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47 Cards in this Set

  • Front
  • Back
What is the function of a check valve?
To allow fluid to flow in one direction only.
What is the function of a bypass valve?
when pressure on inlet side exceeds pressure on outlet side, the valve will open
What is the formula for force, area, and pressure?
What are the parts of a hydraulic system?
Selector valve
What are working hydraulic lines also known as?
Operating lines.
What is the function and purpose of an accumulator?
To hold fluid pressure for normal and emergency usage.
What is the purpose of a reservoir?
To hold fluid and allow for thermal expansion.
What are ways to prevent hydraulic contamination?
1) do not service reservoir by pouring fluid directly from can
2) use only approved type of filling unit w/3 micron filter
3) do not expose hydrulic fluid to air for long time
4) if all fluid in container is not used, discard unused portion
5) destroy container after use
6) fluid drained shall not be reused
What level of filter does support equipment use?
3 Micron.
What level of filter does an aircraft use?
5 Micron.
What is the purpose of a hydraulic pump?
To allow for a flow of fluid in a hydraulic system.
What is the significance of a variable displacement pump?
It can allow for an increase or decrease of flow.
How many types of Vickers pumps are there? Whish is variable and which is constant?
7 Piston is constant
9 Piston is variable (has a yoke)
What are the 3 parts of a filter?
Head assembly
What is the most common filter on an aircraft?
5 Micron.
What is the purpose of a pressure relief valve?
It dumps pressure to the return line.
Where is the pressure relief valve found?
thermal - located in the hydraulic system where a check valve or a selector valve prevents excessive pressure from being relieved through the main system relief. also located in a subsystem.

main system - located in pressure line after the regulator. if system has no regulator it is located after the pump.
What are the 2 parts to the valve sleeve on the pressure reducing valve?
Body, poppet valve, spring, cabe, nut.
What are the 3 modes of operation to a pressure valve?
Open, free reverse flow, closed.
What are the maintenance limitations for pressure reducing valves?
Check for leaks of hydraulic fluid.
Check for proper pressure.
What are the 2 types of accumulators?
Spherical and cylindrical.
What is the composition of the cylindrical accumulator?
Made of steel and features a chromium lining.
What separates the chambers of a cylindrical accumulator?
O-ring packings.
How do you check accumulators for leaks?
Check for leaking air using soapy water. Check for leaking fluid by looking on inside.
What is the purpose of a pressure reducing valve?
reduce pressure of the main system to a lower pressure for a subsystem.
What is the pressure used on landing gear?
3000 PSI.
What position is a 3 way 2 position valve always in?
It is always in the working position.
What is the purpose of a hydraulic actuating cylinder?
To convert hydraulic to linear motion.
What is the most common actuator?
Unbalanced, dual-acting.
What is the purpose of a hydraulic motor?
To convert hydraulic pressure to rotary motion.
How is the direction of flow controlled in a hydraulic motor?
By a selector valve.
What is the sequence of operations in a landing gear door sequence?
First the doors open, then the gear goes down.
What is the purpose of teflon rings?
They are a backup and they prevent extrusion of the main rings.
What are used to clean the pistons when they move back and forth?
Metallic wipers.
What size tubing gets a metallic tag?
4" tubing.
How are hydraulic lines sized?
Metal gets sized by O.D.
Flexible gets sized by I.D.
What kind of a repair is a permaswage repair?
what is the purpose of an independant master cylinder?
to apply a flow of fluid in the "on" position.
to relieve thermal expansion.
What is the purpose of a boosted master cylinder?
To aid the pilot in applying pressure to the brakes.
What does a power brake valve do?
Uses main system pressure to help apply braking force.
What device stops lateral movement in a disc brake?
The anvil.
What are disc brake linings made of?
Heat resistant material impregnated with brass particles.
What is the purpose of a segmented rotor brake?
To apply friction and help to stop the wheels from moving.
What are the reasons for lubricating aircraft?
rubbing, water, etc
What are 3 types of lubricants?
What are 4 solids used in lubricants?
Molybdenum Disulfide
Boron Nitride
What is the most important safety element when dealing with electrical troubleshooting?
Make sure all switches are in their corresponding positions.