Chapter 7 - Engine Fuel Systems section A

Question 1

What are the two types of fuel systems?

Answer 1

Gravity-feed

Pressure-feed

Question 2

What are the typical components of a gravity-feed fuel system?

Answer 2

Two fuel tanks

fuel selector valve

strainer

primer

carburetor

Question 3

What item is required for pressure-feed fuel system?

Answer 3

Auxiliary Pump

Question 4

Where can the engine fuel shutoff vlave be NOT located at?

Answer 4

On the engine side of any firewall

Question 5

The fuel flow rate of a pump-feed fuel system for each reciprocating engine must be at what percentage of the takeoff required fuel flow?

Answer 5

125%

Question 6

What expansion space must each fuel tank have for unfilled fuel?

Answer 6

2%

Question 7

The fuel filler opening of an reciprocating and turbine aircraft fuel tank must be mark as what?

Answer 7

Reciprocating aircraft -

• “AVGAS”
• minimum grade of fuel

Turbine aircraft -

• “Jet Fuel”,
• the permissible fuel designation
• maximum permissible fueling and defueling pressures

Question 8

What is the purpose of an auxiliary fuel pump?

Answer 8

To maintain positve fuel pressure on the inlet side of the engine-driven fuel pump. It is also used to transfer fuel between tanks to redistribute fuel weight and maintain stability.

Question 9

Define Volatility.

Answer 9

The measure of Avgas’ ability to change from a liquid into a vapor.

Question 10

Define Reid Vapor Pressure.

Answer 10

The amount of pressure needed to prevent Avgas from changing from a liquid to a vapor.

Question 11

What is the vapor pressure of 100LL fuel?

Answer 11

7 psi

Question 12

What is the ideal ratio for the fuel/air mixture?

Answer 12

12(air):1(fuel)

Anything more than 12, mixture becomes lean, anything less mixture becomes rich

Question 13

What is the proper way to adjust for mixture?

Answer 13

Monitor the RPM guage then idle cut off the mixture. The should be a rise of 10-25 RPM before engine dies. If there was anything more, the mixture was too rich. If there was anything less, the mixture was too lean.

Question 14

What is Fractional Distillation?

Answer 14

A seperation of mixture into it’s component parts by heating or boiling them to their boiling points at which one or more compound or fraction will vaporize, then cooling the rest to retrieve a different chemical.

Question 15

What is added to AVGAS to eliminate or reduce detonation? What does this substance do?

Answer 15

Tetraethyl Lead

It is able to retain heat energy for long periods of time without knocking

Question 16

If fuel changes it state prior to reaching the fuel control unit, what is it called?

Answer 16

Vapor lock

Question 17

Give three reasons why vapor lock might occur?

Answer 17

routing the fuel line too close to a heat source

Excessive fuel spirals

no fuel

Low fuel pressure

Question 18

What is unusable fuel?

Answer 18

fuel trapped in the system that can never be used by the f.c.u

Question 19

Define Viscosity.

Answer 19

A substance internal resistance to flow. (It’s thickness)

Question 20

Name the different ratings of fuel.

Answer 20

80/87 - Red

90/93 - Clear

100LL - Blue

100/130 - Green

115/130 - Purple

The meaning: Hectane (lean)/Iso Octane (rich)

Question 21

What formula is used to calculate horsepower?

Answer 21

PLANK

P = Internal Pressure

L = Length of stroke

A = Area of cylinders

N = number of power strokes

K = number of cylinders

ANY CHANGES affects H.P

Question 22

Avgas ratings higher than 100 is it’s what?

Answer 22

Performance

Question 23

The heat value of fuel is measured in what?

Answer 23

British Thermal Unit

(BTU)

Question 24

How much does water weigh?

Answer 24

8 pounds per gallon

Question 25

What is edge sealer used for?

Answer 25

Sealing the edges of placards

Question 26

What fuel flow rate is required for gravity feed systems?

Answer 26

150%

Question 27

What is a micron rated fuel filter?

Answer 27

A filter that only allows particles the size of a micron to filter through.

Question 28

What does it mean when a Delta-P indicator is protruding?

Answer 28

The filter is blocked

Question 29

What is the size of a micron?

Answer 29

One millionth of a meter .000039

Question 30

Name the three parts of a filter

Answer 30

Housing Element Head

Question 31

What type of valve can be found in the head of a filter?

Answer 31

Relief Valve

Question 32

Define Vapor Lock.

