15.9 Lubricants and Fuels (Level 1, 4 Questions)

Question 1

What issue did mineral oils face with the development of gas turbine engines with higher thrust and compression ratios?

A. They caused increased engine weight.
B. They lacked stability and degraded at higher temperatures.
C. They became too viscous for operation.

Answer 1

B. They lacked stability and degraded at higher temperatures.

Question 2

Why were mineral oils deemed unsuitable for advanced gas turbine engines?

A. They increased fuel consumption.
B. They exhibited excessive volatility and thermal degradation.
C. They failed to lubricate moving parts effectively.

Answer 2

B. They exhibited excessive volatility and thermal degradation.

Question 3

What type of oil was developed to address the limitations of mineral oils in gas turbine engines?

A. Ester-based synthetic oils
B. Hydrocarbon-based oils
C. Mineral-based oils with higher viscosity

Answer 3

A. Ester-based synthetic oils

Question 4

Why are original Type II oils becoming less suitable for modern aircraft engines?

A. They have poor low-temperature performance.
B. Modern engines require oils with improved thermal stability.
C. They are incompatible with ester-based synthetic oils.

Answer 4

B. Modern engines require oils with improved thermal stability.

Question 5

What are oils with extremely improved thermal stability now generally known as?

A. Second-generation oils
B. Multi-component oils
C. Third-generation oils

Answer 5

C. Third-generation oils

Question 6

What are the main tasks of oil in modern jet engines?

A. Lubricating, cooling, cleaning, and corrosion protection
B. Igniting fuel, increasing thrust, and reducing weight
C. Enhancing fuel efficiency, cooling, and increasing thrust

Answer 6

A. Lubricating, cooling, cleaning, and corrosion protection

Question 7

Why is lubrication needed between metal surfaces that move against each other?

A. To reduce friction caused by microscopic roughness of contact surfaces
B. To increase the roughness of the surfaces
C. To make the surfaces look smooth under a microscope

Answer 7

A. To reduce friction caused by microscopic roughness of contact surfaces

Question 8

What is the role of engine oil in cooling?

A. To remove heat from metal surfaces by absorbing it into the oil
B. To increase the temperature of the lubricating areas
C. To keep the oil away from metal contact surfaces

Answer 8

A. To remove heat from metal surfaces by absorbing it into the oil

Question 9

What is the cleaning function of engine oil?

A. To remove contaminants caused by gear wear or foreign particles
B. To add dust and sand into the engine system
C. To create abrasions on bearings and gears

Answer 9

A. To remove contaminants caused by gear wear or foreign particles

Question 10

What is the cleaning function of engine oil?

A. To remove contaminants caused by gear wear or foreign particles
B. To add dust and sand into the engine system
C. To create abrasions on bearings and gears

Answer 10

A. To remove contaminants caused by gear wear or foreign particles

Question 11

What is the role of engine oil in corrosion protection?

A. To prevent corrosion on metal surfaces
B. To promote corrosion on metal parts
C. To clean dirt without protecting metal surfaces

Answer 11

A. To prevent corrosion on metal surfaces

Question 12

What are the two main groups of engine oils?

A. Synthetic oils and vegetable oils
B. Synthetic oils and mineral oils
C. Mineral oils and animal oils

Answer 12

B. Synthetic oils and mineral oils

Question 13

How many types of synthetic oils are there?

A. Two
B. Three
C. Four

Answer 13

B. Three

Question 14

What is one disadvantage of synthetic oils?

A. Poor thermal stability
B. High price
C. Low pressure resistance

Answer 14

B. High price

Question 15

What is an advantage of synthetic oils compared to mineral oils?

A. They are less expensive
B. They have better viscosity, thermal stability, and high-pressure resistance
C. They have lower thermal stability

Answer 15

B. They have better viscosity, thermal stability, and high-pressure resistance

Question 16

What type of synthetic oil is mostly used on modern gas turbine engines?
A) Type 1
B) Type 2
C) Type 3

Answer 16

B) Type 2

Question 17

Which synthetic oil type has higher thermal stability and viscosity at high temperatures and is used on special aircraft like the Eurofighter?
A) Type 1
B) Type 2
C) Type 3

Answer 17

C) Type 3

Question 18

Which synthetic oil type is a first-generation synthetic oil now only used on some older gas turbine engines?
A) Type 1
B) Type 2
C) Type 3

Answer 18

A) Type 1

Question 19

What does a high viscosity index in engine oil indicate?

