Powerplant

Front 1

What is the purpose of dynamic dampers on crankshafts?

Back 1

They reduce engine vibration. Dampers are used to overcome forces which cause deflection of the crankshaft and torsional vibration. These forces are generated by the power impulses of the pistons. Crankshaft vibrations are reduced by placing floating dampers (weights) in the counterweight assembly, particularly in a single throw type crankshaft.

Hint 1

None

Front 2

What types of bearings are generally found in reciprocating engines?

Back 2

Plain, ball and roller bearings. Plain bearings are generally used for crankshaft, camshafts and connecting rods. Roller bearings are used primarily as crankshaft main bearings. And all bearings are used for supercharger impeller shaft bearings and Crankshaft thrust bearings or large radial engines.

Front 3

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

Back 3

No. Radial engines use master and articulating rod assemblies.

Front 4

Name different types of piston rings

Back 4

Oil control, compression and oil scraper

Front 5

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

Back 5

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

Front 6

What could result from incorrectly installed piston rings?

Back 6

Excessive oil consumption

Front 7

What purpose do oil control rings serve?

Back 7

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

Front 8

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

Back 8

Two or more springs are used on each valve.

Valve springs will resonate (or surge) has certain engine speeds. If only one spring is used, the valve will float as the spring surges. To eliminate this problem, two springs (one inside the other) are installed on each valve. Each spring will resonate at a different engine speed, eliminating valve float.

Front 9

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

Back 9

Zero

Front 10

What is the purpose of valve overlap?

Back 10

It allows better volumetric efficiency and lowers cylinder operating temperatures.

Front 11

How are conventional reciprocating engines classified?

Back 11

They are classified according to cylinder arrangement with respect to the crankshaft (in-line, v-type, radial, and opposed), or according to method of cooling (liquid cooled or air cooled).

Front 12

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

Back 12

Broken piston rings, rings that are not seating properly, burnt valves, and Poorly seating valves.

Front 13

What is the indication of valve blowby?

Back 13

Valve blowby is indicated by a hissing or whistle when pulling the propeller through by hand. A cylinder compression check should be completed to identify the faulty cylinder.

Front 14

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

Back 14

They should be cleaned thoroughly, then visually inspected for evidence of overheating, cracks, broken ends, and compression strength.

Front 15

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

Back 15

Some intake and exhaust valve stems are hollow and partially filled with metallic sodium. Sodium is used because it is an excellent heat conductor. The sodium melts at a relatively low temperature, and as the valve moves up and down the sodium is circulated, carrying the heat from the valve head to the stem. Then the heat is dissipated to the cylinder head.

Front 16

What causes engine certain stoppage?

Back 16

Striking an object or engine seizure due to internal damage.

Front 17

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

Back 17

Most manufacturers require a complete engine teardown and inspection.

Front 18

How would you make a run-out check with the crankshaft that is still installed in the engine?

Back 18

Remove the propeller from the crankshaft and attach a dial indicator gauge to the front of the crank case. Adjust the position of the gauge needle so that it is touching the shaft. Rotate the crankshaft and check for misalignment. Refer to the table of limits to check the allowance. Flanged crankshafts must also be checked from the front face of the flange.

Front 19

Normal combustion is when the fuel air mixture burns had a uniform rate across the combustion chamber. The temperature and pressure within the cylinder rises at a normal rate as the mixture of burns. All fuels have critical limits of temperature and compression, beyond this limit they will ignite spontaneously and burn with explosive violence.

Back 19

Normal combustion is when the fuel air mixture burns had a uniform rate across the combustion chamber. The temperature and pressure within the cylinder rises at a normal rate as the mixture of burns. All fuels have critical limits of temperature and compression, beyond this limit they will ignite spontaneously and burn with explosive violence.

Front 20

What is detonation?

Back 20

Normal combustion is when the fuel air mixture burns at a uniform rate across the combustion chamber. The temperature and pressure within the cylinder rises at a normal rate as the mixture burns. All fuels have critical limits of temperature and compression, beyond this limit they will ignite spontaneously and burn with explosive violence. This instantaneous explosive burning of the last portion Of the charge is called detonation.

Front 21

What cylinder his engine to magneto timing based on?

Back 21

The number one cylinder. Timing is usually set for around 30° before top dead center of the compression stroke.

Front 22

What is engine sudden speed reduction?

Back 22

This occurs when the propeller strikes an object but continues to run. When this occurs, a thorough external engine inspection should be carried out, including an oil analysis. The propeller should also be inspected along with a run-out check.

Front 23

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

Back 23

A cold cylinder check can be made with a cold cylinder indicator, sometimes called a “magic wand”, to locate any cylinder that has a temperature lower than the normal operating temperature of the other cylinders. On most horizontal engines you can simply place your hand on the rocker box to check for a cold cylinder.