- What are the three principal categories of hydraulic fluids?
Mineral (5606)
Phosphate ester (Skydrol)
Polyalphaolefin (83282)
- What is the color of mineral based hydraulic fluid?
Red
- How do you determine which type of hydraulics fluid to use in a specific system?
Aircraft maintenance manual or plate attached to reservoir
- What will happen to the seals in a vegetable bees hydraulic system if it is serviced with mineral or phosphate ester based fluids?
Seals will swell, break down, & block system
- When installing a chevron seal what must be considered?
Seal is directional & install with pressure going toward the open side of seal
- When hydraulic lines have been disconnected, what precaution should be taken to prevent contamination of the system?
Hyd. Lines & fittings should be capped or plugged immediately
- What happens to the hydraulic fluid flow if the filter element becomes clogged with foreign matter?
Bypass valve routes hydraulic fluid from inlet to outlet port
- What is a micro filter?
Filter with paper element
- Name the filters used in aircraft pneumatic systems?
Paper pleated & screen type
- Why are some hydraulic reservoirs pressurized?
Ensure positive flow to the pumps & high altitudes
- What methods are used to pressurize hydraulic reservoirs?
Variable displacement pump
Engine bleed air
Hydraulic system pressure on piston in reservoir
Aspirator or Venturi
- What are the two types of accumulator housing?
Spherical & cylinder
- Name three types of hydraulic accumulators?
Diaphragm
Bladder
Piston
- What is the purpose of a pressure relief valve in a.hydraulic system?
Limit amount of pressure within the system
- What is the purpose of an unloading valve in a hydraulic system?
Provides low pressure path from pump to reservoir when system has not flow requirements
- What is the function of a wing flaps overload valve?
Prevents structural damage to the flaps from lowering at excessive speeds
- What is the purpose of the shear-able section in a hydraulic pump?
Disconnect the pump from engine so engine can run
- What are two different types of hydraulic pumps?
Hand & power pumps
- What pump is most suitable for low pressure pneumatic systems?
Vane Type pump
- What protects a direct pressure type hydraulic pressure gauge from pressure surges?
Dampening device (small restrictor)
- What are pneumatic systems used for in aircraft?
Operate brakes
Open close doors
Starting
Pump driving
Emergency devices
- What happens to the air after a pneumatic system is operated?
Air is dumped overboard
- Why should a pneumatic system be purged periodically?
Remove contamination, moisture, or oil from components & lines
- What is the purpose or the relief valve in a pneumatic system?
Protects against over pressurization
- What is the purpose of an accumulator?
Prevent hydraulic system shock when under high load demand
- What would cause a hydraulic filter to go into full bypass mode allowing unfiltered fluid into the system?
Clogged filter