A) The oil’s viscosity changes a lot with temperature
B) The oil’s viscosity is least affected by temperature changes
C) The oil freezes quickly at low temperatures

Answer 19

B) The oil’s viscosity is least affected by temperature changes

• A higher number indicates a viscosity least affected by a change in temperature.

Question 20

What does the viscosity of engine oil represent?

A) Its ability to resist oxidation
B) Its internal resistance to deformation
C) Its tendency to foam

Answer 20

B) Its internal resistance to deformation

Question 21

Which is considered the most important characteristic of engine oil?

A) Flash point
B) Viscosity
C) Pour point

Answer 21

B) Viscosity

Question 22

How does the viscosity of engine oil change with temperature?

A) It is high at high temperatures and low at low temperatures.
B) It remains constant regardless of temperature.
C) It is high at low temperatures and low at high temperatures.

Answer 22

C) It is high at low temperatures and low at high temperatures.

Question 23

What is the pour point of Type 2 oils for jet engines?

A) -47 °C
B) -57 °C
C) -67 °C

Answer 23

B) -57 °C

Question 24

What is the pour point of oil?

A) The temperature at which oil starts to evaporate.
B) The lowest temperature at which oil will visibly move in a 31.75 mm test tube held horizontally for 5 seconds.
C) The temperature at which oil reaches its maximum viscosity.

Answer 24

B) The lowest temperature at which oil will visibly move in a 31.75 mm test tube held horizontally for 5 seconds.

Question 25

What is the flash point of oil? A) The lowest temperature the oil will give off enough vapour to flash when a flame is applied. B) The temperature at which oil starts to evaporate. C) The temperature at which oil becomes thick and stops flowing.

Answer 25

A) The lowest temperature the oil will give off enough vapour to flash when a flame is applied.

Question 26

What is the flash point of Type 2 oils? A) Higher than 250 °C B) Exactly 250 °C C) Lower than 250 °C

Answer 26

A) Higher than 250 °C

Question 27

What is the importance of the pressure resistance capability of engine oil? A) It helps the oil flow at low temperatures. B) It ensures the oil film resists loads and prevents contact between moving surfaces. C) It determines the oil's flash point.

Answer 27

B) It ensures the oil film resists loads and prevents contact between moving surfaces.

Question 28

Why is oxidation resistance important in engine oil? A) It prevents the oil from becoming thinner at high temperatures. B) It increases the durability of the oil by preventing it from thickening due to reaction with oxygen. C) It helps the oil cool the engine more effectively.

Answer 28

B) It increases the durability of the oil by preventing it from thickening due to reaction with oxygen.

Question 29

What problems can foaming cause in engine oil? A) Improved lubrication and cooling B) Excessive oxidation, cavitation, reduced lubrication, and potential system failure C) Increased oil pressure and viscosity

Answer 29

B) Excessive oxidation, cavitation, reduced lubrication, and potential system failure

Question 30

What is foam in oil-lubricated components? A) A collection of small air bubbles on or near the surface of the oil B) A type of oil additive that improves lubrication C) A solid contaminant found in oil

Answer 30

A) A collection of small air bubbles on or near the surface of the oil

Question 31

What does thermal stability of engine oil mean? A) The oil’s resistance to breaking down at high temperatures B) The oil’s ability to flow at low temperatures C) The oil’s color when heated

Answer 31

A) The oil’s resistance to breaking down at high temperatures

Question 32

When does the decomposition of engine oil molecules usually occur? A) At very low temperatures B) At very high temperatures, above normal engine operating temperatures C) At room temperature

Answer 32

B) At very high temperatures, above normal engine operating temperatures

Question 33

What is the term for the separation of oil from water? A) Emulsification B) Demulsibility C) Oxidation

Answer 33

B) Demulsibility

Question 34

What is demulsibility in engine oils? A) The ability of oil to mix completely with water B) The ability of oil to separate from water C) The ability of oil to resist oxidation

Answer 34

B) The ability of oil to separate from water

Question 35

What does volatility of engine oil refer to? A) How easily the oil changes from liquid to vapor B) The oil’s resistance to oxidation C) The oil’s ability to separate from water

