aircraft system 2nd sem midterms

What is the primary purpose of an aircraft hydraulic system?

Transmit power using pressurized liquid

Which aircraft component commonly uses hydraulic power?

Landing gear

According to Pascal’s Law, pressure applied to a confined liquid is transmitted how?

Equally in all directions

Typical operating pressure of aircraft hydraulic systems is approximately what value?

3000 psi

Hydraulic systems are effective because liquids are what?

Incompressible

What property describes a fluid’s resistance to flow?

Viscosity

What happens to viscosity when temperature decreases?

It increases

Which instrument measures viscosity?

Viscometer

What does chemical stability of hydraulic fluid refer to?

Ability to resist oxidation and deterioration

What is the flash point of a hydraulic fluid?

Temperature where vapor ignites momentarily

What is the fire point of a fluid?

Temperature where vapor continues to burn after ignition

A desirable hydraulic fluid should have what flash point?

High flash point

Which hydraulic fluid is petroleum-based and dyed red?

MIL-H-5606

Which hydraulic fluid was developed to overcome the flammability of MIL-H-5606?

MIL-H-83282

Skydrol hydraulic fluid belongs to which type?

Phosphate ester-based fluid

Phosphate ester hydraulic fluids are known for what property?

Fire resistance

What color is Hyjet hydraulic fluid typically?

Purple-blue

What is the main function of a hydraulic reservoir?

Store hydraulic fluid

What does a hydraulic pump convert?

Mechanical energy into hydraulic energy

What is the function of a hydraulic filter?

Remove contaminants from fluid

Hydraulic filters typically block particles larger than what size?

10 microns

What does a check valve allow in a hydraulic system?

Fluid flow in one direction only

What is the purpose of a shutoff valve?

Stop hydraulic fluid flow

Which valve protects the hydraulic system from excessive pressure?

Pressure relief valve

What is another name for a pressure relief valve?

Safety valve

What is the main function of a pressure regulator?

Control pump pressure output

What does a selector valve do in a hydraulic system?

Change direction of fluid flow

What does a hydraulic actuator convert hydraulic power into?

Mechanical movement

What does a hydraulic accumulator store?

Hydraulic energy

What gas is commonly used in an accumulator chamber?

Nitrogen

What is one main function of an accumulator?

Dampen pressure surges

When do accumulators assist the hydraulic pump?

When several units operate at once

How many hydraulic systems are typically found in Airbus aircraft?

Three

What are the three Airbus hydraulic systems called?

Green, Yellow, Blue

Hydraulic systems in Airbus aircraft supply power to what systems?

Flight controls, landing gear, and brakes

What device allows pressure transfer between hydraulic systems?

Power Transfer Unit

What medium is used in a pneumatic system?

Compressed air

Pneumatic systems are used for what aircraft functions?

Air conditioning, pressurization, and anti-icing

What is another term for pneumatic air in aircraft systems?

Bleed air

What is a major advantage of pneumatic systems?

Air is free and abundant

Pneumatic systems are considered safer because air is what?

Non-flammable

What is a disadvantage of pneumatic systems?

Loss of precision due to gas compressibility

What is the main source of bleed air in aircraft?

Engine compressor

Bleed air is typically taken from which compressor stages?

8th and 13th stages

What does the Auxiliary Power Unit supply in pneumatic systems?

Bleed air

What is the purpose of a pneumatic ground cart?

Supply compressed air on the ground

What is the function of a precooler in pneumatic systems?

Cool bleed air

What cooling medium is used in the precooler?

Engine fan air

What does the fan air valve control?

Airflow to the precooler

What is the function of the crossbleed valve?

Connect both pneumatic systems

What is the function of the bleed air supply duct?

Transport bleed air through the system

What is the function of a HEPA filter in aircraft?

Remove airborne contaminants

What does the Bleed Monitoring Computer control?

Pneumatic system valves

Typical pneumatic system pressure is approximately what value?

40 psi

Typical bleed air temperature range in pneumatic systems is what?

200–250°C

Exposure to hydraulic fluids may cause what skin condition?

Dermatitis

What gloves are recommended when handling hydraulic fluids?

Nitrile gloves

What PPE protects the eyes from hydraulic fluid splashes?

Safety goggles

Leak detection cameras identify leaks by detecting what?

Ultrasonic sound

Approximately how many microphones are used in a leak detection camera?

124 microphones