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2a353 Volume 3 CH 2
USAF Tactical Aircraft Maintenance CDC Questions 2016
Question | Answer |
---|---|
What is usually found at the lowest point of a fuel tank? | A sump and a drain |
What is installed in fighter aircraft fuel tanks that prevent fuel sloshing and reduce the potential for fuel ignition or explosion if the aircraft is hit by enemy fire? | Foam blocks |
Which fuel tank type is made of a rubber or nylon material and conforms to the shape of the vacant cavity within the fuselage where it sits? | Bladder-type |
Which type of fuel tank is not removable and is not self-sealing? | Integral |
What is the primary purpose of a centrifugal pump? | Pressurize the fuel manifold |
What distinct advantage do centrifugal-type pumps have over other types? | They tend to run cooler because there is no contact between the rotating impeller and the stationary housing of the pump body |
Why must the centrifugal type pump be installed at a location where fuel will flow to the pumps inlet? | because the centrifugal type pump is not self priming |
How are centrifugal pumps driven? | hydraulic power or electricity |
Which pump consists of an electric motor and shaft with circular vanes at the end? | Rotary vane type pumps |
When would a rotor vane type pump most likely be used? | Scavenging operations |
What principle applies to the operation of an ejector pump? | Venturi |
What is the function of the rotor in an air-refueling pump? | To remove fuel vapors caused by the centrifugal force of the impeller |
List 2 types of check valves | Flapper and pressure loading |
What is the purpose of the small drilled hole in the center of the flapper? | Allows some fuel to return from other parts of the system to lubricate a dry pump |
How are pressure loaded check valves opened? | By pump pressure only |
Why are shutoff valves installed in a manifold? | To control the flow of fuel or air through a manifold or into a tank |
What is an advantage of the sliding gate shutoff valve? | It has the advantage of being able to control a large flow of fuel |
What components make up a rotary plug shutoff valve? | Valve body and the motor and rotor plug |
What type of seal is used between the disc and the valve body of a disc type shutoff valve? | O-ring |
What is the purpose of a fuel level control valve? | Provides for the automatic control of the fuel level during the filling of a tank |
Piston type fuel level control valves operate on what principle? | Hydromechanical |
How is the diaphragm type valve controlled? | Electrically |
What controls the operation of the fuel control valve in a combination fuel control valve and pilot valve? | The pilot valve |
What condition may cause a temporary malfunction of a vent float valve? | Frozen condensation within the valve |
What is the definition of a switch? | A component used to open or close an electrical circuit or to select paths through a circuit |
List three types of fuel controlled switches | Pressure, float, and fue flow indicator |
How does a pressure switch work to indicate fuel pressure? | If there is sufficient fuel pressure in the manifold, the diaphragm actuates the micro switch, which completes the electrical circuit across the terminal and illuminates a pressure indicator light to indicate fuel pressure |
How are float switches actuated? | By fuel level |
What switch indicates a flow or no flow condition? | Fuel flow indicating switch |
List two types of fuel quantity indicating switches | The DC liquid level and capacitance type |
What type of fuel quantity indicating system uses the potentiometer wiper mechanism? | The DC liquid level type |
The capacitance type fuel indicating system shows how much fuel is in a tank, using what form of measurement? | Pounds of fuel |
What component controls the amount of pressure entering a fuel tank? | Air pressure regulator |
IF the air pressure regulator fails, what unit will relieve the excess pressure? | The pressure/vacuum relief valve |
What item of a disconnect coupling prevents fuel leakage from an installed external tank? | An O-ring |
What is the purpose of the aircraft fuel system? | Stores fuel and delivers the proper amount of clean fuel at the right pressure to meet the demands of the engine |
What are the four components of the engine feed system? | Pumps, check valves, shutoff valves, and thermal relief valves |
If a pump fails to operate, what component prevents the reverse from of fuel through the pump? | check valve |
What controls all shutoff valves in an engine feed system? | Throttles |
What is the purpose of thermal relief valves? | To relieve pressure from heat expanded fuel |
What is the purpose of the crossed system? | To ensure fuel is supplied to the engines at all times |
What are the three methods used to transfer fuel? | Pump, air pressure, and gravity flow |
What component controls feel level in the receiving tank during transfer? | Fuel level control valve |
How is a fuel control valve controlled? | Either by the solenoid or the pilot float |
What components are required during gravity transfer of fuel? | Shutoff valve and float valve |
Where are vent ports located? | Top of the fuel tank |
Describe the purpose of the fuel pressurization system | The system is designed to maintain air pressure in the tanks to minimize fuel boiling and, in some cases, to transfer fuel |
What system is used to remove residual fuel from a manifold? | Scavenge |
Define fueling | The filling of a tank or tanks with fuel from an external source |
What is the most common method used to refuel an aircraft? | Single-point |
During refueling, when all tanks are filled, what happens to the fuel pressure? | It increases |
What is the fuel servicing safety zone? | It is the area within 50 feet of a pressurized fuel carrying servicing component; and 25 feet around the aircraft fuel vent outlets |
What grounding procedures must be followed to properly ground the fuel truck and the aircraft during defueling? | The aircraft and fuel tank must be bonded together and connected to a low resistance ground |
Name 2 advantages of having aerial refueling capabilities | Greatly extends the range of the aircraft and permits takeoffs with much greater loads than would otherwise possible |
How is the aerial refueling receptacle operated and controlled? | Operated hydraulically and controlled electrically |
Name the principal contaminants that reduce the quality of fuel | Water, foreign particles, microbial growth, and sediment |
List some of the common types of foreign particles that can show up in fuel | Rust, sand, dust, aluminum and magnesium compounds, brass shavings and rubber |
Which color of rust indicates magnetic particles? | Black |
Sediment in fuel appears in what forms? | Dust, powder, fibrous material, grains, flakes or stain. |
What are the 2 categories of sediments? | Coarse and fine |
Define fine sediment | Particles smaller than 10 microns |
Why is classification of fuel leaks necessary? | To differentiate between those leaks that constitute a flight safety hazard and require repair before flight, and those that do not require immediate repair |
What must you use to wipe down a fuel leak? | Wipe the area dry with a clean, static free, absorbent cloth to assist the drying process |
How many leak category are there and what are they? | 4; Class A,B,C,D |
When in doubt about which class a fuel leak is, what should you do? | Classify it to the next highest category |
What are the 5 leak locations identified for fuel leak evaluation purposes? | External, Internal vented, internal non-vented, electrical conduit, and external mounted components |
What is determined when crossing the leak category with the leak location? | Condition/action |
In addition to AFTO form 781A or 781K, what form must you document fuel leaks if automated data systems are not available? | AFTO Form 427, Aircraft Integral Fuel Tank Repair Historical Record |