Answer 35

A) How easily the oil changes from liquid to vapor

Question 36

What does acidity measure in engine oil? a) The oil’s viscosity at high temperature b) The corrosive tendencies of the oil c) The oil’s resistance to oxidation

Answer 36

b) The corrosive tendencies of the oil

Question 37

What is the pH value of base oils before additives are added? a) 7 (neutral) b) 3 (acidic) c) 10 (alkaline)

Answer 37

a) 7 (neutral)

Question 38

Why do additives in lubricating oils tend to be slightly acidic? a) To improve wear and corrosion protection b) To increase oil volatility c) To raise the oil’s pour point

Answer 38

a) To improve wear and corrosion protection

Question 39

What metal is particularly vulnerable to corrosion from acidic oil? a) Aluminum b) Copper c) Titanium

Answer 39

b) Copper

Question 40

What is the purpose of chemical additives in engine oil? a) To reduce engine power b) To improve oil performance and add new properties c) To increase oil consumption

Answer 40

b) To improve oil performance and add new properties

Question 41

What are the two most common types of kerosene fuel used in commercial gas turbine engines? a) Diesel and gasoline b) Jet A1 and Jet A c) Jet B and JP-8

Answer 41

b) Jet A1 and Jet A

Question 42

What is the approximate percentage composition of hydrogen and carbon in typical aviation fuel? a) 50% hydrogen, 50% carbon b) 16% hydrogen, 84% carbon c) 84% hydrogen, 16% carbon

Answer 42

b) 16% hydrogen, 84% carbon

Question 43

What is the most commonly used jet fuel in Europe, and what is its American name? a) Jet A, JP 1 b) Jet A1, JP 1A c) JP 1, Jet A1

Answer 43

b) Jet A1, JP 1A

Question 44

What is the most commonly used jet fuel type in America, and what is it called in the USA? a) Jet A, JP 1 b) Jet A1, JP 1A c) JP 1A, Jet A1

Answer 44

a) Jet A, JP 1

Question 45

Why is Jet B fuel mainly used in Canada instead of Jet A1? a) It has better cold weather performance but is more flammable b) It is cheaper to produce and has lower emissions c) It has a longer shelf life and is less flammable

Answer 45

a) It has better cold weather performance but is more flammable

Question 46

Which type of jet fuel is commonly used by the military? a) Jet A1 b) JP 5 c) Jet B

Answer 46

b) JP 5

Question 47

Why is it important to record the type of fuel used when refuelling an aircraft? a) Because each fuel type has different handling and operating characteristics b) Because fuel prices vary depending on the type c) Because it affects the color of the aircraft

Answer 47

a) Because each fuel type has different handling and operating characteristics

Question 48

What is the NATO code for JP-5 fuel and what is its other name? a) F-44, AVCAT (Aviation Carrier Turbine) b) F-35, Jet A1 c) F-22, Jet B

Answer 48

a) F-44, AVCAT (Aviation Carrier Turbine)

Question 49

What are the main requirements of turbine engine fuels? a) Low freezing point and a flash point low enough for ignition but high enough for safe handling b) High freezing point and low flash point for easy combustion c) High viscosity and high freezing point

Answer 49

a) Low freezing point and a flash point low enough for ignition but high enough for safe handling

Question 50

What should the appearance of aviation fuel be at normal ambient temperature? a) Cloudy and contains solid particles b) Clear, bright, and free from solid matter and undissolved water c) Opaque with some suspended water

Answer 50

b) Clear, bright, and free from solid matter and undissolved water

Question 51

What factors influence the volatility of aviation fuel and why is volatility important? a) Density at 15 °C, flash point, initial boiling point, and recovery temperature; volatility affects engine start and fuel evaporation b) Color, viscosity, and freezing point; volatility affects fuel storage life c) Acidity, sulfur content, and water presence; volatility affects fuel contamination

Answer 51

a) Density at 15 °C, flash point, initial boiling point, and recovery temperature; volatility affects engine start and fuel evaporation

Question 52

What does fluidity in aviation fuel refer to, and what are its key parameters? a) Maximum freezing point temperature and maximum viscosity at -20 °C; it affects fuel flow and crystallization b) Flash point and boiling point; it affects fuel ignition c) Density and color; it affects fuel handling safety

Answer 52

a) Maximum freezing point temperature and maximum viscosity at -20 °C; it affects fuel flow and crystallization

Question 53

What is the minimum calorific value of aviation fuel? A) 18,400 J/g. B) 42,800 J/g. C) 36,000 J/g.

