Reciprocating Engine Ignition System Flashcards
Which of the two types of cams has a uniform distance between cam lobes?
uncompensated
The number of spark plugs legally required for a cylinder
Two
The magnetic poles switch position every
180 degrees
Alnico is comprised of
Aluminium, nickel and cobalt
Condition in which spark of magneto to jump to the wrong electrode
Flash over
The purpose of a secondary ignition coil
Steps up voltage which is needed to create a spark
The components of the magnetic circuit of a magneto
Permanent magnet, pole shoes, coil core
The two types of cams used in current day magneto systems are
compensated cams, uncompensated cams
How a pressurized magneto prevents high altitude flash-over
It’s more difficult for a spark to jump through denser air
The name of the position for when the magnetic poles are aligned with the pole shoes
Full register
The components of the primary circuit in a magneto system
Primary winding, contact breakers and a capacitor
The most commonly used cam in magneto systems
uncompensated cams
The specific number of degrees beyond the neutral point is termed
the efficiency gap
Where flash over is more likely to occur
High altitude
The issue of flash over is more a problem with which type of magneto
high tension
Difference between a battery ignition system and a high tension system in a piston engine
Battery system uses a battery for voltage generation and the high tension uses a permanent magnet generator
Carbon tracking is a consequence of______ _____and happens inside the_____.
flash over, distributor
The name of the position when the magnetic poles have no flux lines through them
Neutral position
The reasons for why the pole shoes are laminated
To reduce eddy currents and cools the magneto
Average number of turns in a primary coil winding of a magneto system
180 turns
The system component which directs stepped-up voltage to the spark plugs
Distributor
The 3 circuits of a magneto system
Magnetic, primary and secondary
Flash over leads to a condition called
carbon tracking
14 CFR Part 33 states that each spark ignition system must have a minimum of
Two spark plugs
Another word for a capacitor
Condenser
The material rotating magnets are constructed of
Alnico
Permalloy is used in the construction of
Permanent magnets
Compensated cams are usually found on which type of piston engine?
radial
At full register position the magnetic field strength is
The strongest
The average amount of turns/ winding in the secondary circuit
13,000
The component in which current flows through, after the secondary winding, and just before reaching the distributor
Spring-loaded carbon brushes
Where the spring-loaded carbon brush is mounted to in a magneto system
center of the distributor
The name of the position in which the breaker points open
E-gap
Current flow through the primary coil is interrupted by
The contact breakers opening
The location where the current jumps the air gap between center and ground electrodes
spark plug
The speed of the distributor rotor in the magneto
half the crankshaft speed
The two factors affecting the speed of rotation of the rotating magnet
- number of poles 2. number of engine cylinders
The formula for magneto shaft speed
Number of cylinders/ 2 x number of poles
The term for the rotational speed necessary for the magneto to fire a spark plug
Coming-in speed
Typical coming-in speed range for a magneto
Between 100 and 200 r.p.m.
The reason why the coming-in speed is insufficient during engine start up
Starter motor cannot crank the crankshaft fast enough
4 types of auxiliary ignition systems used in piston engine aircraft
- Shower of sparks 2. Impulse coupling 3. Booster magneto 4. Induction vibrators
The 3 components of an impulse coupling
- Housing 2. fly weights 3. spring
Function of an Impulse coupling
Intensify and retard the ignition spark at low engine speed to facilitate engine starting
The condition of both magnetos when the cockpit ignition switch is positioned to the OFF position
Both magneto circuits are shorted though the iggntion switch to ground
Any time a tech perfroms maintenance on an ignition system, what should be done with the switch?
Operational check
Steps in an operational check of the magneto
- Run engine between 1500 and 1700 r.p.m.
- Move iggnition switch from BOTH to LEFT (Observe slight rpm drop)
- Move switch back to BOTH
- Move switch from BOTH to RIGHT (Observe slight RPM drop)
- Move switch from RIGHT to BOTH
- Throttle to idle
- Move switch to OFF
An open P-lead on a Magneto system or a faulty igntion switch will be evidenced by
Engine continuing to run with IGNITION Switch in the OFF position
In retaining the magnetism of the rotating magnet of a Magneto, place soft_____ _______ accross the poles
How soft iron keepers are placed
Another word for a Magnetometer
Another word for a gauss meter
The use for a Magnetometer
Machine which test for the strength of a magnet
The part of the entire magneto assembly which is subject to the most wear
Contact breakers
How excessive wear between the Magneto distributor gear teeth is found
place a drill bit inbetween magneto distributor gear teeth
First step in internal timing of a Magneto
Finding the neutral position by rotating the magnet shaft by hand until you feel the magnet pull into alignment
The reason why magneto housing would be vented
Arcing in the magneto cases corrosive gasses,
condensation and water vapor needs to find its way out of the magneto case
What the induction vibrator in a Magneto system does
Provides pulsing direct current (DC) to the primary winding of the magneto coil
The names of the two most commonly used magnetos in gernal aviation
- Bendix Magnetos
- Slick Magnetos
Piror to Magneto installation on an engine, the crankshaft must:
Crank shaft must be positioned with the number 1 piston in firing position
Tools required for engine magneto installation
- Piston stop
- Propeller protractor (Flower pot)
or just a
Time-rite indicator
In preparing the engine for magneto installation, moving the piston backward beyond the ignition timing mark and then foreard to the firing positon ensures compensation for “ Backlash”. What is Backlash
Backlash is lost motion in the gear train due to gaps between the teeth

- Single Magneto
- Dual Magneto

- Distributor Gear
- High output coil
- Impulse coupling
- Magnet
- Pinion gear
- Ball Bearing
- Cam
- Capacitor
- Distributor block
The typical root cause of excessive contact breaker wear
A defective capacitor
The type of voltage used to test a capacitor for electical leakage
DC
The type of voltage used to test a capacitor for capacity
AC
The presence of engine oil in a magneto will indicate failure of
Failure of oil seal in the magneto
The 3 times that the magneto-to-engine timing must be checked
- Overhaul
- 100 hour inspection
- Annual inspection
The 2 sizes of ignition leads used for aircraft magneto systems
- five millimeter
- seven millimeter

Propeller timing indicator
Term for the smallest gear in a gear system
Pinion gear
Identify

- Outter race
- Inner race
The final step in magneto assembly
Internal magneto timing
The procedure for servicing a cracked magneto case
Replace the unit
The differnce between high-tension and low-tension magnetos systems
Low tension magneto systems have transformers at each sprak plug to step up the voltage before spark
High tension systems has the voltage stepped up before the distributor
The greatest amount of magnetic field stress exist when and why?
Just after neutral point because this is when magetic field polarity starts to reverse
(magetic field resist change in direction)
Why do the contact breakers open at E-gap?
They open to colapse the field ASAP, since polarity reverse past neautral position and the magnetic field resist direction change
What does P-lead stand for in a magneto system
Primary lead
If the P-lead in a magneto system breaks what will be the most likely condtion of the engine?
Will be “HOT” and ready to fire with just a small turn of the propeller
What type of shorts can you have in the magneto system leads
Conductor can short to shielding
Conductor can short to airframe or engine