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Magneto Madness Steve Berube, A&P TakeWING Safety Meeting www.takeWINGInc.com 541-895-5935
Magneto Madness
Steve Berube, A&P
Magneto Madness
Steve Berube, A&P
TakeWING Safety Meeting
www.takeWINGInc.com
541-895-5935
TakeWING Safety Meeting
www.takeWINGInc.com
541-895-5935
The Magic of MagnetosThe Magic of Magnetos
We will discuss (and tell stories about)….
How a magneto works (at a simple level)
How magneto knowledge will make you a safer pilot
Why the P-Lead can kill you
What to look for during run-up
What to do if the engine begins running rough in flight
We will discuss (and tell stories about)….
How a magneto works (at a simple level)
How magneto knowledge will make you a safer pilot
Why the P-Lead can kill you
What to look for during run-up
What to do if the engine begins running rough in flight
Close encounters?Close encounters?
What & when was your first encounter with a magneto?
What & when was your first encounter with a magneto?
Everyday machinesEveryday machines
Lawn mowerChain sawOutboard boat motorWeed eaterLeaf blowerMini-bikeGo-cart
Any small portable gasoline engine uses a magneto.
Lawn mowerChain sawOutboard boat motorWeed eaterLeaf blowerMini-bikeGo-cart
Any small portable gasoline engine uses a magneto.
Magneto MadnessMagneto Madness
Magnet
Magneto
Magnetism
Magnetism fundamentals
Magnet
Magneto
Magnetism
Magnetism fundamentals
Magnetic MadnessMagnetic Madness
Magnetic FieldLines of FluxMagnetic FieldLines of Flux
Magnetic Properties Magnetic Properties
Magnetic Field ConcentrationMagnetic Field Concentration
Magnets and ElectricityMagnets and Electricity
Magnetic Induced Electricity
Wire passing through amagnetic field creates electricity.
ElectromagnetismElectromagnetism
Electromagnetism
Magnetic Field
Electricity flowing through a wire creates a magnetic field.
Magneto MadnessMagneto Madness
Automotive Ignition Systemsput the Magnetos into context.
Automotive Ignition Systemsput the Magnetos into context.
Automotive Ignition SystemAutomotive Ignition System
Battery
12 Volts
Spark PlugsIgnition Wires
Distributor
Coil
Step-upTransformer
(12 Volts to 20,000 Volts)
Rotor
Points
Ignition Switch
Speaking of SparksSpeaking of Sparks
Ignition Coil
(Electromagnetic Induction & Step-up Transformer)
Ignition Coil
(Electromagnetic Induction & Step-up Transformer)
BatterySwitch
Coil
Step-upTransformer
(12 Volts to 20,000 Volts)
PrimaryCoil
SecondaryCoil
200 turns 13,000 turns
12V
20,000V
Ignition SystemsIgnition Systems
Automobile DistributorAutomobile Distributor
Rotor
Points
Ignition systemsIgnition systems
Coil
Distributor
Spark Plug
Coil
Distributor
Spark Plug
Ignition SystemsIgnition Systems
Automotive Ignition SystemAutomotive Ignition System
Battery
12 Volts
Spark PlugsIgnition Wires
Distributor
Coil
Step-upTransformer
(12 Volts to 20,000 Volts)
Rotor
Points
Ignition Switch
Ignition SystemsIgnition Systems
Aircraft Ignition SystemAircraft Ignition SystemMagnetos
Spark Plugs
Ignition Harness
No Battery!!
