Engine Components and Cylinder Numbering

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Questions and Answers

Which mixture ratio is considered the leanest?

14:1

10:1

8:1

16:1 (correct)

What is the mixture ratio that provides the best power output?

15:1

12:1

14:1 (correct)

16:1

What should be done to the mixture as the aircraft ascends to maintain optimal performance?

The mixture must be leaned (correct)

The throttle must be opened

The throttle must be closed

The mixture must be richened

What is the chemically 'perfect' or Stoichiometric mixture ratio?

12:1 Signup and view all the answers

What mixture setting do manufacturers commonly choose to avoid overheating the engine?

Full rich Signup and view all the answers

At what valve position will the mixture be when set to idle cut off?

Fully closed Signup and view all the answers

What is 'lean best power' in relation to engine performance?

The mixture ratio that provides maximum rpm or manifold pressure Signup and view all the answers

What is the richest mixture an engine can operate safely at?

15:1 Signup and view all the answers

What is the role of the oil suction screen in an engine?

To remove large particles that could damage the pump Signup and view all the answers

When should the Lycoming suction screen typically be serviced?

At TBO Signup and view all the answers

How is the flow of air into an engine primarily controlled?

With a throttle valve in the induction system Signup and view all the answers

What effect does a fully closed throttle valve have on engine performance?

Generating minimum power Signup and view all the answers

What is the correct action for disposing of exhausted oil filters?

They are cut open, drained and inspected for metal contamination Signup and view all the answers

Which control in the cockpit operates the butterfly valve in a carburetor?

The throttle control Signup and view all the answers

What is the function of the butterfly valve in a carburetor?

Air flow regulation Signup and view all the answers

What does the term 'mixture ratio' refer to in aviation engines?

The ratio of air to fuel in the mixture Signup and view all the answers

What is the main purpose of the float bowl vent in a carburetor?

To allow atmospheric or intake pressure into the bowl for positive fuel flow through the discharge nozzle Signup and view all the answers

What happens to the air/fuel mixture when the throttle is opened quickly in a carburetor?

The mixture becomes leaner because air accelerates quicker than fuel Signup and view all the answers

How is the mixture controlled on most light aircraft during ascent?

By the pilot adjusting controls manually Signup and view all the answers

What is the recommended method to shut down an aircraft piston engine?

By turning off the ignition switch Signup and view all the answers

What is the standard procedure for leaning the engine during flight?

Push forward the mixture to peak EGT and pull back for a 25 degree drop Signup and view all the answers

What is the correct approach to lean some high-performance engines?

Push forward the mixture to peak EGT and pull back for a 25 degree drop Signup and view all the answers

What immediate action should be taken when a backfire occurs in an aircraft engine?

Reduce power and verify fuel mixture settings Signup and view all the answers

Which component is responsible for injecting extra fuel in times of high demand?

The mechanical fuel pump Signup and view all the answers

Study Notes

Cylinder Numbering

Lycoming 4-cylinder engine: C, D, 1, 3, A, 4, B, 2
Continental 4-cylinder engine: C, D, 1, 3, A2, B4,
Lycoming 6-cylinder engine: C6, B4, A2, F5, E3,
Continental 6-cylinder engine: D, 1, 3E, 5F, 2A, 4, B6, C

Major Engine Components

Crankcase: A component of the engine that contains the cylinders (image shown in purple)
Valve: Mechanical component that opens and closes to allow flow of gases.
Connecting rod: Connects the piston to the crankshaft
Camshaft: Used to coordinate valve opening and closing
Piston: Moves up and down inside the cylinder
Piston pin: Connects the piston to the connecting rod
Cylinder: The part of the engine containing the piston.
Compression ring: Rings that seal the cylinder walls to prevent leakage.

Piston Rings

Concave: A type of piston head
Truncated cone: A type of piston head
Domed: A type of piston head
Flat: A type of piston head
Oil control ring: A ring that controls the flow of oil
Piston rings: A set of rings that seal the cylinder walls, shown in the image.

Types of Bearings

Axial & radial: A type of bearing
Roller / Radial: A type of bearing
Recessed: A type of bearing

Lubrication

Increasing engine volumetric efficiency
Reducing friction
Increasing engine compression ratio
Reducing engine maximum speed
Absorbing heat (reducing engine temperatures)
Cushioning engine parts
Decreasing engine compression ratio
Improving engine mid-range torque
Increasing engine frictional losses
Increasing flight control rate of motion
Cleaning (cleaning/removing debris)
Protecting from corrosion;
Improving planned obsolescence
Accelerating wear and corrosion

Cooling (1)

Trapping air above/below engine raises pressure
Directing the air through engine's cooling system

Cooling (2)

High performance piston aircraft: thermostat, wing flaps, and cowl flaps control engine temperature.
Engine cowl: directs air around the engine for cooling.
Cowl flaps control the amount of air leaving the cowls.

Cooling (3)

Engine uses a single CHT probe in a specific hot cylinder
Horizontal opposed aircraft use oil cooling via cooling fins on cylinder assemblies

Cooling (4)

Instruments for air-cooled engines: CHT (cylinder head temperature), EGT (exhaust gas temperature).
Air-cooled engines use liquid cooling systems or air cooling systems
Liquid Cooling systems are preferred for higher-performance engines.
Components of a liquid cooling system: Reservoir, radiator, thermostat, and water jackets
Percentage of engine cooling from oil is a small amount like 40%

Oil Temperature

Component that controls oil temperature: oil cooler
Component that reduces oil temperature: oil cooler
Mil-L-22851D: ashless dispersant oil used during the break-in period or during hot weather
Mil-L-60823E: straight mineral oil used after break-in period

Suction Screens

Purpose: preventing large particles from damaging the pump
Location: after the oil pump and before the pressure relief valve or filter

Carb Parts

Brass float, Composite float, Plastic float, Boost venturi, Main venturi, Discharge nozzle, Drain plug, Idle mixture screw, Throttle valve, Pump discharge tube, Mixture control, Accelerator pump, Needle valve, Float.

Engine Control (15)

Throttle valve controls air flow
Mixture control: a system relating the mixture of fuel and air in combustion.

Mixture Ratio

Mixture ratio: proportion of fuel to air.
Rich mixture: high fuel-to-air ratio
Lean Mixture: Low fuel-to-air ratio.

Idling Systems

Idle Mixture port: a port located just down stream or above the throttle valve.

Carb Adjustments (21)

Idle speed adjustment: turning the adjustment screw; cold conditions for cold engine adjustment.
Idle adjustment to raise speed: clockwise for hot condition
Idle adjustment to lower speed: counterclockwise when cold.
Float level adjustment: bending the needle valve tab.

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Description

Test your knowledge on the major components of various engine types and their numbering systems. This quiz covers Lycoming and Continental engines, including cylinder placement and key parts such as the crankcase and piston rings. Perfect for aspiring mechanics and automotive enthusiasts.