PHAK Chapter 7

Continuous operation of an engine depends on the simultaneous function of ___________ ____________

Such as?

auxiliary systems

- Induction

- Ignition

- Fuel

- Oil

- Cooling

- Exhaust

Nine Main System found on small airplanes

- Cooling

- Oil Systems

- Fuel

- Electrical

- Environmental Control: Pressurization and Oxygen

- Landing Gear

- Induction systems: Carburetor/ fuel injection

- Ignition

- Powerplant: Engine and Propeller

Most small airplanes are air-cooled

Explain the airflow

then what happens?

finally...

Air flows into engine compartment through openings in front of engine cowling

Baffles route this air over the engine

Air is expelled through openings in the lower, aft portion of the engine cowling

Air cooling system is less efective during ...?

high-power, low-airspeed operations

2 Important Functions of Oil Systems

- Lubrication of the engine's moving parts

- Cooling of the engine by reducing friction

- Removing heat from the cylinders

- Providing a seal between the cylinder walls and pistons

- Carrying away contaminants

2 Basic Types of Fuel Systems

- Gravity-feed

- Fuel Pump

Explain Gavity-Feed (Type of Fuel System)

Cessna 172 capability

On high wing airplanes, the fuel tanks are physically placed above the carburetor

53 gallons of usable fuel

Fuel must be available to the engine under all conditions of:

Approved flight maneuvers

Engine power

Altitude

Attitude

Fuel Pump

If the design of the airplane is such that gravity cannot be used to transfer fuel, fuel pumps are installed

T or F

aviation gasoline is different from automobile gasoline

True, obviously

(if you so much as hesitated gtf out of here)

Aviation gasoline is prefixed by

AVGAS

( Identified by octane or performance number (grade) )

( The higher the grade, the more pressure the fuel can withstand without detonating )

Since use of the correct fuel is critical, ____ are added to the fuel to help identify the _____ and ______

Since use of the correct fuel is critical, dyes are added to the fuel to help identify the type and grade

Aviation fuel weighs ?

6 lbs./gallon

what are the two forms of electricity that are required?

descibe slighlty and give exs

Direct current (DC)

- flows in one direction

(Used in our cars, Components are heavy and not very reliable)

Alternate current (AC)

- reverses its direction

( Used in our homes, Components are lightweight, simple and reliable, Preferred for aviation use)

Battery provides what?

Battery provides power for starting the engine and a limited supply of power in the event the alternator fails

The electrical system is turned on or off with a _______ ________

How are the magnetos powered?

master switch

(Turning the master switch on powers all circuits except the ignition system)

So turning the master switch off inflight will not stop the engine

Master switch is a __________ _______:

?: controls ......

?: controls ........

Master switch is a split-rocker type:

- Left: controls alternator

- Right: controls battery power

What is a bus bar used for?

A bus bar is used to connect the main electrical system to the equipment using electricity as a source of power

What are circuit breakers used for?

Circuit breakers are used to protect the equipment from electrical overload

(either manually or automatically)

An ammeter is used to .....

monitor whether the alternator/generator is producing an adequate supply of electrical power

A loadmeter reflects ...

total load placed on the electrical system

Pressurized Aircrafts

Due to the many advantages of flying at high altitudes, many airplanes are designed to operate with a pressurized cabin

In a typical pressurization system, the cabin, flight compartment and baggage compartments are incorporated into a sealed unit that is capable of containing air under a pressure higher than outside atmospheric pressure

important info

Aircraft altitude versus cabin altitude

Pressurized Airplanes have _____ ______

examples?

several issues

-Cabin pressure must be monitored

-Cabin rate of climb must be monitored

- Potential for explosive decompression

Oxygen system

__% ?

100% oxygen

2 Landing Gear Types

- Fixed

- Retractable

Define induction systems

Brings in air from the outside, mixes it with fuel, and delivers this mixture to the cylinder where combustion occurs

two types of induction systems

Carburetor system

Fuel injection system

When does carburetor icing form?

