Fill in the Blanks
1. An 18-cylinder radial engine using a low-tension magneto ignition system will have __________ high-tension transformers.2. The pole shoes in a magneto are made of ______________________________.
3. The greatest change in the number of lines of magnetic flux in the coil core takes place when the magnet is in its __________________ position.
4. Because of the magnetic field produced by the primary current, the greatest change in the total magnetic flux occurs _____________ the magnet passes its neutral position.
5. The breaker points in a magneto are closed when the rotating magnet is in its _________________ position.
6. The point at which the breaker points open is called the _____________ angle.
7. The vast majority of four- and six-cylinder horizontally opposed engines use a/an _______________________ (what system) to produce a hot and late spark for starting.
8. The Bendix __________________________ (what system) is a modern version of the induction vibrator.
9. The extra set of breaker points used with the “shower of sparks” system are referred to as the _______________ points.
10. On an engine equipped with the “shower of sparks” system, the _________ magneto is of standard construction.
11. You can be sure that the breaker points will close at the correct position of the rotating magnet if their _______________________________ is correct.
12. Magneto-to-engine timing is accomplished using the firing position of cylinder number _________ as the reference.
13. A _________________________ is used to show exactly the time at which the breaker points open.
14. Close timing of a base-mounted magneto to an aircraft engine is permitted by using a ______________________________.
15. The engine analyzer is an adaptation of the laboratory ________________________.
2. A magneto is actually a self-contained alternating current generator.TRUE/FALSE
3. Currently manufactured, certificated, reciprocating engines will use the low-tension magneto ignition. TRUE/FALSE
4. When the magnet is in its full-register position, the maximum number of lines of magnetic flux are passing through the coil core. TRUE/FALSE
5. The magnetic field produced by current flowing in the primary coil aids the magnetic field that caused it to flow. TRUE/FALSE
6. The high-tension magneto uses a separate distributor. TRUE/FALSE
7. The distributor in a magneto is in the secondary electrical circuit. TRUE/FALSE
8. Magnetos have the problem of not producing a hot enough spark when they turn too slow. TRUE/FALSE
9. An engine equipped with the “shower of sparks” system will use only the left magneto for starting. TRUE/FALSE
10. The impulse coupling should be engaged when timing the magneto to the engine. TRUE/FALSE
11. Wear of the breaker points will cause the timing of a magneto to drift late. TRUE/FALSE
12. The capacitance caused by shielding of the ignition leads causes excessive electrode erosion around the ignition leads. TRUE/FALSE
13. A spark plug that has a long nose core insulator (heat path) is a cold spark plug. TRUE/FALSE
14. An engine operating with a too lean idle mixture will cause the spark plugs to have black sooty deposits in their firing end cavity. TRUE/FALSE
15. Lead fouling may occur on a spark plug that is too cold for the engine operating conditions. TRUE/FALSE
__________________________________________________
2. What is the function of the capacitor in a magneto?
__________________________________________________
3. What is a compensated magneto cam, and on what kind of engine is one used?
__________________________________________________
4. What is the significance of the numbers on the distributor of an aircraft magneto?
__________________________________________________
5. What happens in a magneto ignition system when the ignition switch is placed in the Off position?
__________________________________________________
6. What is the reason for having a low-tension ignition system on some aircraft?
__________________________________________________
7. What is the basic difference between a low-tension magneto and a high-tension magneto?
__________________________________________________
8. What is meant by an All Weather spark plug?
__________________________________________________
9. What is meant by the reach of a spark plug?
__________________________________________________
11. You can be sure that the breaker points will close at the correct position of the rotating magnet if their _______________________________ is correct.
12. Magneto-to-engine timing is accomplished using the firing position of cylinder number _________ as the reference.
13. A _________________________ is used to show exactly the time at which the breaker points open.
14. Close timing of a base-mounted magneto to an aircraft engine is permitted by using a ______________________________.
15. The engine analyzer is an adaptation of the laboratory ________________________.
True or False
1. Aircraft engines are required to have dual ignition. TRUE/FALSE2. A magneto is actually a self-contained alternating current generator.TRUE/FALSE
3. Currently manufactured, certificated, reciprocating engines will use the low-tension magneto ignition. TRUE/FALSE
4. When the magnet is in its full-register position, the maximum number of lines of magnetic flux are passing through the coil core. TRUE/FALSE
5. The magnetic field produced by current flowing in the primary coil aids the magnetic field that caused it to flow. TRUE/FALSE
6. The high-tension magneto uses a separate distributor. TRUE/FALSE
7. The distributor in a magneto is in the secondary electrical circuit. TRUE/FALSE
8. Magnetos have the problem of not producing a hot enough spark when they turn too slow. TRUE/FALSE
9. An engine equipped with the “shower of sparks” system will use only the left magneto for starting. TRUE/FALSE
10. The impulse coupling should be engaged when timing the magneto to the engine. TRUE/FALSE
11. Wear of the breaker points will cause the timing of a magneto to drift late. TRUE/FALSE
12. The capacitance caused by shielding of the ignition leads causes excessive electrode erosion around the ignition leads. TRUE/FALSE
13. A spark plug that has a long nose core insulator (heat path) is a cold spark plug. TRUE/FALSE
14. An engine operating with a too lean idle mixture will cause the spark plugs to have black sooty deposits in their firing end cavity. TRUE/FALSE
15. Lead fouling may occur on a spark plug that is too cold for the engine operating conditions. TRUE/FALSE
Knowledge Application Questions
1. What is the main advantage of a magneto ignition system over a battery ignition system for an aircraft reciprocating engine?__________________________________________________