Ignition Switch
Auto to AirplaneAuto to Airplane
Aircraft EngineAircraft Engine
Aircraft Ignition SystemAircraft Ignition System
Aircraft Ignition SystemAircraft Ignition System
Magneto
Rotor
Coil
Points
Magnet
Distributor
P-Lead
The Magnetreplaces the
Battery
Aircraft Ignition SystemAircraft Ignition System
Aircraft MagnetosAircraft Magnetos
Magneto MadnessMagneto Madness
Magneto MadnessMagneto Madness
Magnetic CircuitMagnetic CircuitCoil
MagnetIron
Pole Shoes
Rotating Magnet MagnetoRotating Magnet Magneto
Magneto MadnessMagneto Madness
Rotating Magnet MagnetoRotating Magnet Magneto
Magneto MadnessMagneto Madness
Magneto Ignition SystemMagneto Ignition System
& MAGNET
& MAGNET
Ignition Switch
On
P-Lead
PrimaryWinding
SecondaryWinding
Aircraft Ignition SystemAircraft Ignition System
Spark Plugs
Magnetos Ignition Harness
No Battery!!
MagnetosMagnetos
• The ignition system is completely independent of the aircraft electrical system.
– If the aircraft electrical system were to fail the engine would continue to run!
• A spinning magnet induces current in the primary coil. This current creates an electromagnetic field around the primary coil. The current is interrupted by a set of breaker points, causing the primary coil magnetic field to collapse. The collapsing field induces current in the secondary coil which generates a high voltage spark. The spark is directed through the distributor via the rotor to the proper spark plug.
• The ignition system is completely independent of the aircraft electrical system.
– If the aircraft electrical system were to fail the engine would continue to run!
• A spinning magnet induces current in the primary coil. This current creates an electromagnetic field around the primary coil. The current is interrupted by a set of breaker points, causing the primary coil magnetic field to collapse. The collapsing field induces current in the secondary coil which generates a high voltage spark. The spark is directed through the distributor via the rotor to the proper spark plug.
Rotating Magnet—MagnetoRotating Magnet—Magneto
• Aids To Starting
• Magnetos provide a good, hot spark at idle, at cruise, and at high speed.
• But not when the engine is turning slowly during start.
» Impulse Coupling
• Aids To Starting
• Magnetos provide a good, hot spark at idle, at cruise, and at high speed.
• But not when the engine is turning slowly during start.
» Impulse Coupling
Provides momentary high rotation speed and a retarded spark for engine startingProvides momentary high rotation speed and a retarded spark for engine starting
Impulse Coupling
Impulse CouplingImpulse Coupling
Impulse couplingRetarded SparkImpulse couplingRetarded Spark
Intake Compression Power Exhaust
BTDC ATDC
Inside the Impulse CouplingInside the Impulse Coupling
Body
Coil Spring
Flyweight Cam
Impulse CouplingImpulse Coupling
OK, so what does all this magneto stuff mean to the pilot?OK, so what does all this magneto stuff mean to the pilot?
Magneto MadnessMagneto Madness
Understanding Your ChecklistsUnderstanding Your Checklists
• P-Lead ground (pre-flight)– During pre-flight always spin the prop backwards
(except Rotax 912)!– Broken P-lead, poorly grounded P-Lead, or faulty
ignition switch will leave the magneto HOT!
• Run-up /Before Takeoff Checks– Magneto Safety Check (ignition switch test)
• Idle RPM, turn ignition switch from “both” to “off”• Listen for complete cutting off of the engine• Engine cut off indicates proper P-lead connection and
ignition switch operation
• P-Lead ground (pre-flight)– During pre-flight always spin the prop backwards
(except Rotax 912)!– Broken P-lead, poorly grounded P-Lead, or faulty
ignition switch will leave the magneto HOT!
• Run-up /Before Takeoff Checks– Magneto Safety Check (ignition switch test)
• Idle RPM, turn ignition switch from “both” to “off”• Listen for complete cutting off of the engine• Engine cut off indicates proper P-lead connection and
ignition switch operation
Ignition System Operational Ignition System Operational
Magneto Safety Check (con’t)Run-upMagneto Safety Check (con’t)Run-up
“Both” to “Right” and “Both” to “Left” — what should the Tachometer do? Here’s what five POHs said.
“Both” to “Right” and “Both” to “Left” — what should the Tachometer do? Here’s what five POHs said.