Answer 53

B) 42,800 J/g.

Question 54

How should aviation fuel react with metals, and why does it matter? a) Reacts easily with copper; helps in fuel breakdown. b) Minimal reaction with copper and silver; protects the fuel system. c) No reaction with any metal; ensures no system issues.

Answer 54

b) Minimal reaction with copper and silver; protects the fuel system.

Question 55

Why is maximum thermal stability important for aviation fuel? a) Prevents fuel from freezing in extreme cold. b) Reduces deposit formation at high temperatures; ensures engine efficiency. c) Increases fuel density; improves energy output.

Answer 55

b) Reduces deposit formation at high temperatures; ensures engine efficiency.

Question 56

Why is it important to limit contaminants like copper, gum, and water in aviation fuel? a) Ensures fuel burns more brightly during combustion. b) Prevents engine wear, corrosion, and operational issues. c) Helps the fuel flow faster through the system.

Answer 56

b) Prevents engine wear, corrosion, and operational issues.

Question 57

Why is electrical conductivity important in aviation fuel? a) Prevents fuel from freezing during high-altitude flights. b) Reduces the risk of static electricity buildup during fuel handling. c) Improves the fuel's combustibility for better engine performance.

Answer 57

b) Reduces the risk of static electricity buildup during fuel handling.

Question 58

What is the density of Jet A1 and Jet A fuel at 15°C? a) 0.75 kg/ltr b) 0.81 kg/ltr c) 0.90 kg/ltr

Answer 58

b) 0.81 kg/ltr

Question 59

What are the main requirements for turbine engine fuel? a) High freezing point, high flash point, and low availability b) Low freezing point, appropriate flash point, low vaporization at altitude, and good lubrication c) High tendency to carry water, low volatility, and limited availability

Answer 59

b) Low freezing point, appropriate flash point, low vaporization at altitude, and good lubrication

Question 60

How can dirt and water contamination in jet fuel be managed? a) Dirt can be removed by filters, but some water will always be present b) Both dirt and water can be completely removed by filters c) Water is filtered out easily, but dirt remains in the fuel

Answer 60

a) Dirt can be removed by filters, but some water will always be present

Question 61

In what two forms can water be found in jet fuel? a) Dissolved in the fuel (invisible) or suspended as droplets (visible) b) Frozen in the fuel or evaporated as vapor c) Mixed with dirt particles or dissolved in the fuel

Answer 61

a) Dissolved in the fuel (invisible) or suspended as droplets (visible)

Question 62

Why must water be removed periodically from aircraft fuel tanks? a) Because it causes fuel to evaporate too quickly b) Because it can cause ice build-up, corrosion, and engine problems c) Because it makes the fuel heavier and harder to pump

Answer 62

b) Because it can cause ice build-up, corrosion, and engine problems

Question 63

What is another serious problem caused by water in fuel? a) It increases fuel evaporation b) It supports microbial growth in the tanks c) It improves fuel combustion efficiency

Answer 63

b) It supports microbial growth in the tanks

Question 64

What are aviation fuel additives, and how much are they usually added? a) Large amounts of compounds added to improve fuel color b) Small amounts of compounds added to provide special or improved qualities, measured in parts per million (ppm) c) Water mixed with fuel to reduce freezing point

Answer 64

b) Small amounts of compounds added to provide special or improved qualities, measured in parts per million (ppm)

Question 65

What are fuel anti-ice additives like Prist®, which contain diethylene glycol, used for? a) To improve fuel combustion efficiency b) To prevent ice formation in fuel systems c) To increase the energy content of the fuel

Answer 65

b) To prevent ice formation in fuel systems

Question 66

What problem do anti-microbial additives in jet fuel mainly address? a) Preventing ice formation in fuel tanks b) Inhibiting bacterial growth caused by water in fuel c) Reducing solid particle contamination in fuel