2. What is the function of the capacitor in a magneto?
__________________________________________________
3. What is a compensated magneto cam, and on what kind of engine is one used?
__________________________________________________
4. What is the significance of the numbers on the distributor of an aircraft magneto?
__________________________________________________
5. What happens in a magneto ignition system when the ignition switch is placed in the Off position?
__________________________________________________
6. What is the reason for having a low-tension ignition system on some aircraft?
__________________________________________________
7. What is the basic difference between a low-tension magneto and a high-tension magneto?
__________________________________________________
8. What is meant by an All Weather spark plug?
__________________________________________________
9. What is meant by the reach of a spark plug?
__________________________________________________
10. What is the difference between a hot spark plug and a cold spark plug?
__________________________________________________
11. What is checked when a magneto is internally timed?
__________________________________________________
12. What is the purpose of a vernier coupling used on some aircraft magneto drives?
__________________________________________________
13. What is the advantage of fine-wire spark plugs over massive electrode spark plugs?
__________________________________________________
14. Why is it important that the spark plugs be kept in numbered holes in a tray when they are removed from an engine?
__________________________________________________
15. What is the purpose of staggered timing between the two magnetos on an aircraft engine? ___________________________________________________
a. hard steel.
b. soft iron.
c. electrical steel.
2. How is the strength of a magneto magnet checked?
a. Hold the points open and check the output of the primary coil with an AC ammeter while operating the magneto at a specified speed.
b. Check the AC voltage reading at the breaker points.
c. Check the output of the secondary coil with an AC ammeter while operating the magneto at a \ specified speed.
3. The E-gap angle is usually defined as the number of degrees between the neutral position of the rotating magnet and the position
a. where the contact points close.
b. where the contact points open.
c. of greatest magnetic flux density.
4. The greatest density of flux lines in the magnetic circuit of a rotating magnet-type magneto occurs when the magnet is in what position?
a. Full alignment with the field shoe faces.
b. A certain angular displacement beyond the neutral position, referred to as E-gap angle or position.
c. The position where the contact points open.
5. Magneto breaker point opening relative to the position of the rotating magnet and distributor rotor (internal timing) can be set most accurately
a. during the magneto-to-engine timing operation.
b. during assembly of the magneto before installation on the engine.
c. by setting the points roughly at the required clearance before installing the magneto and then making the fine breaker point adjustment after installation to compensate for wear in the magneto drive train.
6. Why are high-tension ignition cables frequently routed from the distributors to the spark plugs in flexible metallic conduits?
a. To eliminate high altitude flashover.
b. To reduce the formation of corona and nitric oxide on the cable insulation.
c. To reduce the effect of the high-frequency electromagnetic waves emanated during operation.
7. What will be the results of increasing the gap of the breaker points in a magneto?
a. Retard the spark and increase its intensity.
b. Advance the spark and decrease its intensity.
c. Retard the spark and decrease its intensity.
8. What is the purpose of a safety gap in some magnetos?
a. To discharge the secondary coil’s voltage if an open occurs in the secondary circuit.
b. To ground the magneto when the ignition switch is off.
c. To prevent flashover in the distributor.
9. When timing a magneto internally, the alignment of the timing marks indicates that the
a. breaker points are just closing.
b. magnets are in the neutral position.
c. magnets are in the E-gap position.
10. When internally timing a magneto, the breaker points begin to open when the rotating magnet is
a. fully aligned with the pole shoes.
b. a few degrees past full alignment with the pole shoes.
c. a few degrees past the neutral position.
11. Magneto timing drift is caused by erosion of the breaker points and
a. excessive spark plug gap.
b. wear of the cam followers.
c. loss of magnetism in the rotor.
12. What is the electrical location of the primary capacitor in a high-tension magneto?
a. In parallel with the breaker points.
b. In series with the breaker points.
c. In series with the primary and secondary winding.
13. In a high-tension ignition system, the current in the magneto secondary winding is
a. conducted from the primary winding via the discharge of the capacitor.
b. induced when the primary circuit is interrupted.
c. induced when the primary circuit discharges via the breaker points.
14. When a “Shower of Sparks” ignition system is activated at an engine start, a spark plug fires
a. as soon as the advance breaker points open.
b. only while both the retard and advance breaker points are closed.
c. only while both the retard and advance breaker points are open.
