Reciprocating Engines

Question 1

Which statement is true regarding bearings used in high-powered reciprocating aircraft engines?

Answer 1

There is less rolling friction when ball bearings are used than when roller bearings are employed.

Question 2

A condition that can occur in radial engines but is unlikely to occur in horizontally opposed engines is what?

Answer 2

Hydraulic lock.

Question 3

Which condition would be the least likely to be caused by failed or failing engine bearings?

Answer 3

Low oil temperatures.

Question 4

What is the principal advantage of using propeller reduction gears?

Answer 4

To enable the engine RPM to be increased with an accompanying increase in power and allow the propeller to remain at a lower, more efficient RPM.

Question 5

Which of the following will decrease volumetric efficiency in a reciprocating engine?

Answer 5

Improper valve timing, sharp bends in the induction system, and high carburetor air temperatures.

Question 6

Which of the following is a characteristic of a thrust bearing used in most radial engines?

Answer 6

Deep-groove ball.

Question 7

Which bearing is least likely to be a roller or ball bearing?

Answer 7

Master rod bearing (radial engine).

Question 8

The operating temperature valve clearance of a radial engine as compared to cold valve clearance is what?

Answer 8

greater.

Question 9

A nine-cylinder engine with a bore of 5.5 inches and a stroke of 6 inches will have a total piston displacement of what?

Answer 9

1,283 cubic inches.

Question 10

The five events of a four-stroke cycle engine in the order of their occurrence are what?

Answer 10

intake, compression, ignition, power, and exhaust.

Question 11

The primary concern in establishing the firing order for an opposed engine is to what?

Answer 11

provide for balance and eliminate vibration to the greatest extent possible.

Question 12

If fuel-air ratio is proper and ignition timing is correct, the combustion process should be completed…

Answer 12

Just after top center at the beginning of the power stroke.

Question 13

Grinding the valves of a reciprocating engine to a feather edge is likely to result in what?

Answer 13

preignition and burned valves.

Question 14

Which statement is correct regarding engine crankshafts?

Answer 14

Moveable counterweights serve to reduce torsional vibrations in an aircraft reciprocating engine.

Question 15

On which strokes are both valves on a four-stroke cycle reciprocating aircraft engine open?

Answer 15

Exhaust and intake.

Question 16

Which type of bearings are generally used for connecting rods and cam shafts?

Answer 16

Plain

Question 17

The actual power delivered to the propeller of an aircraft engine is called what?

Answer 17

brake horsepower.

Question 18

Cam-ground pistons are installed in some aircraft engines to what?

Answer 18

provide a better fit at operating temperatures.

Question 19

Using the following information, determine how many degrees the crankshaft will rotate with both the intake and exhaust valves seated.

Intake opens at 15 degrees BTDC
Exhaust opens 70 degrees BBDC
Intake closes 45 degrees ABDC
Exhaust closes 10 degrees ATDC

Answer 19

245 degrees.

Question 20

Some aircraft engine manufacturers equip their product with chocked or taper-ground cylinders in order to what?

Answer 20

provide a straight cylinder bore at operating temperatures.

Question 21

An aircraft reciprocating engine using hydraulic valve lifters is observed to have no clearance in its valve operating mechanism after the minimum inlet oil and cylinder head temperatures for takeoff have been reached. When can this condition be expected?

Answer 21

During normal operation.

Question 22

What tool is generally used to measure the crankshaft rotation in degrees?

Answer 22

Timing disk

Question 23

If an engine with a stroke of 6 inches is operated at 2,000 RPM, the piston movement within the cylinder will be what?

Answer 23

at maximum velocity 90 degrees after TDC.

Question 24

If the intake valve is opened too early in the cycle of operation of a four-stroke cycle engine, it may result in what?

Answer 24

backfiring into the induction system.

Question 25

Some cylinders barrels are hardened by what?

Answer 25

nitriding.

Question 26

Which statement is correct regarding a four-stroke cycle aircraft engine?

Answer 26

The intake valve closes on the compression stroke.

Question 27

On which part of the cylinder walls of a normally operating engine will the greatest amount of wear occur?

Answer 27

Near the top of the cylinder.

Question 28

During overhaul, reciprocating engine exhaust valves are checked for stretch...

Answer 28

with a contour or radius gauge.