Carburetor icing forms as a direct result of activities taking place within the carburetor itself

A carburetor vaporizes fuel, mixes it with air, and delivers it to the combustion chamber

As heat is used to vaporize the fuel, the temperature of the fuel and air decreases

As this process continues, the carburetor actually gets ten to fifteen degrees colder than the outside air

The drop in temperature resulting from fuel vaporization may cause water vapor carried by the incoming air to condense

If it condenses when the carburetor temperature is below freezing, ice may form inside the carburetor

If ice builds up, it can restrict the flow of the fuel/air mixture with resultant loss of power or engine failure

Note difference between potential and possible carburetor icing based on graph

Note difference between potential and possible carburetor icing based on graph

To combat carburetor ice, engines with float-type carburetors are equipped with ???

carburetor heat systems activated by the carburetor heat knob

Preheats the air before it reaches the carburetor 

Also used to melt ice that has already formed

Use causes a decrease in engine power, sometimes up to 15%, as the heated air is less dense than the outside air

Should not be used when full power is required

Induction systems

Fuel Injection Systems

what imp about the mixture?

Meters fuel mixture either directly into the cylinders, or just ahead of the intake valve

Induction Systems: Fuel Mixture Knob

Carburetors are normally calibrated at ?

sea-level pressure for the correct fuel-to-air mixture ratio

as the plane climbs density of air entering the carburetor decreases while the density of fuel remains the same - this is bad

To maintain the correct fuel/air mixture, you must ?

how does it work?

when is it different?

lean the mixture using the fuel mixture knob

Leaning the mixture decreases fuel flow, which compensates for the decreased air density at high altitude

during descent from high altitude, the opposite is true!

- Mixture must be enriched or it may become too lean

- Lose power and overheat

- enriched mixture

- lean mixture

- too much fuel compared to air

- too little fuel compared to air

Cessna 172 Cockpit (know diagram)

Cessna 172 Cockpit (know diagram)

What important thing does the ignition system provide?

Provides the spark that ignites the fuel/air mixture

"Dual ignition" system

- Normally 2 magnetos per engine and 2 spark plugs for each cylinder

What is a magneto?

important fact?

check how?

Magneto is a self-contained, engine-driven unit that supplies electrical current to the spark plugs

Completely independent of the airplane's electrical system

Magnetos - CHECK (RPM drop should not exceed 150 RPM on either magneto or 50 RPM differential between magnetos)

Magneto operation is controlled in the cockpit by a ?

five position switch:

OFF

R - Right

L - Left

BOTH

START

Airplane's engine and propeller (_____) work together to:

- Produce thrust to propel the airplane

- Drive various systems to support airplane operation

Airplane's engine and propeller (Powerplant) work together to:

- Produce thrust to propel the airplane

- Drive various systems to support airplane operation

reliability is more important than ____________

performance

Most airplanes designed with _________

reciprocating engines

Basic principle of a reciprocating engine is ?

the conversion of chemical energy into mechanical energy

the conversion of chemical energy into mechanical energy is accomplished through ?

name all

a process known as the four-stroke operating cycle

- Intake

- Compression

- Power

- Exhaust

Powerplant

INTAKE

Piston downward

Intake valve opens

Fuel/air mixture drawn into cylinder

Powerplant

COMPRESSION

Piston moves to top of cylinder

Used to obtain much greater power output from the fuel/air mixture when it is ignited

Powerplant

POWER

Fuel/air mixture ignited

Forces piston downward

Creates power that turns the crankshaft

Powerplant

EXHAUST

Purges cylinder of burned gases

Exhaust valve opens

What is a tachometer?

A tachometer, calibrated in hundreds of RPM, is a direct indication of engine and propeller power

Other systems include?

Hydraulics

Ice control

Autopilot ("George")

Forced Induction Systems

What is the main purpose of a hydraulic systems?

is to multiply force

- All modern aircraft contain hydraulic systems to operate various components

- Similar to power steering or power brakes in an automobile

The foundation for modern hydraulic theory is Pascal's law that states pressure applied to a confined liquid is transmitted equally in all directions without loss of pressure

In an airplane, several systems are actuated by means of " __________________"

"fluids under pressure" (hydraulic)

On small airplanes: brakes, retractable landing gear and some constant speed propellers

On large airplanes: flight control surfaces, flaps, spoilers and other systems

Flight control surfaces require a redundant system

Anti-ice

Prevent the formation of ice

De-ice

Remove ice once it is formed

Forced Induction Systems

EXTRA POWER

Turbo charger uses the engine's exhaust gas as a power source

Supercharger is directly connected to the engine, via a belt