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75 Cards in this Set
- Front
- Back
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What is the purpose of a bleed air system? |
to operate or control pneumatic systems/components |
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What are 3 sources of bleed air to operate the aircraft? |
aircraft engine ground air cart APU |
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List components of a bleed air system. |
Valves and air ducting |
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What is the purpose of a ground-air connection check valve? |
Prevents air from escaping the system |
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Why is velocity of airflow greatest at the venturi throat? |
because air pressure is higher (smaller space) |
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What function does a pressure limiter serve in a bleed air system? |
protects components from excessive air pressure |
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What factors maintain a constant pressure in a flow control valve? |
inlet temperature and pressure |
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What material is usually used for high pressure/high temperature ducting? |
stainless steel |
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To ensure a good airtight seal when installing a V-clamp, what action should you take? |
tap clamp with rawhide mallet make sure clamp is aligned correctly |
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Why should you install the bottom bolts on a bolted flange duct first? |
forms a cradle for easier installation |
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What type of lubricant can only be used on beaded duct sleeves to aid installation? |
Water |
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List 3 components that are used to compensate for thermal expansion |
Expansion joints universal joints loops |
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What must you do first to perform an ops check of the bleed air system? |
Turn on electrical system place switches to open and closed positions |
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When is a leakage test required on a bleed air system? |
After maintenance is performed on the bleed air system |
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You are ready to begin the leak check, after you check the TO for correct valve positions. What is the next step? |
Apply air pressure |
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What are the 2 most commonly used methods for detecting leaks and how do you perform them? |
Hand survey and pressure decay |
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Describe the operation of a heat exchanger |
Outside air flowing across the core cools the water the water flows into the engine to prevent overheating |
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What is the purpose of the water aspirator and regenerative heat exchanger? |
To provide additional cooling |
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How does the compressor turbine section increase operational efficiency? |
By increasing bleed air pressure before sending it to expansion turbine |
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What are 3 benefits of ceramic bearings over steel bearings? |
harder than steel can tolerate hotter temperatures much smoother |
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A cooling turbine unit had been operated for several hours without replacing the oil supply. you are inspecting the unit and notice the turbine oil is slightly darker than normal and has a few dark particles in it. What actions do you take? |
Replace turbine
rapid discoloration indicates trouble and particles indicate breaking down of internal parts |
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Explain how an electronic temperature control anti-icing system operates. |
sensor transmits signal to controller controller causes actuator to position itself based on the temp |
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Explain how ice control screen anti-icing system operates. |
Ice builds up on the screen temperature increases and melts ice |
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What happens if the condenser bag freezes or is dirty enough to prevent airflow through the bag? |
Pressure builds up and forces the relief valve open (normally held closed by spring) |
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Which components could cause a malfunction that leads to excessive moisture in the cabin eat lower altitudes? |
Bypass valve vent line aneroid switch |
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What air source is used for cabin ventilation? |
atmospheric |
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What is the purpose of the ground cooling ejector valve? |
allows bleed air to flow through the ejector pump nozzles located in the ram air outlet duct |
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What purpose does the flow limiting venturi serve? |
prevents pressure surges from reaching the turbine prevents complete pressure loss if rupture disc ruptures |
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What are the positions of the dual-temperature mixing valve butterflies when the pilot is receiving the maximum amount of cold air in the cockpit? |
Butterfly leading to cooling turbine opens Butterfly leading to hot bleed air closes |
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What component is used to start and stop the bomber ACS? |
ACS pressure regulator and shutoff valve |
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What is the purpose of the catalytic filter? |
to remove any contaminants in the air supply |
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What position does the flow control valve modulate toward when a decrease in control pressure is sensed by the flow control sensor? |
open to allow more airflow |
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What components absorb the power produced by the expansion turbine? |
compressor turbine and cooling air fan |
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What system controls bleed air temperature to 450 degrees F? |
Primary heat exchanger |
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What is the purpose of the turbine bypass valve? |
opens if air temperature at water separator becomes too cold. tries to maintain 38 degrees F |
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What is the purpose of the Air conditioning diverter valve? |
controls airflow to either the flight station and/or the cargo compartment under varying conditions |
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Why would the fan in the temperature sensor assembly not operate when the temperature control switch is in manual? |
The fan only operates in automatic mode |
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What unit is energized at the same time as the floor heat shutoff valve? |
floor heat modulating valve |
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Functions of the venturi. |