Question 29

When is the fuel/air mixture ignited in a conventional reciprocating engine?

Answer 29

Shortly before the piston reaches the top of the compression stroke.

Question 30

Ignition occurs at 28 degrees BTDC on a certain four-stroke cycle engine, and the intake valve opens at 15 degrees BTDC. How many degrees of crankshaft travel after ignition does the intake valve open? (Consider one cylinder only.)

Answer 30

373 degrees.

Question 31

What is the purpose of the safety circlet installed on some valve stems?

Answer 31

To prevent valves from falling into the combustion chamber.

Question 32

Valve overlap is defined as the number of degrees of crankshaft travel...

Answer 32

during which both valves are off their seats.

Question 33

The valve clearance of an engine using hydraulic lifters, when the lifters are completely flat, or empty, should not exceed what?

Answer 33

a specified amount above zero.

Question 34

If the exhaust valve of a four-stroke cycle engine is closed and the intake valve is just closed, the piston is on the what?

Answer 34

compression stroke.

Question 35

Which of the following are factors in establishing the maximum compression ratio limitations of an aircraft engine?

Answer 35

Detonation characteristics of the fuel, design limitations of the engine, and the degree of supercharging.

Question 36

Full-floating piston pins are those which allow motion between the pin and what?

Answer 36

both the piston and the small end of the connecting rod.

Question 37

The primary purpose in setting proper valve timing and overlaps is to what?

Answer 37

obtain the best volumetric efficiency and lower cylinder operating temperatures.

Question 38

If the hot clearance is used to set the valves when the engine is cold, what will occur during operation of the engine?

Answer 38

The valves will open late and close early.

Question 39

What is the purpose of installing two or more springs on each valve in an aircraft engine?

Answer 39

To eliminate valve spring vibration or surging.

Question 40

During overhaul, the disassembled parts of an engine are usually degreased with some form of mineral spirits solvent rather than water-mixed degreasers primarily because what?

Answer 40

water-mixed degreaser residues may cause engine oil contamination in the overhauled engine.

Question 41

Why does the smoothness of operation of an engine increase with a greater number of cylinders?

Answer 41

The power impulses are spaced closer together.

Question 42

Compression ratio is the ratio between the what?

Answer 42

Cylinder volume with piston at bottom dead center and at top dead center.

Question 43

If the crankshaft runout readings on the dial indicator are plus .002 inch and minus .003 inch, the runout is what?

Answer 43

.005 inch.

Question 44

(1) Cast iron piston rings may be used in chrome-plated cylinders. (2) Chrome-plated rings may be used in plain steel cylinders. Regarding the above statements,

Answer 44

Both 1 and 2 are true.

Question 45

How is proper end-gap clearance on new piston rings assured during the overhaul of an engine?

Answer 45

By placing the rings in the cylinder and measuring the end gap with a feeler gauge.

Question 46

The volume of a cylinder equals 70 cubic inches when the piston is at bottom center. When the piston is at the top of the cylinder, the volume equals 10 cubic inches. What is the compression ratio?

Answer 46

7:1

Question 47

When cleaning aluminium and magnesium engine parts, it is inadvisable to soak them in solutions containing soap because what?

Answer 47

Some of the soap will become impregnated in the surface of the material and subsequently cause engine oil contamination and foaming.

Question 48

What is the purpose of a power check on a reciprocating engine?

Answer 48

To determine satisfactory performance.

Question 49

What will be the likely result if the piston ring gaps happen to be aligned when performing a differential pressure compression check on a cylinder?

Answer 49

A worn or defective ring(s) indication.

Question 50

Which of the following will be caused by excessive valve clearance of a cylinder on a reciprocating aircraft engine?

Answer 50

Reduced valve overlap period.

Question 51

The floating control thermostat, used on some reciprocating engine installations, helps regulate oil temperature by what?

Answer 51

controlling air flow through the oil cooler.

Question 52

Which of the following would indicate a general weak-engine condition when operated with a fixed-pitch propeller or test club?

Answer 52

Lower than normal static RPM, full throttle operation.

Question 53

What is required by 14 CFR Part 43 Appendix D when performing an annual/100-hour inspection on a reciprocating engine aircraft?

Answer 53

Cylinder compression check.

