Reciprocating Engines

Question 1

What is the purpose of crankshaft dynamic dampers?

Answer 1

To reduce engine vibration.

Question 2

What types of connecting rods are commonly found in radial engines?

Answer 2

Master and articulated rod assemblies.

Question 3

What are the different types of piston rings?

Answer 3

Compression, oil control, and oil scraper.

Question 4

What is the purpose of oil control rings?

Answer 4

Oil control rings regulate the thickness of the film on the cylinder wall.

Question 5

What is the purpose of valve overlap?

Answer 5

It permits better volumetric efficiency and lowers the cylinder operating temperature.

Question 6

What is the running valve clearance on engines equipped with hydraulic valve lifters?

Answer 6

Zero.

Question 7

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

Answer 7

Lack of combustion in that cylinder.

Question 8

What types of bearings are in general use in reciprocating engines?

Answer 8

Plain, ball, and roller.

Question 9

Name at least one part of an inspection that should be made after a propeller strike (not sudden stoppage).

Answer 9

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

Question 10

How is a cylinder barrel inspected for out of roundness?

Answer 10

A cylinder bore gauge(or a telescopic gauge and micrometer, or an inside micrometer) can be used to measure at the top of the cylinder and also at the skirt. Two readings should be taken, 90° to each other.

Question 11

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

Answer 11

Remove the loose stud, and inspect the hole for size and the condition of the threads. It may be necessary to use a suitable oversize stud.

Question 12

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

Answer 12

The engine will not idle properly.

Question 13

What are some indications of induction system leakage?

Answer 13

Low power and uneven running.

Question 14

What may be the result of incorrect installation of piston rings?

Answer 14

Excessive oil consumption.

Question 15

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

Answer 15

Perform a cylinder compression test to identify the faulty cylinder.

Question 16

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

Answer 16

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

Question 17

How are piston ring gaps installed relative to each other on a piston, and why?

Answer 17

Compression ring gaps should be installed in staggered positions (not aligned) around the piston in order to prevent excessive blow-by.

Question 18

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

Answer 18

A part that is within serviceable limits will not likely wear to the point of causing engine failure within the next time between overhaul (TBO) interval.

Question 19

When an engine is rebuilt by the manufacturer, how is it’s operating history affected?

Answer 19

A rebuilt engine is considered to have no previous operating history and can therefore be issued a zerotime record.

Question 20

What is used in an aircraft engine to help prevent valve surge or float from occuring?

Answer 20

Two or more springs on each valve.