to limit the flow of bleed air |
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After the air exits the air conditioning turbine, where does it go next? |
the water seperator |
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What happens once the control rheostat is in the COLD position? |
the warm air modulator starts to open causing warm air bypass and check valve to pass hot air |
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What happens to the air the next time the pack is turned on after yo place normal reverse switch in the REVERSE position? |
the conditioned air is directed to the electronic packs first
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What components will you check first if the air conditioning system went full hot during automatic operation? |
Temp controller temp sensor control rheostat |
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You think you have defective temperature controller on an air conditioning system. What steps will you take to verify this condition? |
Turn power on aircraft and check power output of the temp controller to modulating valves |
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What bodily sensation would the pilot feel when pulling 2 positive Gs? |
Pushed down hard into seat heavy arms and legs |
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What effect do excessive Gs have on the body? |
Gray out Black out and unconsciousness Drains head of blood |
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What effect does negative G-force have on the body? |
Red out rushes blood to head |
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Explain the automatic operation of the anti-G suit system. |
when 2 or more Gs are pulled, G suit bladders inflate using bleed air |
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During take off more than 2 Gs are encountered. What happens to the anti-G suit? |
The weight moves, closing the exhaust valve and opening demand valve, inflating the suit |
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What are the 2 methods for defrosting the aircraft windshields? |
NESA windows hot air blown across window |
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A pilot moves the defog lever from the foot heat position to defog. From where does the defog source of air come? |
conditioned air, which directs the air for foot heat as well |
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A pilot's write up states the windshield was only partially cleared of fog during flight. What should you check? |
Cracked, torn, loose ducting operation of defog control valve |
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What is the function of the controller amplifier in the NESA anti-icing circuit? |
control windows heat through a bridge circuit |
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What can be checked on the individual window units in the NESA glass system? |
Resistance |
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What is the purpose of a thermal snap switch in the NESA window anti-icing circuit? |
Remove power from window 10 mins after it reaches 70 degrees |
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What position is the control valve in when upstream anti-icing air pressure is too low to provide the regulated air pressure? |
It opens fully |
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After the anti-icing air flows through the wings double skin passages, it returns to the plenum. What happens to this air next? |
Part returns to the jet pump as re-circulating air, the rest goes overboard |
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List the 3 pressurization ranges. |
Unpressurized Isobaric Differential |
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Whats the cabin altitude when the aircraft is flying at 15,000 ft in isobaric range? |
8,000 ft |
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Explain how the isobaric section of the pressure regulator keeps the aircraft unpressurized below 8,000 ft. |
When the outflow valve opens, air from the A/C system flows through them. This keeps the cabin at 8,000 ft |
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State the purpose of the dual-differential pressure regulator's changeover solenoid. |
Changes differential from 7.75 and 4.50 |
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How is the safety outflow valve operation affected if a pneumatic relay were not used? |
The outflow valves would open at different times |
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How many feet does the unpressurized range go up to when the cabin altitude selector is set at 10? |
10,000 ft |
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What is one problem with the manual control valve? |
When pressure conditions change, the pilot must readjust it manually |
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List the 3 positions of the pressure regulator test handle |
Flight differential test test only |
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What unit probably failed to operate properly if you find 2 canopy seals ruptured on an aircraft? |
the canopy seal pressure regulator |
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Which component's action does the outflow safety valve operate through? |
pneumatic relay |
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What occurs inside the cabin pressure controller once you adjust it to the predetermined altitude setting? |
cabin altitude selector coil spring, rocker arm fulcrum and isobaric aneroid work together in selecting altitude setting |
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What actions cause pressure to buildup in the lower chamber of the cabin pressure controller? |
when aircraft ascends, cabin pressure builds up in the controller chamber because the isobaric metering valve is closed |
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What can you do if the cabin pressure controller and the outflow valve does not open at 9.42 psid? |
open manual control valve to drain pressure |
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You think that the sensing line is causing the cabin to pressurize from the ground up when the altitude selector is set at 8,000 ft. What should you do next? |
Disconnect and cap the sensing line at the relays disconnect the line at the sensing cabin pressure controller |
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Where are your greatest hazards when you are pressurizing an aircraft? |
hatches windows canopies windshields |
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What will normally happen to you in a pressurized aircraft if you have congestion? |
high pressure can cause sinus cavities and ear canals to rupture |
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What is prevented from happening when you move the rate selector valve into the start position and start the tester? |
Uncontrolled pressure from being applied to the aircraft cabin |
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What should you do after applying pressurized air to the canopy seal? |
Inflate the seal to prevent leaks |