Question 54

After spark plugs from an opposed engine have been serviced, in what position should they be reinstalled?

Answer 54

Next in firing order to the one from which they were removed and swapped bottom to top.

Question 55

As the pressure is applied during a reciprocating engine compression check using a differential pressure tester, what would a movement of the propeller in the direction of engine rotation indicate?

Answer 55

The piston was positioned past top dead center.

Question 56

Excessive valve clearance results in the valves opening...

Answer 56

late and closing early.

Question 57

During routine inspection of a reciprocating engine, a deposit of small, bright, metallic particles which do not cling to the magnetic drain plug is discovered in the oil sump and on the surface of the oil filter. This condition...

Answer 57

may be a result of abnormal plain type bearing wear and is cause for further investigation.

Question 58

A characteristic of dyna-focal engine mounts as applied to aircraft reciprocating engines is that the what?

Answer 58

shock mounts point toward the engine's center of gravity.

Question 59

If metallic particles are found in the oil filter during an inspection, ...

Answer 59

the cause should be identified and corrected before the aircraft is released for flight.

Question 60

If the oil pressure gauge fluctuates over a wide range from zero to normal operating pressure, the most likely cause is what?

Answer 60

low oil supply.

Question 61

What special procedure must be followed when adjusting the valves of an engine equipped with a floating cam ring?

Answer 61

Eliminate cam bearing clearance when making valve adjustment.

Question 62

Which of the following is most likely to occur if an overhead valve engine is operated with inadequate valve clearances?

Answer 62

The valves will not seat positively during start and engine warmup.

Question 63

Excessive valve clearances will cause the duration of valve opening to what?

Answer 63

decrease for both intake and exhaust valves.

Question 64

What does valve overlap promote?

Answer 64

Better scavenging and cooling characteristics.

Question 65

At what speed must a crankshaft turn if each cylinder of a four-stroke cycle engine is to be fired 200 times a minute?

Answer 65

400 RPM.

Question 66

Engine crankshaft runout is usually checked?

Answer 66

during engine overhaul and after "prop strike" or sudden engine stoppage.

Question 67

Before attempting to start a radial engine that has been shut down for more than 30 minutes, ...

Answer 67

turn the propeller by hand three to four revolutions in the normal direction of rotation to check for liquid luck.

Question 68

An engine misses in both the right and left positions of the magneto switch. The quickest method for locating the trouble is to what?

Answer 68

check for one or more cold cylinder.

Question 69

A hissing sound from the exhaust stacks when the propeller is being pulled through manually indicates what?

Answer 69

exhaust valve blow-by.

Question 70

If the oil pressure of a cold engine is higher than at normal operating temperatures, the what?

Answer 70

engine's lubrication system is probably operating normally.

Question 71

If an engine operates with a low oil pressure and a high oil temperature, the problem may be caused by a what?

Answer 71

leaking oil dilution valve.

Question 72

Which fuel/air mixture will result in the highest engine temperature (all other factors remaining constant)?

Answer 72

A mixture leaner than a manual lean mixture of 0.60.

Question 73

If an engine cylinder is to be removed, at what position in the cylinder should the piston be?

Answer 73

Top dead center.

Question 74

The horsepower developed in the cylinders of a reciprocating engine is known as the what?

Answer 74

indicated horsepower

Question 75

Engine operating flexibility is the ability of the engine to what?

Answer 75

run smoothly and give the desired performance at all speeds.

Question 76

Standard aircraft cylinder oversizes usually range from 0.010 inch to 0.030 inch. Oversize on automobile engine cylinders may range up to 0.100 inch. This is because aircraft engine cylinders what?

Answer 76

have relatively thin walls and may be nitrided.

Question 77

If the ignition switch is moved from BOTH to either LEFT or RIGHT during an engine ground check, normal operation is usually indicated by a slight what?

Answer 77

drop in torque meter pressure indication.

Question 78

During ground check an engine is found to be rough-running, the magneto drop is normal, and the manifold pressure is higher than normal for any given RPM. The trouble may be caused by what?

Answer 78

A dead cylinder.

Question 79

What is the best indication of worn valve guides?

Answer 79

high oil consumption.

Question 80

By use of a differential pressure compression tester, it is determined that cylinder 3 of a nine-cylinder radial engine will not hold pressure after the crankshaft has been rotated 260 degrees from top dead center compression stroke cylinder 1. How can this indication usually be interpreted?

