Reciprocating Engines

Question 1

What is the purpose of dynamics dampers on crankshafts?

Answer 1

They reduce engine vibrations

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 assemblies.

Question 4

Name the different types of piston rings.

Answer 4

Oil control, compression, and oil scrapper

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 (not sudden stoppage)

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 carburators?

Answer 13

3 to 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 stud or Heli-Coil Insert

Question 16

What is the 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, pistons rings and pistons are adequately sealing.

Question 19

What is meant when it is said that an engine PART is withing “serviceable limits”?

Answer 19

A part that is within the manufacture’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 an engine 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 precious operating history.

Question 21

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

Answer 21

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

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

How is a cylinder barrel inspected for out of roundness?

Answer 23

You must measure with a (cylinder bore gage or a telescopic gauge and micrometer, or an inside micrometer ) the top of the cylinder and the skirt. These two reading should be taken 90 degrees to each other.

Question 24

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

Answer 24

No, a thermocouple is used as the electrical source.

Question 25

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

Answer 25

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

Question 26

What are some indications of induction system leakage?

Answer 26

Low power and uneven running.