Answer 66

b) Inhibiting bacterial growth caused by water in fuel

Question 67

What are three common types of additives used in aviation fuel? a) Anti-oxidants, static dissipator additives, corrosion inhibitors b) Anti-freeze, lubricants, foam suppressors c) Detergents, dyes, viscosity enhancers

Answer 67

a) Anti-oxidants, static dissipator additives, corrosion inhibitors

Question 68

What do static dissipator additives do in aviation fuel? a) Increase fuel volatility b) Reduce static electricity hazards c) Improve fuel color and clarity

Answer 68

b) Reduce static electricity hazards

Question 69

What is the purpose of corrosion inhibitors in aviation fuel? a) To prevent the fuel from freezing b) To protect metal parts in fuel systems from corrosion c) To increase the fuel’s energy content

Answer 69

b) To protect metal parts in fuel systems from corrosion

Question 70

What do metal de-activators do in aviation fuel? a) Increase the fuel’s freezing point b) Reduce the effect of metals like copper on fuel oxidation c) Help the fuel flow better at low temperatures

Answer 70

b) Reduce the effect of metals like copper on fuel oxidation

Question 71

What can happen if there is inadequate ventilation when working with synthetic engine oils, especially if the oil is hot or burning? a) Improved air quality and alertness b) Respiratory irritation, nausea, dizziness, or unconsciousness c) No effect at all

Answer 71

b) Respiratory irritation, nausea, dizziness, or unconsciousness

Question 72

What can happen if synthetic engine oil gets in the eyes or is swallowed? a) Causes eye discomfort and irritation; toxic and damages internal organs if swallowed b) Has no effect on eyes; helps digestion if swallowed c) Causes temporary blindness; harmless if swallowed

Answer 72

a) Causes eye discomfort and irritation; toxic and damages internal organs if swallowed

Question 73

What skin problems can synthetic oils cause with prolonged exposure? a) No effect on the skin b) Causes irritation and can lead to dermatitis over time c) Makes skin stronger and healthier

Answer 73

b) Causes irritation and can lead to dermatitis over time

Question 74

What additional dangers does hot or pressurized oil pose? a) Hot oil can cause burns, and pressurized oil can be injected through the skin b) Hot oil cools the skin, and pressurized oil has no effect c) Oil improves skin health and cleans surfaces

Answer 74

a) Hot oil can cause burns, and pressurized oil can be injected through the skin

Question 75

What safety measures should be taken when working with engine oils? a) Use gloves, goggles, and protective clothing; wash skin with soap and water if oil spills b) Ignore spills on skin; only wash if discomfort occurs c) Use only water to clean oil spills and keep wearing contaminated clothes

Answer 75

a) Use gloves, goggles, and protective clothing; wash skin with soap and water if oil spills

Question 76

What should be done if someone is exposed to engine oil fumes in a confined space? a) Remove the person to fresh air and seek medical attention if symptoms persist b) Keep the person in the same area until symptoms go away c) Give the person water and let them rest without moving them

Answer 76

a) Remove the person to fresh air and seek medical attention if symptoms persist

Question 77

What is the best way to avoid burns from hot engine oil during maintenance? a) Remove the oil filler cap immediately after engine shutdown b) Allow the engine and oil to cool before working and wait the prescribed time before removing the filler cap c) Wear gloves only, no need to wait before removing the filler cap

Answer 77

b) Allow the engine and oil to cool before working and wait the prescribed time before removing the filler cap

Question 78

What is the biggest fire risk related to turbine engine fuels? a) Low temperature fuel leaks b) High pressure fuel leaks causing vapour build-up c) Small fuel spills that evaporate quickly

Answer 78

b) High pressure fuel leaks causing vapour build-up

Question 79

What should be done before removing major fuel components like fuel control units or fuel pumps? a) Make sure the fuel supply is isolated to avoid large spills b) Open all fuel valves to drain the system quickly c) Remove components without precautions, then clean up spills later

Answer 79

a) Make sure the fuel supply is isolated to avoid large spills

Question 80

Why must remaining fuel be drained into a suitable container after isolating the fuel supply? a) To reuse the fuel immediately b) To safely dispose of the fuel and prevent fumes hazards c) To mix it with oil for engine use

Answer 80

b) To safely dispose of the fuel and prevent fumes hazards