Reciprocating Engines

Question 1

Define the term “operating flexibility” in regards to aircraft engines.

Answer 1

The ability of an engine to run smoothly and give desired performance at all speeds from idling to full-power output.

Question 2

How are conventional reciprocating engines classified?

Answer 2

According to cylinder arrangement with respect to the crankshaft or method of cooling.

Question 3

What are the different types of piston rings?

Answer 3

Compression
Oil Control
Scraper

Question 4

What are the main causes of a cylinder having low compression?

Answer 4

Broken piston rings
Rings not seating properly
Burnt valves
Poorly seating valves

Question 5

What is the purpose of the oil control rings?

Answer 5

To control the thickness of the oil film on the cylinder walls.

Question 6

What may be the result of installing piston rings incorrectly?

Answer 6

Excessive oil consumption.

Question 7

What type of piston rods are commonly found in radial engines?

Answer 7

Master and Articulating Rod Assembly.

Question 8

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

Answer 8

Plain
Roller
Ball

Question 9

What is the indication of valve blow-by?

Answer 9

Hissing or whistling when pulling the propeller through by hand.

Question 10

What is the purpose of using more than one spring for valve closing?

Answer 10

Each spring, installed one inside the other, will resonate at a different engine speed, eliminating valve float.

Question 11

What is the purpose of valve overlap?

Answer 11

Better volumetric efficiency and lower cylinder operating temperature.

Question 12

Describe the inspection you would give the valve springs during engine overhaul.

Answer 12

Cleaned thoroughly, then visually inspected for evidence of overheating, cracks, broken ends, and compression strength.

Question 13

What is the purpose of using valves with sodium filled stems?

Answer 13

The sodium is an excellent heat conductor which dissipates heat.

Question 14

What causes engine sudden stoppage?

Answer 14

Striking an object or engine seizure due to internal damage.

Question 15

What type of inspection must be made after sudden stoppage of an engine?

Answer 15

A complete engine tear down and inspection.

Question 16

What is the purpose of the crankshaft dynamic dampers used in aircraft engines?

Answer 16

To overcome forces which cause deflection of the crankshaft and torsional vibration.

Question 17

How would you make a “runout” check on a crankshaft that is still installed in the engine?

Answer 17

Remove Prop. from crankshaft.
Attach dial indicator to front of crankcase.
Adjust gauge needle so it touches shaft.
Rotate crankshaft to check for misalignment.

Question 18

What is detonation?

Answer 18

The instantaneous explosive burning of the last portion of the charge across the combustion chamber.

Question 19

What cylinder is engine to magneto timing based on?

Answer 19

The number one cylinder.

Question 20

What is engine sudden speed reduction?

Answer 20

When the propeller strikes an object but continues to run.

Question 21

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

Answer 21

If the valves, piston rings, and pistons are adequately sealing the combustion chamber.

Question 22

How can a cold cylinder be located on a double row radial engine?

Answer 22

Infrared laser thermometer.

Question 23

What instrument can be used to check bore for out of round?

Answer 23

Inside Micrometer.

Question 24

What would a cold cylinder indicate?

Answer 24

That there has been no combustion inside the cylinder.

Question 25

Where is a crack most likely to occur on a piston?

Answer 25

Where the piston pin/wrist pin connects.

Question 26

What should be done to a nose wheel airplane before removing the engine?

Answer 26

Support the tail.

Question 27

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

Answer 27

Zero

Question 28

What lever is used to adjust the manifold pressure in a reciprocating engine?

Answer 28

Throttle

Question 29

On an engine with a fixed pitch propeller, what is the relationship between manifold pressure and RPM?

Answer 29

As RPM increases, MAP increases.

Question 30

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

Answer 30

Remove the loose stud and inspect the hole for size and thread condition. It may be necessary to use a suitable oversized stud.

Question 31

What is meant by an engine part being within serviceable limits?

Answer 31

The part will not likely wear to the point of causing engine failure within the next time between overhaul.

Question 32

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

Answer 32

The engine will not idle properly.