Need to Study for Airframe

Hydraulic systems liquids are used primarily for what?

They're used primarily to transmit and distribute forces to various units to be actuated.

What are the three principal categories of hydraulic fluids?

Vegetable, mineral, and phosphate-esters.

What is the color of mineral-based hydraulic fluid?

red.

How do you determine which type of hydraulic fluid to use in a specific system?

fluid is specified in the aircraft maintenance manual or on the instruction plate attached to the reservoir

What will happen to the seals in a vegetable-based hydraulic system if it is serviced with mineral-based or phosphate ester-based fluids?

The seals will swell, break down, and block the system.

When installing a chevron seal, what must be considered?

A chevron seal is directional and must be installed with pressure going towards the open side of the seal.

When hydraulic lines have been disconnected, what precautions should be taken to prevent contamination of the system?

All hydraulic lines and fittings should be capped or plugged immediately after disconnecting.

What happens to the hydraulic fluid flow if the filter element becomes clogged with foreign matter?

bypass valve will be open and allow unfiltered fluid to circulate in the system

What is a micronic filter?

A filter with a paper element.

Name the filters used in aircraft pneumatic systems.

Paper pleated and screen type.

Why are some hydraulic reservoirs pressurized?

to ensure a positive flow of fluid to the engine-driven pump at high altitudes

What methods are used to pressurize hydraulic reservoirs?

Variable displacement hydraulic pump, engine bleed air, hydraulic system pressure, or an aspirator/venturi.

What are the two types of accumulator housings?

Spherical and cylindrical.

Name three types of hydraulic accumulators.

The diaphragm type, bladder type, and piston type.

What is the purpose of a pressure relief valve in a hydraulic system?

It is to limit the amount of pressure in the system. It is in effect a system safety valve.

What is the purpose of an unloading valve in a closed hydraulic system?

An unloading valve allow hydraulic fluid flow back to the reservoir at low pressure when the system doesn’t need full flow

What type of hydraulic system has the drive motor, hydraulic pump, and hydraulic reservoir all in one unit?

Power pack.

What is the function of a wing flap overload valve?

to prevent possible structural damage to the flaps or the flap system that might result from the flaps being lowered at excessive speeds.

What is the purpose of the shearable section in a hydraulic pump?

if pump was to fail, the shear section will disconnect the pump from the engine, allowing the engine to continue to operate.

What are the two different types of hydraulic pumps?

hand pumps and power pumps.

What pump is most suitable for low pressure pneumatic systems?

A vane type pump.

What protects a direct pressure type hydraulic pressure gauge from pressure surges?

A dampening device in the form of a very small restrictor.

What are pneumatic systems used for in aircraft?

to operate brakes, open and close doors, starting pump driving, and operating emergency devices.

What happens to the air after a pneumatic system is operated?

The air is dumped overboard.

Why should a pneumatic system be purged periodically?

To remove contamination, moisture or oil from the components and lines.

What is the purpose of a relief valve in a pneumatic system?

To relieve excess pressure that develops in the system to protects the system against over pressurization

What is the purpose of an accumulator?

An accumulator stores hydraulic pressure and reduces system shock

What will cause a hydraulic filter to go into full bypass mode, allowing unfiltered fluid into the system?

A clogged filter.

What percentage of an oil reservoir is left empty for oil expansion?

At least 10% or half a gallon.

What is the difference between an open center hydraulic system and a closed center hydraulic system?

An open center has fluid flowing continuously. A closed center system fluid flows only when a component is operated.

The production of gaseous oxygen for commercial or aircraft cylinders is often through what process?

process of liquefying air.

What is the principal control element in a cabin pressurization system?

The cabin outflow valve.

What is the purpose of the negative pressure relief valve in the pressurization system?

The negative pressure relief valve prevents outside air pressure from becoming higher than cabin pressure

What control changes the position of the outflow valve?

The pressurization controller located in the cockpit.

What are the two groups of independent cabin compressors?

positive displacement and centrifugal compressors.

What method is used by turbine powered aircraft for pressurization?

Engine bleed air

What limits the degree of cabin pressurization?

by the strength of the fuselage and the ability of the superchargers to supply enough air

Where does the warm air for cabin heating come from in most small reciprocating engine aircraft?

from the shroud around the engine muffler.

What are the three methods of supplying heat to the conditioned air when the heat compression is not sufficient for this purpose?

Fuel burning combustion heaters, electric heaters, and exhaust gas air-to-air heat exchangers.

What is the function of ventilating air in a combustion heater?

Ventilating air is used to carry the heat to the places where it is needed.

Where does the fuel used in an aircraft combustion heater come from?

The aircraft fuel tanks.

What controls the temperature in an aircraft cabin that is heated with a combustion heater?

A thermostat.

What are the sources for ventilation air in a combustion heater?

A blower for ground operation; ram air or cabin pressure in flight.

What are the components of an air cycle cooling system?

An expansion turbine, an air-to-air heat exchanger, and various valves which control air flow through the system.

What causes the temperature drop in an air cycle cooling system?

As compressed air passes through the expansion turbine, it turns the turbine and drops in pressure and temperature

What are the components in a vapor cycle cooling system?

