Chapter 5- Induction Systems

Question 1

The typical induction system on a normally aspirated engine consists of four major components. What are they?

Answer 1

1. Air Intake
2. Induction air filter
3. Fuel metering system
4. Induction manifold

Question 2

Name three types of filters used to clean incoming air.

Answer 2

1. Paper Type
2. Flock Type
3. Polyurethane Foam

Question 3

What are the three types of inducton system icing?

Answer 3

Fuel Evaporation Ice

Throttle Ice

Impact Ice

Question 4

What is Fuel Evaporation Ice?

What are the optimum weather conditions for carburetor ice to exist?

Answer 4

Also known as Carburetor Ice

In a carburetor, as fuel is released into the airstream, it turns into a vapor and absorbs heat from the surrounding air. This can cause a drop in air temperature and in some cases, this loss of heat is enough to cause the moisture in the air to condense and freeze.

Optimum weather conditions for carburetor ice to exist when the outside air temperature is between 30 and 40 degrees F and the relative humidity is above 60%

Question 5

What is Throttle Ice?

Answer 5

Throttle ice forms on the downstream side of a throttle, or butterfly valve, when it is ina partially closed position. Air flowing across and around the throttle valve creates an area of low pressure on the down-stream side. This has a cooling effect on the fuel/air mixtur, which can cause moisture to accumulate and freeze on the downstream side of the butterfly valve.

Question 6

What is Impact Ice?

Answer 6

Impact ice is caused by visible moisture striking an aircraft and then freezing. The air intake and air filter are the areas most susceptible to impact icing.

Question 7

What is the first indication of icing within the induction system is what?

Answer 7

Decrease in engine power

Question 8

What are the disadvantages of Carb Ice?

Answer 8

1. Excessive use increases the chance of dirt and foreign material entering the engine
2. If placed in “hot” position on engine start-up, damage to a carburetor heat air box could result if the engine backfires
3. Fuel/air mixture becomes richer and causes a noticible loss in power
4. High intake air temperatures from carb heat can lead to detonation during high power settings

Question 9

What position should the carb heat be left in when starting the engine?

Answer 9

Cold position

Question 10

What are the sources for carb heat?

Answer 10

1. Air inside a heater muff surrounding a hot exhaust pipe become heated then directed to a carburetor air box
2. An carburetor air box alternate air supply that can draw air from the main intake or from inside the cowling
3. Fuel-injected engines use an alternate air door that lets warm unfiltered air flow into the induction system

Question 11

An engine-driven air pump that increases manifold pressure is called what?

Answer 11

Supercharger

Question 12

A type of supercharger that has a single gear-driven impeller that increases the power produced by an engine at all altitudes is called what?

Answer 12

Single stage, single-speed supercharger

Question 13

A single impeller that can be operated at two speeds is called what?

What are the names of the two speeds?

Answer 13

Single stage, two-speed supercharger

1. Low Speeds - also known as a low blower setting has a impeller gear ratio of 8:1
2. High Speeds - alos known as a high blower setting has a impeler gear ratio of 11:1

Question 14

What powers a turbocharger?

Answer 14

Exhaust gases

Question 15

The maximum altitude that a turbocharged engine is able to produce its rated horsepower under standard atmospheric conditions is called what?

Answer 15

Critical altitude

Question 16

What is used to lube the bearing housing of a turbocharger and why?

Answer 16

The friction caused by high rotation speeds, exhaust gases flowing through the turbine, and the compression air intake all causes heat in the turbocharger so a continuous flow of engine oil must be poured through the bearing housing to cool and lubricate the bearings

Question 17

A small heat exchanger that uses outside air to cool the hot compressed air before it enters the fuel metering device is called what?

Answer 17

Intercooler

Question 18

A valve that controls the amount of exhaust gases that flow past a turbocharger turbine is called what?

Answer 18

A wastegate

Question 19

What forces are used to open and close the wastegate?

Answer 19

1. Manually through controls in the cockpit
2. Automatically through either:

• A wastegate actuator that uses a spring to hold open the wastegate and oil pressure that closes the wastegate
• Absolute Pressure Control
• Pressure-Ratio Controller

Question 20

A turbocharger system on an engine designed to maintain sea level engine performance from sea level up to their critical altitude is called what?

Answer 20

Sea level-boosted engines

Question 21

What are the four units that permit automatic control in sea level-boosted engines?

Answer 21

1. Exhaust bypass valve assembly
2. Density controller
3. Differential pressure controller
4. Turbocharger

Question 22

A spring tension pistion that closes the wategate valve with increased oil pressure and opens the wategate valve when oil pressure is released and also controlled by the density controller and differential pressure controller is called what?

Answer 22

Exhaust Bypass Valve Assembly

Question 23

What regulates the bleed oil flow from the exhaust bypass valve assembly only during full throttle operations.

Answer 23

Density Controller

Question 24

What regulates turbocharger output when sea level-boosted engines is operated at less than full throttle?

Answer 24

Differential Pressure Controller

Question 25

Which controller controls boot-strapping?

Answer 25

Differential Pressure Controller

Question 26

When a turbocharger system senses small changes in temperature or speed and continually changes the turbocharger output in attempt to establish equilibrium is called what?

Answer 26

Boot Strapping

Question 27

What type of damage can overboosting cause?

Answer 27

It can cause damage to the turbocharger, intake manifold, pistons and cylinders

Question 28

What is the term called when turbocharger controllers are not able to keep up with throttle movements which causes the manifold pressure to overshoot the desired value.

Answer 28

Overshoot

Question 29

Aside from it’s primary function, what other aditional tasks can the turbocharger do?

Answer 29

Fuel atomizing

Cabin Pressurazation

Even fuel distribution

Question 30

What is the meaning of P.R.T?

Answer 30

Power Recovery Turbine

A system which enables an engine to recover energy from the velocity of exhaust gases that would otherwise be lost.

Question 31

When an air inlet duct recovers as much as possible total pressure from the free airstream before delivering it to the compresser is known as what?

Answer 31

Ram Recovery

Question 32

What shape do subsonic inlets have?

Answer 32

A divergent shape

Pressure in increased and velocity is decreased

Question 33

What are the two types of airflow that produce thrust?

Answer 33

Primary airflow

• responsible for 20-30% thrust

Secondary Airflow

• also known as bypass airflow and used for cooling

Question 34

What are bellmouth inlets?

Answer 34

Convergent inlets designed specifically for obtaining high aerodynamic efficiency when stationary or in slow flight typically used on helicopters and slow moving aircrafts

Question 35

What engine guage should you first check when troubleshooting?

Answer 35

Oil Pressure Guage

Question 36

What two methods are used to boost manifold pressure?

Answer 36

Supercharger

Turbocharger

Question 37

What are the three carberator inherent problems?

Answer 37

Prone to icing

uneven fuel distribution

uneven atomizing