Answer 32

When fuel changes its state from liquid to gas prior to reaching the fuel control unit and blocks the fuel lines.

Question 33

What are the advantages of Kerosene

Answer 33

Its has a high heat content and provides lubrication

Question 34

What is the foundation of all these different types of fuels?

Answer 34

They are all hydrocarbon based.

Question 35

What system is required for an aircraft that has a designated landing weight?

Answer 35

Jettison

Question 36

Name a characteristic of a constant displacemnt pump?

Answer 36

It is able to move the same volume of fuel regardless of speed. Supplies more fluid than the system requires

Question 37

What is the weight of AVGAS vs Kerosene?

Answer 37

AVGAS = 6 pounds per gallon Kerosene = 6.5 pounds per gallon

Question 38

An altitude compensating pump relief valve is vented to the _____ to maintain sea level pressure.

Answer 38

Upper deck pressure

Question 39

How to you lower pressure if the fuel pressure is too high?

Answer 39

Relief valve

Question 40

What can be used to prevent vapor lock?

Answer 40

Putting a fire sleeve over the fuel lines

Question 41

What is the purpose of a lay line?

Answer 41

It provides a visual reference to identify whether a hose is twisted.

Question 42

Name three requirements for the Jettison System?

Answer 42

It must be free from fire hazards. It must not alter or effect the flight. It must be able to dumb fuel and save enough for the aircraft to climb from sea level to 10,000 ft at full power.

Question 43

What is stoichiometric?

Answer 43

A air/fuel ratio of 15:1 With a stoiciometric mixture, all available fuel and oxygen are used in combustion, releasing the maximum amount of heat from the fuel.

Question 44

What antimicrobial agent is used to kill microbes, fungi, and bacteria? What are two benifits of PRIST?

Answer 44

Biobore PRIST Two benifits of PRIST: Used for Anti-icing and its a antimicrobial agent.

Question 45

Define backfiring and afterfiring.

Answer 45

Backfiring - describes the fuel/air mixture burning in the induction system with a lean fuel/air mixture Afterfiring - is the burning of fuel in the exhaust system because of a rich fuel/air mixture.

Question 46

What is the process of fuel's energy transformation?

Answer 46

Chemical -\> Heat -\> Mechanical

Question 47

What fuel nozzle is required for turbine engines?

Answer 47

Duplex

Question 48

What would happen if Kerosene was added to a recipricating engine?

Answer 48

Nothing because the compression ratio of a normal recipricatng engine is not enough to compress the fuel.

Question 49

What is the purpose of a primer and what are the two types?

Answer 49

Primer - ejects raw fuel into the manifold upstream of the intake valve. It is normally used for cold weather of the first flight of the day. Two Types: * Plunger - This is a manual type and brings fuel into the cabin * Electrical - This is remotely located and draws fuel from the main fuel manifold.

Question 50

What are the two classifications of heat exchangers?

Answer 50

Liquid to Liquid Liquid to Air

Question 51

What are two functions of a P&D Valve?

Answer 51

Pressurizes the fuel manifold Delivers fuel to the nozzle

Question 52

What is the final component of the fuel system?

Answer 52

The nozzle

Question 53

List two functions of a restrictor.

Answer 53

If the diaphram becomes broken, it will limit the fuel sucked out. If the diaphram becomes broken, it will limit the air sucked in causing pump cavitation

Question 54

What are the two classifications of pumps

Answer 54

Constant Variable

Question 55

What does "Delta P" mean on a filter?

Answer 55

It indicates if there is a change in pressure

Question 56

Why would some filters be 'pleated'?

Answer 56

To get more surface area for cleaning

Question 57

What two places does the relief valve return fuel?

Answer 57

Back to fuel reservior Inlet side of the pump

Question 58

Which jet fuel is most common? What is it's blend?

Answer 58

Jet B (JP-4) "Raw Cut" 30% Kerosene 70% Gasoline

Question 59

What is FADEC

Answer 59

Full Authority Digital Engine Control

Question 60

Where is the fuel nozzle located at?

Answer 60

In the diffuser or inlet of combustion chamber

Question 61

2 Types of nozzles

Answer 61

Simplex Duplex

Question 62

Name the parts of a constant displacement pump

Answer 62

Gears Vanes Geo Rotors

Question 63

Diaphram engine pump is driven by what?

Answer 63

Camshaft

Question 64

Fuel screens can be found where? Name four places

Answer 64

Fuel tank outlet Boot pump inlet Inline Inlet of F.C.U