The compressor, condenser, receiver/dryer, expansion valve, and evaporator.

How do you determine the liquid level in a vapor cycle cooling system?

observe the the sight glass: steady liquid means enough Freon; bubbles mean low Freon.

How is the vapor cycle cooling system compressor lubricated?

Specialized refrigerant oil.

What are the components of a continuous flow oxygen system?

Oxygen cylinder, regulating reducing valve, and a calibrated orifice in the mask outlet.

What must be done if an oxygen system has been depleted and not recharged within 2 hours?

It must be purged with dry nitrogen or dry air and oxygen.

What safety consideration must be observed when filling oxygen cylinders?

Oxygen cylinders should be filled in an oil-free environment. No petroleum products on clothes, hands, or hair.

What is the main chemical agent inside of an oxygen generator?

Sodium chlorate.

How are high and low pressure oxygen cylinders identified?

High pressure are green with white letters; Low pressure are painted light yellow.

What are the three ways that supplemental oxygen can be carried in an aircraft?

As liquid oxygen, a high-pressure gas, or as a chemical candle.

What is an acceptable lubricant for installing oxygen system fittings?

Teflon or water-based lubricants.

What type of grade of oxygen must be used in aircraft?

Aviators grade breathing oxygen.

What is a roots blower?

A type of engine-driven compressor.

What is a British Thermal Unit?

It is a unit of heat; the amount of heat required to raise the temperature of one pound of water by one degree F.

How does a water separator work in an air cycle air conditioning system?

It operates using centrifugal forces to spin the water out of the air.

How many people does it take to service an oxygen system?

Two. One to apply pressure and one to monitor the gauge.

Name two types of air conditioning systems.

Vapor cycle and air cycle machine.

What are the sources of ventilating air in a combustion heater?

Ram air while flying and electric blowers on the ground.

There are usually two parts to any instrument or instrument system. What are they?

One part senses the situation and the other part displays it.

What three-flight instruments are normally operated from the pitot-static system?

The air speed indicator, altimeter, and vertical speed indicator.

What instrument indications will result if the static pressure line becomes disconnected inside the cabin of a pressurized aircraft?

Altimeter and airspeed show lower than normal; VSI briefly shows descent, then returns to zero

Who is authorized to perform tests to calibrate an altimeter?

The manufacturer or a certified repair station.

What is required after replacement of components connected to the pitot-static system?

A leak test.

In wet type vacuum pumps, what are the vanes made from?

Steel.

How are vanes of a wet type pump lubricated?

by Engine oil.

What is battery capacity measured in?

Amp hours.

What is the purpose of a circuit breaker?

to protect the circuits and wires from fire by opening when an overload exists.

What are the two principles on which circuit breakers operate?

Thermal and magnetic.

What tool is used to measure the size of an unmarked electrical wire?

A wire gauge.

What are the colors of aircraft position lights and where are they mounted?

green (right wing tip), red (left wing tip), and white (rear of aircraft).

What are the factors to be considered when selecting wire size for electrical power?

power loss, voltage drop, and current carrying ability.

When is a circuit breaker or fuse designed to open the circuit?

before the conductor emits smoke.

before the wire gets hot enough to catch fire

What type of breakers are not acceptable for use in aircraft?

Auto reset breakers.

What is a slow blow fuse?

fuse allow short spikes pass but blows if the current stays high

What are the three most common faults that occur in electrical current?

open circuits, shorted circuits, and low power.

What size electrical conduit should be used for a specific cable bundle?

inside diameter at least 25% bigger than the wire bundle

What color insulator on a solderless connector is proper for a 10 gauge wire?

Yellow.

How should electrical switches typically be oriented in the on position?

Up or forward.

What should be checked before any aircraft electrical load is increased?

Wires and circuit protection to ensure the new load will not exceed limits.

What warns pilots of overheating batteries?

A thermal sensor in the battery and a light in the cockpit.

How long should bonding jumper wires be made?

as short as possible to prevent an increase in resistance.

What are the two items that wear on a starter generator?

The commutator and the brushes.

What powers the ELT?

An internal battery

What is the purpose of a static wick?

It dissipates static energy from the aircraft.

What are the two types of AC generators?

Single-phase and three-phase.

When repairing an aircraft electrical component, what references do you use?

The manufacturer's maintenance manual.

What is the preferred method of charging NI-Cad batteries?

Constant current charging.

What is the max allowable voltage drop from a generator to a bus bar?

2%.

What system components can be used for troubleshooting an aircraft electrical system?

voltmeter and ammeter.

What is the most common size of wire used on an aircraft electrical system?

22 gauge.

What is a CSD and what does it do?

constant speed drive; keeps generators spinning at a constant speed.

Name one of the most common anti-icing systems in use.

thermal, pneumatic, thermal-electric, and chemical.

Describe the operating principle of inflatable deicer boots.

Rubber inflatable boots break ice off via an alternating inflation/deflation cycle.

Why is it critical to prevent the formation of ice on wings?

Distorts wing shape, reducing lift, and adds stress/weight to the airframe.

What are two methods of inflating pneumatic deicer boots?

engine-driven air pump or bleed air from the turbine engine.

What methods are used to attach deicer boots?

bonding with cement, fairing strips and screws, or combination.