Answer 80

A normal indication.

Question 81

When does valve overlap occur in the operation of an aircraft reciprocating engine?

Answer 81

At the end of the exhaust stroke and the beginning of the intake stroke.

Question 82

What is love?

Answer 82

Baby, don't hurt me. Don't hurt me no more.

Question 83

What is an advantage of using metallic-sodium filled exhaust valves in aircraft reciprocating engines?

Answer 83

Reduced valve operating temperatures.

Question 84

Valve clearance changes on opposed-type engines using hydraulic lifters are accomplished by what?

Answer 84

push rod replacement.

Question 85

What is likely to occur if a reciprocating engine is operated at high power settings before it is properly warmed up?

Answer 85

Oil starvation of bearings and other parts.

Question 86

An increase in manifold pressure with a constant RPM will cause the bearing load in an engine to what?

Answer 86

increase.

Question 87

Direct mechanical push-pull carburetor heat control linkages on the diverter valve will be contacted...

Answer 87

before the stop at the control lever is reached in both HOT and COLD positions.

Question 88

Reduced air density at high altitude has a decided effect on carburetion, resulting in a reduction of engine power by what?

Answer 88

excessively enriching the fuel/air mixture.

Question 89

Increased water vapor (higher relative humidity) in the incoming air to a reciprocating engine will normally result in which of the following?

Answer 89

Decreased engine power at a constant RPM and manifold pressure.

Question 90

(1) Preignition is caused by improper ignition timing. (2) Detonation occurs when an area of the combustion chamber becomes incandescent and ignites the fuel/air mixture in advance of normal timed ignition. Regarding the above statements,

Answer 90

Neither 1 nor 2 is true.

Question 91

Which of the following engine servicing operations generally requires pre-oiling prior to starting the engine?

Answer 91

Engine installation.

Question 92

During the inspection of an engine control system in which push-pull control rods are used, the threaded rod ends should what?

Answer 92

be checked for the amount of thread engagement by means of the inspection holes.

Question 93

Which of the following conditions would most likely lead to detonation?

Answer 93

Use of fuel with too low an octane rating.

Question 94

An unsupercharged aircraft reciprocating engine, operated at full throttle from sea level, to 10,000 feet, provided the RPM is unchanged, will what?

Answer 94

lose power due to the reduced density of the air drawn into the cylinders.

Question 95

Which of the following would most likely cause a reciprocating engine to backfire through the induction system at low RPM operation?

Answer 95

Lean mixture.

Question 96

How may it be determined that a reciprocating engine with a dry sump is pre-oiled sufficiently?

Answer 96

Oil will flow from the engine return line or indicator port.

Question 97

What is the basic operational sequence for reducing power output of an engine equipped with a constant-speed propeller?

Answer 97

Reduce the manifold pressure, then the RPM.

Question 98

Which statement pertaining to fuel/air ratios is true?

Answer 98

The mixture ratio which gives the best power is richer than the mixture ratio which gives maximum economy.

Question 99

Backfiring through the carburetor generally results from the use of what?

Answer 99

An excessively lean mixture.

Question 100

Which of these conditions will cause an engine to have an increased tendency to detonate?

Answer 100

High manifold pressure or high intake air temperature.

Question 101

When will small induction system air leaks have the most noticeable effect on engine operation?

Answer 101

At low RPM.

Question 102

To reduce the power output of an engine equipped with a constant-speed propeller and operating near maximum BMEP, the...

Answer 102

manifold pressure is reduced with the throttle control before RPM is reduced with the propeller control.

Question 103

One of the best indicators of reciprocating engine combustion chamber problems is what?

Answer 103

spark plug condition.

Question 104

What could cause excessive pressure build up in the crankcase of a reciprocating engine?

Answer 104

Plugged crankcase breather.

Question 105

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Answer 105

Decreases valve overlap.

Question 106

To what altitude will a turbo charged engine maintain sea level pressure?

Answer 106

Critical altitude.

Question 107

If air is heard coming from the crankcase breather or oil filler during a differential compression check, what is this an indication of?

Answer 107

Piston ring leakage.

Question 108

One cause of afterfiring in an aircraft engine is what?

Answer 108

an excessively rich mixture.