Notice the RPM between left and right magnetos, the difference between the magnetos should not exceed 50 RPMNotice the RPM between left and right magnetos, the difference between the magnetos should not exceed 50 RPM
A slight RPM drop approximately the same on each magneto. Regardless of the drop, the engine should run smoothly.
A slight RPM drop approximately the same on each magneto. Regardless of the drop, the engine should run smoothly.
1. 100 RPM drop max.
2. RPM drop should not exceed 125 RPM on either magneto or 50 RPM
differential between magnetos.
3. Drop off on either magneto should not exceed 175 RPM.
4. The difference between the magnetos should not exceed 50RPM.
5. 200 RPM maximum drop, 50 RPM maximum differential
Magneto Checks (con’t)Magneto Checks (con’t)
• Run-up checks (con’t)– Magneto Operation Check
• Rapid RPM drop or rough engine may indicate a fouled spark plug or faulty ignition harness
• Slow RPM drop is usually caused by improper timing or valve adjustment
• Excessive RPM differential between the mags indicates a difference in timing between the left and right magnetos.
• Absence of RPM drop indicates a defective P-lead ground connection
• If the engine is rough regardless of the magneto setting then the problem may not be ignition, but an air intake leak or valve train problem instead.
• Run-up checks (con’t)– Magneto Operation Check
• Rapid RPM drop or rough engine may indicate a fouled spark plug or faulty ignition harness
• Slow RPM drop is usually caused by improper timing or valve adjustment
• Excessive RPM differential between the mags indicates a difference in timing between the left and right magnetos.
• Absence of RPM drop indicates a defective P-lead ground connection
• If the engine is rough regardless of the magneto setting then the problem may not be ignition, but an air intake leak or valve train problem instead.
Common Causes of Engine Roughness—Before TakeoffCommon Causes of Engine Roughness—Before Takeoff
– Spark plug fouling• A slight engine roughness found before flight
may be caused by one or more spark plugs becoming fouled by carbon or lead deposits.
• This may be discovered by turning the ignition switch momentarily from BOTH to either L or R position to determine if one mag is “rougher” (greater than expected RPM drop) than the other.
• Assuming that spark plugs are the more likely cause, increase RPM then lean the mixture to the recommended lean setting. Enrich the mixture again and retest. If the problem does not clear up within one or two attempts to clear the spark return the aircraft to the school for maintenance.
– Spark plug fouling• A slight engine roughness found before flight
may be caused by one or more spark plugs becoming fouled by carbon or lead deposits.
• This may be discovered by turning the ignition switch momentarily from BOTH to either L or R position to determine if one mag is “rougher” (greater than expected RPM drop) than the other.
• Assuming that spark plugs are the more likely cause, increase RPM then lean the mixture to the recommended lean setting. Enrich the mixture again and retest. If the problem does not clear up within one or two attempts to clear the spark return the aircraft to the school for maintenance.
Causes of In-Flight Engine RoughnessCauses of In-Flight Engine Roughness
– Magneto malfunction• A sudden engine roughness or misfiring is
usually evidence of magneto problems. Switching from BOTH to either L or R ignition switch position will identify which magneto is malfunctioning. Select different power settings and enrich the mixture to determine if continued operation on BOTH magnetos is practicable. If not, switch to the good magneto and proceed to the nearest airport for repairs.
– Magneto malfunction• A sudden engine roughness or misfiring is
usually evidence of magneto problems. Switching from BOTH to either L or R ignition switch position will identify which magneto is malfunctioning. Select different power settings and enrich the mixture to determine if continued operation on BOTH magnetos is practicable. If not, switch to the good magneto and proceed to the nearest airport for repairs.
Magneto Madness
Thank you!
Magneto Madness
Thank you!
TakeWING Safety Meeting
www.takeWINGInc.com
541-895-5935
TakeWING Aviation Club and Maintenance Center
TakeWING Safety Meeting
www.takeWINGInc.com
541-895-5935
TakeWING Aviation Club and Maintenance Center
