magnetos in aircraft engines are considered live when the engine is running

when it’s grounded

1. Battery Ignition Systems 2. High Tension Magneto Ignition Systems 3. Low Tension Magneto Ignition Systems 4. Electronic Ignition Systems

1. A dual ignition system with at least two spark plugs per cylinder and 2. Two separate sources of electric energy 3. Or have an ignition system of equivalent in-flight reliability

Ignition Switch 1. Battery 2. Ignition Coil 3. Breaker points 4. Cam 5. Capacitor 6. Distributor 7. Spark plugs

less components, less moving parts

Relies on the ship battery. No redundancy Spark intensity depends on battery condition

1. The magneto 2. A wiring harness 3. Set of spark plugs

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1. Enlarged distributer 2. Improved materials with better insulating properties 3. Pressurized magnetos, using a pump or turbocharger. Higher pressure air reduces flashover

1. Flashover During high altitude operation (Can also be caused by moisture in the distributor due temp changes caused by altitude changes 2. Can cause the spark to jump to the wrong electrode in the distributer 3. Often leads to carbon tracking which appears as a fine pencil like carbon trail inside the distributer. 4.Over time carbon tracks can form a conductive path to ground.

the voltage level at which the spark is generated. • High tension magnetos generate a high voltage spark directly at the spark plug, while •low tension magnetos generate a lower voltage that is used to power an external ignition coil to generate the high voltage spark.

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1. A magnetic circuit 2. A primary electrical circuit 3. A secondary electrical circuit *All are controlled by an ignition switch in the cockpit*

Flux flows to the right Flux flows to the left

Flux does not flow through coil core

an electrical discharge that occurs when an electrical current jumps across a gap between two conductive surfaces

requires careful diagnosis and troubleshooting to identify the root cause of the problem. By addressing issues such as dirty spark plugs, incorrect spark plug gaps, or timing problems, you can help to reduce arcing and improve the performance and reliability of your engine.

installed in parrallel

used to help reduce electrical noise, protects from voltage spikes

parrallel

series

efficiency gap

•Primary windings- 180 to 200 turns •Secondary windings- 13,000 turns of fine wire •Ratio is capable of producing a 20,000 volt pulse

The distributor block of a typical magneto ismade of an insulating material with electrodes on one side and receptacles for spark plug on the other.

small carbon brush routes current to the distributor rotor.

It is typically located on the back of the magneto, near the distributor cap.

The P-lead is a safety feature that is designed to prevent the magneto from producing a spark when the ignition switch is in the "off" position

yes

Flashover is an electrical discharge that occurs when a high voltage electrical current jumps across an air gap or other insulation material. It typically occurs when there is a breakdown of the insulating material, which can be caused by factors such as high humidity, contamination, or physical damage.

proper maintenance, using high quality components, use of insulating and grounding materials.

•flange mount •elongated slots •base mount •vernier coupling

Adjust magneto to engine timing by disconnecting the coupling and rotating the rubber disk the necessary number of slots.

•Incorporates two magnetos in one housing. • One rotating magnet and cam are common to two sets of breakers and coils

•Some magnetos are connected to the engine with an anti- vibration coupling. •The engine drives the magneto through a “rubber cushion” housed by a steel retainer attached to the magneto drive gear. The “cushion” reduces the amount of vibration transferred to the magneto

flashover

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•reliable and effiecient •While it may not provide the same high voltage output as the high tension system, it is a proven and effective technology that has been used for many years in the aviation and small engine industries.

limitations, such as lower spark energy and limited flexibility.

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Unison industries developed the first FAA-PMA approved microprocessor- based electronic ignition control system for reciprocating engines

It combines microelectronics with conventional magnetos to provide controllable ignition timing It senses RPM, MAP and CHT

RPM, MAP and CHT

Magnetos, Controller, Wiring harness

Full Authority Digital Engine Control •The ignition system is computer-controlled for ideal operation. Engine sensors provide data to a computer, which determines and controls every ignition event in each cylinder.

Inspect for condition of case •Inspect Breaker points for wear and condition and replace as needed • Inspect Capacitor and replace as needed • Inspect distributor and rotor for cracks, carbon tracks, soot and other signs of arcing. Replace as necessary • As part of a 100 hr insp. Check magneto to engine timing. Adjust as needed.

•After a few hours of operation, metal begins to transfer between the points, leaving a slightly wavy appearance •A mound extending above the surface on a contact indicates excessive wear requiring breaker assy. replacement

•Magnetos are typically sent to the manufacturer or a certified repair facility for overhaul.

Carries high voltage from the distributor to the spark plug with minimal line loss. •Prevent radio noise from the pulsing high voltage pulsing electrical current passing through the wire

it is vulnerable to heat, moisture and the effects of changing altitude. These factors, plus aging insulation and normal gap erosion, work against efficient engine operation.

yes, The insulation may break down on a wire inside the harness and allow the high voltage to leak through the insulation to the harness shielding instead of going to the spark plug.

the plug will not fire

Lead made of either stranded wire or a single coiled conductor (Bendix vs Slick) The leads can be 5mm, 7mm, or 9mm. (5mm most common)

The ¾-20 spark plug is most common

depends, some require bends. sharp bends must be avoided thou

This type of terminal is referred to as “all-weather” because the silicone rubber forms a water-tight seal at the top of the spark plug.

they’re crimped onto the ignition lead

The ignition lead shielding is held tightly between the inner and outer “ferrule” and provides a durable ground connection

high voltage leaks

•an arc forms and burns a path across the insulator where the moisture exists. • If there is a gasoline, oil or grease present, it will break down and form carbon. The burned path is called a carbon track, since it is actually a path of carbon particles.

An increase in manifold pressure increases the compression pressure and resistance of the air across the air gap of the spark plugs

checks the condition or effectiveness of the insulation around each cable in the harness.

Ensures that the ignition lead conductor is intact

The rotational speed necessary for a magneto to fire a spark plug is known as magneto coming-in speed

no

normal ignition timing can cause an engine to kick back “during start”

some magnetos use a set of retard breaker points to delay the spark during engine starting

When a booster magneto generated adequate voltage, the output was sent to a special distributor with a trailing finger that directed a spark to the previous cylinder in the firing order. This resulted in ignition occurring when a piston is on its power stroke.

supplies pulsing direct current (DC) to the primary winding of a magneto coil, inducing current into the secondary winding.

The shower of sparks ignition system is an updated version of the induction vibrator with the same function, except that a set of breaker points retards the ignition timing during engine start.

located in the left magneto with the advance points.

the starting vibrator in a “shower of sparks system” is mounted to the aircraft firewall

very limited maintenance. only removal and replacement

stores electrical energy in a series of capacitors and increases the voltage prior to delivery to the magneto circuit.

Impulse couplings are widely used to augment low speed ignition from magnetos. •The spring-loaded impulse coupling is wound up by the magneto drive gear and then released, providing a momentary increase in rotational speed while delaying the spark.

Stop pin body trigger ramp

flyweights