farm that has not been contaminated, daily draining
of strainers and sumps is combined with periodic filter changes and inspection to ensure fuel is contaminant free
When defueling an aircraft, which of the following must be accomplished?
Always defueled outside the hangar
Integral fuel tanks on transport aircraft are
supported by the aircraft structure
What precautions must be observed if a gravity feed fuel system is permitted to supply fuel to an engine from more than one tank at a time
The tank airspaces must be interconnected
The purpose of a baffle plate used in a fuel tank is to
resist fuel surging within the fuel tank
What markings must be placed on or near each appropriate fuel filler cover on standard category aircraft?
The word ‘Avgas’ and the minimum fuel grade
What is one disadvantage of using aromatic aviation fuels?
Deteriorates rubber parts
Fuel boost pumps are operated
to provide positive flow of fuel to the engine
Flapper valves are used in fuel tanks to
act as a check valve
Why are centrifugal type boost pumps used in fuel systems of aircraft operating at high altitude?
To supply fuel under pressure to engine-driven pumps
Why is it necessary to vent all aircraft fuel tanks?
To limit pressure differential between the tank and atmosphere
According to 14 CFR (FAR) Part 23, what minimum required must be placed at or near each appropiate fuel filler cover for reciprocating engine-powered aircrafts?
the word ‘Avgas’ and the minimum fuel grade
What angle should a fuel filler neck (gooseneck) be to ensure positive pressure?
90 degrees
The location of leaks and defects within the internal portions of the fuel system can usually be determined by
observing the pressure gauge and operating the selecting valves
What type of fuel-booster pump requires a pressure relief valve?
Sliding vane
To prevent vapor lock in fuel lines at high altitude, some aircraft are equipped with
booster pumps
Some turbine powered aircraft have fuel temperature indicator located in the cockpit to
monitor the fuel temp at high altitude flight
When inspecting a fuel system, you should check all valves located downstream of boost pumps with the pumps
operating
The type of fuel boost pump that separates air and vapour from the fuel before it enters the line to the carburetor is the
centrifugal type pump
On a large aircraft pressure refuelling system, a pressure refuelling receptacle and control panel will perit one person to
fuel or defuel any or all fuel tanks of an aircraft
When routing a fuel line between two rigidly mounted fittings the line should
have at least one bend between such fittings
Which of the following tests can determine an aviation gasoline tendency to vapor lock?
Reid vapor pressure test
Microbial growth is produced by various of micro-organisms that live and multiply in the water interfaces of jet fuels. Which of the following could result if microbial growth exists in a jet fuel tank and is not corrected?
Interference with fuel flow, interference with fuel quantity indicators and electrolytic corrosive action in a metal tank
The vapor pressure of aviation gasoline is
lower than vapor pressure of autmotive gasoline
What can be done to eliminate or minimize the microbial growth problem in an aircraft jet fuel tank
Use anti-icing and antibacterial additives
Microorganisms form a biofilm that can clog filters, corrode tank coatings and degrade the fuel. They can be controlled by somewhat with the addition of what to the fuel?
Biocides
What is the maximum vapor pressure allowable for an aircraft fuel?
7PSI
If a bladder type fuel tank is to be left empty for an extended period of time, the inside of the tank should be coated with a film of
engine oil
How may the antiknock characteristics of a fuel be improved?
by adding a knock inhibitor
