pplant finals

Question 1

The temperature of the gases within the cylinder of four stoke engine during the power stoke will:

Answer 1

Decreased

Question 2

The number of revolutions of the crankshaft required to complete a full cycle in a four stroke engine is:

Answer 2

2

Question 3

The inlet valve opens before T.D.C in the exhaust stoke to:

Answer 3

Induce a greater amount of mixture into the cylinder.

Question 4

The correct working cycle of a four-stroke engine is:

Answer 4

Compression, power, exhaust, induction.

Question 5

Valve overlap is incorporated in the valve timing of a piston engine to:

Answer 5

Improve volumetric efficiency.

Question 6

With an increase in the rotational speed of a four-stroke engine, the valve overlap:

Answer 6

Remains constant.

Question 7

In a normally aspirated engine, exhaust back pressure:

Answer 7

Decreases as an aircraft climbs and thereby reduces the rate of decline of the engine power output.

Question 8

When the spark ignites the mixture:

Answer 8

Temperature and pressure increase within the cylinder.

Question 9

If the volume of a quantity of gas is halved during compression:

Answer 9

Its pressure is approximately doubled.

Question 10

The term “Indicated Mean Effective Pressure” refer to:

Answer 10

The effective working pressure in the cylinder during the power stroke.

Question 11

The degrees of rotation to complete a full cycle on a nine-cylinder engine will be:

Answer 11

720

Question 12

The firing interval of a six cylinder horizontally opposed engine will be:

Answer 12

120

Question 13

Which of the following statements would be correct for a double banked radial engine:

Answer 13

The linear distance from T.D.C to B.D.C will accommodate two throws.

Question 14

On a four-cylinder engine with a total volume of 9,600cc, bore area of 100cm2 and a crank throw of 10cm, what would be the compression ratio be?

Answer 14

6:1

Question 15

With an increase in outside air temperature, specific fuel consumption will:

Answer 15

Increase.

Question 16

Combustion, in a four-stroke engine, theoretically occurs at:

Answer 16

A constant volume.

Question 17

During the compression stroke:

Answer 17

The mass of the mixture remains the same.

Question 18

From Top dead Centre (T.D.C) to Bottom Dead Centre (B.D.C) on the practical stoke:

Answer 18

The temperature of the gases rises for a short time then decreases.

Question 19

In a divergent duct:

Answer 19

The temperature and pressure increase, the velocity decreases.

Question 20

During the induction stroke:

Answer 20

The temperature of the gases reduces.

Question 21

Ideally, maximum pressure is attained within the cylinder:

Answer 21

When combustion is complete.

Question 22

The power output of an internal combustion engine:

Answer 22

Is proportional to the weight of the mixture induced into the cylinder.

Question 23

During the period of valve overlap:

Answer 23

The action of the exhaust gases flowing out past the exhaust valve tends to reduce the pressure in the cylinder.

Question 24

The power output of an internal combustion engine can be increased by:

Answer 24

All of the above.

Question 25

"Valve overlap" is:

Answer 25

The number of degrees of a crankshaft movement during which the inlet and exhaust valves

Question 26

The purpose of a valve spring is to:

Answer 26

Close the valve.

Question 27

Excessive blue smoke from the exhaust of an engine that has been warmed up to normal operating temperature may indicate that:

Answer 27

The piston rings are worn or stuck in their grooves.

Question 28

The camshaft of a horizontally opposed four-stroke engine rotates at:

Answer 28

Half engine speed.

Question 29

Prolonged use of low R.P.M could cause contamination of the:

Answer 29

Spark plug.

Question 30

A reduction gear is fitted:

Answer 30

Between the crankshaft and propeller

Question 31

If the starter engaged light remains on after engine start, you should:

Answer 31

Shut the engine down immediately.

Question 32

The crankshaft of an "In Line" four-cylinder aircraft engine:

Answer 32

Allows a firing order of 1-3-4-2.

Question 33

Two valve springs are fitted to each valve:

Answer 33

To reduce valve bounce.

Question 34

Excessive valve clearance:

Answer 34

Will cause the valve to open late and close early.

Question 35

Valve lead occurs when:

Answer 35

The inlet valve opens before Top Dead Centre and the exhaust valve opens before Bottom Dead Centre.

Question 36

Insufficient tappet clearance at the inlet valve would cause:

Answer 36

The valve to open early and close late.

Question 37

The length of a stroke is:

Answer 37

Equivalent to twice the crank throw.

Question 38

Tappet clearance is measured between the:

Answer 38

Valve tip and rocker pad.

Question 39

The number of revolutions required to complete the induction and compression stoke in a six cylinder four-stroke engine is:

Answer 39

2

Question 40

The purpose of a crankcase breather is to:

Answer 40

Prevent pressure building up inside the crankcase.

Question 41

Tappet clearance is provided in a piston engine to:

Answer 41

Allow for expansion of the valve gear as the engine warms up.

Question 42

Piston rings are manufactured from cast iron:

Answer 42

Because of its self-lubricating qualities.

Question 43

Brake horsepower is:

Answer 43

Useful power at the propeller.

Question 44

A method of improving "Volumetric Efficiency" is:

Answer 44

Valve overlap.

Question 45

The ratio of the power produced by an engine to the power available in the fuel is known as the:

Answer 45

Thermal efficiency.

Question 46

Specific fuel consumption (S.F.C.)

Answer 46

Is the weight of fuel used by an engine per unit horsepower per unit time.

Question 47

Exhaust valves are:

Answer 47

Sometimes have their stems partly filled with sodium to assist cooling.

Question 48

Volumetric efficiency may be defined as:

Answer 48

The ratio of the volume of the mixture drawn into the cylinder during the normal engine working, to the volume of the mixture which would be required to fill the cylinder under normal temperature and pressures.

Question 49

The compression ratio of an engine may be defined as the:

Answer 49

Swept volume+ clearance volume divided by clearance volume.

Question 50

An engine has a total volume of 2,100 cm3 and a swept volume of 1,800 cm3. Its compression ratio is:

Answer 50

7:1

Question 51

The thermal efficiency of a Piston engine can be increased by:

Answer 51

Increasing the compression ratio.

Question 52

Hydraulic valve tappets are used on some engines to:

Answer 52

Eliminate constant valve adjustment and checks.

Question 53

A normally aspirated engine is one which:

Answer 53

Is not supercharged.

Question 54

The swept volume of a cylinder is:

Answer 54

The area of the piston crown X the stroke.