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Problems With The Fuel System Detonation: • Very rapid and violent burning of the fuel in the cylinder. • Causes overheating and damage to the metal of the engine. • Signs: • rapid rise in cylinder pressure, and • rapid increase in cylinder head temperature.

Problems With The Fuel System • Causes: • incorrect fuel, • overheating (lack of airflow), and • the setting a mixture that is too lean. • Can be solved temporarily by making the mixture richer and permanently by using fuel of the octane rating specified by the engine manufacturer.

Problems With The Fuel System Pre-Ignition: • Premature burning of fuel mixture due to glowing carbon particles or “local hotspots”. • Often confused with detonation. • Experienced when attempting to start a hot engine and usually results in a backfire. • Can do severe damage including warped pistons, and cracked cylinder heads.

Problems With The Fuel System • Occurs in the fuel line. • Caused by high atmospheric temperatures, causing the fuel to vaporize and block the flow of liquid fuel in the line. Vapour Lock:

Ignition System • The function of the ignition system is to supply a spark to ignite the fuel/air mixture in the cylinders. • It consists of: • two magnetos, • two spark plugs per cylinder, • ignition leads, and • a magneto switch.

The Magneto • If a coil of wire is rotated in a magnetic field, current will be induced in the coil. • This experiment demonstrates the inseparability of magnetism and electricity. • While the design of the magneto is slightly different from that discussed above, the principle is the same.

The Magneto • Serves three functions: • generates a low tension current, • transforms this to a high tension, and • distributes the current to the individual spark plugs at the exact time it is desired to have them fire.

Confirmation Stage NOTE: You must use the buttons in the Confirmation Stage

Aero Engines Fuel problems, Ignition, and Basic Electrical System Let's try a few review questions on Aero Engines: Question #1 - What does the magneto do? Generates a low tension current A B Prevents overheating C Connects distributor to spark plug D None of the above

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Aero Engines Fuel problems, Ignition, and Basic Electrical System Let's try a few review questions on Aero Engines: Question #2 - Name a cause of detonation? Too rich a mixture A B Too lean a mixture C Incorrect oil D Both A and B

Dual Ignition • Modern aero engines are fitted with two spark plugs per cylinder and two magnetos. • One magneto fires one of the spark plugs for each cylinder, while the second magneto fires the second spark plug for each cylinder. • Purpose is two fold: • safety: if one system fails, the engine will still operate, and • performance: improves combustion

Magneto Switch • The magneto switch has four settings: • left, • right, • both, and • off. • To check magnetos, pilot watches RPMs as he/she turns switch. • In the event of rough operation, the pilot can switch to the smoothest operating magneto.

Shielding • The parts of the ignition system are surrounded with metal covering which is grounded. • This design is known as shielding and is used to prevent interference with the radio.

Ignition Timing • The timing of the magneto to fire the spark plug at the proper time. • Firing too early can result: • in loss of power, • pre-ignition, • piston burning, • scored cylinders, and • broken rings.

Aero Engines Fuel problems, Ignition, and Basic Electrical System Let's try a few review questions on Aero Engines: Question #3 - What is the purpose of dual ignition? Safety A B Longer engine life C Prevent overheating D Both A and C

Aero Engines Fuel problems, Ignition, and Basic Electrical System Let's try a few review questions on Aero Engines: Question #4 - What is shielding? Improves combustion A B Surrounds cockpit C Fire wall D Metal covering

Supplies power to start the airplane. Also required to operate a multitude of controls including: flaps, undercarriage, all radios, lights, etc. Includes everything that operates electrically, except the magnetos. The ignition system is not connected with the airplane’s electrical system. Electrical System

Components • Storage Battery: • stores electrical energy required for engine starts. • Master Switch: • overall on/off switch for the electrical system. • Starter Motor: • turns the engine over after it receives current from the battery.

Components • Generator/Alternator: • supplies current to the system and recharges the battery, • driven by the engine, • once motor is started, the alternator will take over and transfer the energy. • Voltage Regulator: • prevents the system from being overloaded and the battery from overcharging.

Components • Bus Bar: • receives from the battery and the generator (or alternator) and distributes it to various circuits. • Circuit Breakers: • prevents component damage resulting from system overloads. • Ammeter/Voltmeter: • indicates current and voltage storage and drain of the system.

Components • Generator Warning Light: • indicates only of generator failure, and • aircraft without ammeter/voltmeters have this.

Aero Engines Fuel problems, Ignition, and Basic Electrical System Let's try a few review questions on Aero Engines: Question #5 - What prevents component damage resulting from system overloads? Bus bar A B Voltage regulator C Circuit breaker D Ammeter

Aero Engines Fuel problems, Ignition, and Basic Electrical System Let's try a few review questions on Aero Engines: Question #6 - What stores electrical energy for engine starts? Battery A B Alternator C Bus bar D Ammeter

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