Reciprocating Engines

Question 1

What are the basic types of configurations of reciprocating engines?

Answer 1

Inline
Opposed
V-type
Radial

Question 2

In what position should the crankshaft be when a magneto is being timed to the engine?

Answer 2

The piston in cylinder number 1 should be in the correct position for ignition to occur. This is normally about 360° before top center on the compression stroke.

Question 3

What is checked on engine runup to determine the operation condition of the engine?

Answer 3

-Idling RPM and manifold pressure
-Engine acceleration
-Maximum static RPM and manifold pressure
-Magneto drop
-Ignition switch safety check
-Propeller pitch change
-Propeller feathering
-Oil pressure
-Fuel pressure
-Fuel flow.

Question 4

What is a hydraulic lock in an aircraft engine?

Answer 4

Oil has drained past the piston rings and filled the combustion chamber of cylinders that are below the center line of the engine. If the crankshaft is turned over with this oil in the cylinder it will lock, and there is a probability that the piston, cylinder, or connecting rod will be damaged.

Question 5

How is hydraulic lock removed from an aircraft engine?

Answer 5

Remove a spark plug from the locked cylinder and drain all the oil out. Clean the spark plug and replace it.

Question 6

What are the strokes of a 4-stroke reciprocating engine?

Answer 6

Intake
Compression
Power
Exhaust

Question 7

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

Answer 7

-Piston rings not seating or broken
-Valves not seating or burned

Question 8

What is a low-tension ignition system?

Answer 8

It is an ignition system using a magneto with a brush-type distributor and a coil that has no secondary wiring. Low voltage is directed from the magneto to a transformer mounted on the cylinder head. here the low voltage is boosted to a high voltage and is directed through a very short high-tension lead to the spark plug. There is one transformer for each spark plug.

Question 9

What are some advantages of a horizontally opposed engine?

Answer 9

-Lower power to weight ratio
-Ideal for installation on aircraft wings
-Low vibration characteristics

Question 10

How can you determine the firing order of an 18-cylinder radial engine?

Answer 10

Begin with cylinder 1, and add 11 or subtract 7, whichever will keep the numbers between 1 and 18.

1-12-5-16-9-2-13-6-17-10-3-14-7-18-11-4-15-8

Question 11

What is a floating cam ring on a large radial engine?

Answer 11

It is a cam ring that rides on a shelf-type bearing with a large amount of clearance between the bearing and the ring. When adjusting the valves on an engine with a floating cam ring, the pressure of the valve springs on the opposite side of the engine must be removed so the cam ring will be tight against the bearing for the valves being adjusted.

Question 12

Why is valve clearance adjusted on radial engines, but not on most horizontally opposed engines?

Answer 12

Most horizontally opposed engines have hydraulic valve lifters that keep all the clearance out of the valve train. Radial engines have solid lifters.

Question 13

Why are both the hot and cold valve clearances given for most radial engines?

Answer 13

The hot clearance is given for valve timing purposes. The timing is adjusted with the valves in cylinder number one, set with the hot clearance. When the timing is set, all of the valves are adjusted to their cold clearance.

Question 14

Why is it important to preserve engines that will not be operated for an extended period of time?

Answer 14

Moisture will accumulate in the engine, initiating the corrosion process which can ruin the engine.

Question 15

Preservation for temporary storage is valid for engines that will be out of service for how many days?

Answer 15

30 to 90 days.

Question 16

What should be done to the cylinders to protect them from rust and corrosion when preparing the engine for long-time storage?

Answer 16

Spray a preservative oil inside the cylinders and replace the spark plugs with desiccant plugs.

Question 17

What is specific fuel consumption (SFC)?

Answer 17

SFC is a measure of the economical use of fuel, which is the fuel weight in pounds per hour per horsepower:

SFC=(pounds fuel/hour)/horsepower

Question 18

What must be inspected to determine the airworthiness of an engine installation?

Answer 18

-The propeller
-Lubrication system
-Ignition system
-Fuel metering system
-Cooling system
-Exhaust system

Question 19

Where can you find the correct grade of fuel and amount of engine lubricating oil for an aircraft engine?

Answer 19

In the TCDS for the aircraft.

Question 20

What are the basic steps in troubleshooting an engine installation?

Answer 20

-Know how the system should operate
-Observe how the system is operating.
-Divide the system into smaller parts to find the trouble.
-Look for the obvious problems first.

Question 21

Where do you find instructions for removing an engine from an aircraft?

Answer 21

In the aircraft maintenance manual.

Question 22

What must normally be done to a nose-wheel airplane before removing an engine?

Answer 22

The tail of the airplane must be supported.

Question 23

What should be used to cover the ends of fuel and oil lines that have been disconnected from the engine?

Answer 23

The correct plugs or caps. Never cover the endo f a line with tape.

Question 24

What is meant by a QEC engine assembly?

Answer 24

An engine that has been prepared for a quick engine change. The engine is on its mount and all of the accessories are installed. A minimum of time is required to change engines. All that is needed is for the controls, wiring, and fluid lines to be connected to the firewall.

Question 25

What is meant by rigging the engine controls they have some “cushion”?

Answer 25

The control on the engine component must contact its stop before the control handle in the flight deck reaches its stop. This causes the control handle to spring back a slight amount when it is moved to the extent of its travel.

Question 26

What are two ways of pre-oiling an engine?

Answer 26

-Before the spark plugs are installed and after the oil tank or sump is filled, turn the engine over with the starter until oil runs out of the fitting to which the oil pressure gauge connects.

-Use a pre-oiler tank. Air pressure forces oil through all of the passages until some of it flows from the oil pressure gauge fitting.

Question 27

What checks should be made to determine the proper operation of a reciprocating egine installation?

Answer 27

-Idle RPM and mixture
-Static RPM
-Propeller pitch change operation
-Magneto check
-Ignition switch safety check
-Carburetor heat check

Question 28

What is the purpose of a cold cylinder check?

Answer 28

A cold cylinder check determines which cylinder is not firing. Run the eninge for a few minuts at the speed, and on the magneto, at which it runs roughest. Shut it down and feel the exhaust stack near the cylinder head. The cylinder with the stack that is not as hot as the others is the cylinder that has not been firing.

Question 29

How is fuel ignited in a diesel cycle eninge?

Answer 29

The diesel cycle depends on high compression pressures to provide for the ignition the the air-fuel charge in the cylinder.