56 - Reciprocsting Engines - Conponents, Operating Principles, Characteristics

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

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

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

Answer 4

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

Question 5

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

Answer 5

Deep-groove ball.

Question 6

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

Answer 6

1,283 cubic inches.

Question 7

The distance that is one-half of the diameter of a circle is known as

Answer 7

Radius

Question 8

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

Answer 8

intake, compression, ignition, power, and exhaust

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

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

Answer 11

preignition and burned valves.

Question 12

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

Answer 12

Exhaust and intake.

Question 13

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

Answer 13

Plain.

Question 14

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

Answer 14

Brake horsepower

Question 15

Cam-ground pistons are installed in some aircraft engines to

Answer 15

provide a better fit at operating temperatures.

Question 16

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

Answer 16

provide a straight cylinder bore at operating temperatures.

Question 17

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

Answer 17

at maximum velocity 90° after TDC.

Question 18

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

Answer 18

backfiring into the induction system.

Question 19

Some cylinder barrels are hardened by

Answer 19

nitriding.

Question 20

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

Answer 20

The intake valve closes on the compression stroke.

Question 21

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

Answer 21

Near the top of the cylinder.

Question 22

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

Answer 22

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

Question 23

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

Answer 23

373 °

Question 24

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

Answer 24

To prevent valves from falling into the combustion chamber.