Reciprocating engines

Question 1

What is the purpose of dynamic dampers on crankshafts?

Answer 1

They reduce engine vibration

Question 2

What types of bearings are generally found in reciprocating engines?

Answer 2

Plain, ball and roller bearings

Question 3

Are the connecting rods used in each cylinder of a radial engine the same? Explain

Answer 3

No. Radial engines use master and articulating rod assemblies

Question 4

Name the different types of piston rings

Answer 4

Oil control, compression and oil scraper

Question 5

Where should piston ring gaps be installed relative to each other and why?

Answer 5

Compression ring gaps should be staggered so that they do not align. This prevents excessive blow-by.

Question 6

What could result from incorrectly installed piston rings?

Answer 6

Excessive oil consumption

Question 7

What purpose do oil control rings serve?

Answer 7

They regulate the thickness of the oil film of the cylinder walls

Question 8

What is used to help prevent valve surge or floating in an aircraft engine?

Answer 8

Two or more springs are used on each valve

Question 9

On engines equipped with hydraulic valve lifters, what should the running valve clearance be?

Answer 9

Zero

Question 10

What is the purpose of valve overlap?

Answer 10

It allows better volumetric efficiency and lowers cylinder operating temperatures

Question 11

When troubleshooting a running engine malfunction, what does a cold cylinder indicate?

Answer 11

No combustion in that cylinder

Question 12

Name at least one part of an inspection that should be made after a propeller strike

Answer 12

1) Inspect the engine mounts, crankcase and nose section for damage
2) Inspect the oil screens/filters for metal particles
3) Inspect the propeller drive or crankshaft for misalignment

Question 13

What is the fuel pressure range on float type carburetors?

Answer 13

3-5 psi

Question 14

What publication is used to check an engine for normal operation?

Answer 14

The manufacturer’s maintenance manual

Question 15

What should be done to repair a loose stud in an engine crankcase?

Answer 15

Remove the loose stud, inspect the hole for size and condition of the threads. It may be necessary to use a suitable oversized stud or heli-coil insert.

Question 16

What is an indication that a primer is leaking or is open during engine operation?

Answer 16

The engine will not idle properly

Question 17

What procedure should be followed when valve blow-by is indicated by a hissing sound on a reciprocating engine when pulling the propeller through?

Answer 17

Perform a cylinder compression test to identify the faulty cylinder

Question 18

What factors about the condition of an engine can be learned by studying the results of a compression test?

Answer 18

The results of a compression test determine if the valves, piston rings and pistons are adequately sealing

Question 19

What is meant when it is said that an engine part is within serviceable limits?

Answer 19

A part that is within the manufacturer’s serviceable limits and can be used in an engine, will not likely wear to the point of causing engine failure within the next time between overhaul TBO interval

Question 20

When an engine is overhauled, how is its total time affected? When it is rebuilt, how is its operating history affected?

Answer 20

Overhauled- the total time on the engine must be continued and the time since major overhaul is entered into the logbook.
Rebuilt- if the manufacturer rebuilds the engine it is granted a zero time status and is considered to have no previous operating history.

Question 21

Name some of the precautions that should be performed prior to engine replacement

Answer 21

Disconnect the battery, turn off the fuel valves, chock the wheels and install a tail stand if necessary

Question 22

When inspecting a piston, where are cracks most likely to be found?

Answer 22

Highly stressed areas, base of piston bosses, inside at the junction of the bore and the walls and ring lands

Question 23

What is the purpose of performing a compression test?

Answer 23

To determine if the valves, pistons and rings are sealing properly

Question 24

What tools or instruments are used to inspect a cylinder barrel for out-of-roundness?

Answer 24

A dial indicator or an inside micrometer is usually used to measure the top of the cylinder at the skirt ( a telescopic gauge and micrometer can also be used). Two readings should be taken 90* to each other

Question 25

A weak cylinder is found during a compression check, what must be inspected?

Answer 25

Check that pressure is transmitted equally in all directions

Question 26

What purpose does an oil analysis serve?

Answer 26

Metal particles in the oil shows normal and abnormal wear of the engine. This helps in evaluating the engine’s internal condition

Question 27

What inspection should be performed on an engine that has been in storage?

Answer 27

Inspect for corrosion damage

Question 28

Where would a carburetor air temperature bulb be located?

Answer 28

In the ram air intake duct

Question 29

Name the basic components of a fuel indicator system

Answer 29

The transmitter and the indicator

Question 30

What unit of measure is usually used to indicate fuel flow?

Answer 30

Pounds or gallons per hour

Question 31

Why is fuel flow monitored?

Answer 31

To determine the fuel consumption and engine performance

Question 32

What does the manifold gauge indicate and how is it calibrated?

Answer 32

It measures the absolute pressure in the engine manifold and is calibrated in inches of mercury

Question 33

What directly controls manifold pressure?

Answer 33

Throttle opening and engine rpm

Question 34

During engine operation, where should the propeller control be set when checking the manifold pressure?

Answer 34

Low pitch and high rpm

Question 35

Is the aircraft electrical system required to power a cylinder head temperature gauge?

Answer 35

No, it is powered by a thermocouple

Question 36

What are the possible indications of an oil pressure transmitter or indicator malfunction?

Answer 36

A severe or sudden drop in oil pressure while the oil temperature remains normal and the oil supply remains full

Question 37

What does a tachometer indicate in a reciprocating engine?

Answer 37

Engine rpm

Question 38

Where should the thermocouple be installed on a reciprocating engine using a single probe cylinder head temperature system?

Answer 38

On the hottest cylinder