15. What is the radial location of the two north poles of a four-pole rotating magnet in a high-tension magneto?
a. 180° apart.
b. 270° apart.
c. 90° apart.
16. Magneto pole shoes are generally made of
a. laminations of high-grade soft iron.
b. laminations of high-grade Alnico.
c. pieces of high-carbon iron.
17. Capacitance afterfiring in most modern spark plugs is reduced by the use of
a. fine wire electrodes.
b. a built-in resistor in each plug.
c. aluminum oxide insulation.
18. What components make up the magnetic system of a magneto?
a. Pole shoes, the pole shoe extensions, and the primary coil.
b. Primary and secondary coils.
c. Rotating magnet, the pole shoes, the pole shoe extensions, and the coil core.
19. In an aircraft ignition system, one of the functions of the capacitor is to
a. regulate the flow of current between the primary and secondary coil.
b. facilitate a more rapid collapse of the magnetic field in the primary coil.
c. stop the flow of magnetic lines of force when the points open.
20. When will the voltage in the secondary winding of a magneto, installed on a normally operating engine, be at its highest value?
a. Just prior to spark plug firing.
b. Toward the latter part of the spark duration when the flame front reaches its maximum velocity.
c. Immediately after the breaker points close.
21. When the switch is off in a battery ignition system, the primary circuit is
a. grounded.
b. opened.
c. shorted.
22. As an aircraft engine’s speed is increased, the voltage induced in the primary coil of the magneto
a. remains constant.
b. increases.
c. varies with the setting of the voltage regulator.
23. When internally timing a magneto, the breaker points begin to open when
a. the piston has just passed TDC at the end of the compression stroke.
b. the magnet poles are a few degrees beyond the neutral position.
c. the magnet poles are fully aligned with the pole shoes.
24. The purpose of a safety gap in a magneto is to
a. prevent burning out the primary winding.
b. protect the high-voltage winding from damage.
c. prevent burning of contact points.
25. A defective primary capacitor in a magneto is indicated by
a. a fine-grained frosted appearance of the breaker points.
b. burned and pitted breaker points.
c. a weak spark.
26. How many secondary coils are required in a low-tension ignition system on an 18-cylinder engine?
a. 36.
b. 18.
c. 9.
27. A magneto ignition switch is connected
a. in series with the breaker points.
b. parallel to the breaker points.
c. in series with the primary capacitor and parallel to the breaker points.
28. The spark is produced in a magneto ignition system when the breaker points are
a. fully open.
b. beginning to open.
c. fully closed.
29. Shielding is used on spark plug and ignition wires to
a. protect the wires from short circuits as a result of chafing or rubbing.
b. prevent outside electromagnetic emissions from disrupting the operation of the ignition system.
c. prevent interference with radio reception.
30. What is the purpose of using an impulse coupling with a magneto?
a. To absorb impulse vibrations between the magneto and the engine.
b. To compensate for backlash in the magneto and the engine gears.
c. To produce a momentary high rotational speed of the magneto.
31. The purpose of staggered ignition is to compensate for
a. short ignition harness.
b. rich fuel/air mixture around exhaust valve.
c. diluted fuel/air mixture around exhaust valve.
32. Aircraft magneto housings are usually ventilated in order to
a. prevent the entrance of outside air which may contain moisture.
b. allow heated air from the accessory compartment to keep the internal parts of the magneto dry.
c. provide cooling and remove
33. Failure of an engine to cease firing after turning the magneto switch off is an indication of
a. an open high tension lead.
b. an open P-lead to ground.
c. a grounded magneto switch.
34. Alignment of the marks provided for internal timing of a magneto indicates that the
a. breaker points are just beginning to close for No. 1 cylinder.
b. magneto is in E-gap position.
c. No. 1 cylinder is on TDC of compression stroke.
35. When using a timing light to time a magneto to an aircraft engine, the magneto switch should be placed in the
a. BOTH position.
b. OFF position.
c. LEFT or RIGHT position (either one).
36. What is the difference between a low-tension and a high-tension engine ignition system?
a. A low-tension system produces relatively low voltage at the spark plug as compared to a high-tension system.
b. A high-tension system is designed for high-altitude aircraft, while a low-tension system is for low-to medium-altitude aircraft.
c. A low-tension system uses a transformer coil near the spark plugs to boost voltage, while the high-tension system voltage is constant from the magneto to the spark plugs.
37. What test instrument could be used to test an ignition harness for suspected leakage?
a. A high tension lead tester.
b. A high voltage DC voltmeter.
c. A high amperage DC ammeter.
38. The amount of voltage generated in any magneto secondary coil is determined by the number of windings and by the
a. rate of buildup of the magnetic field around the primary coil.
b. rate of collapse of the magnetic field around the primary coil.
c. amount of charge released by the capacitor.
39. Magneto breaker points must be timed to open when the
a. rotating magnet is positioned a few degrees before neutral.
b. greatest magnetic field stress exists in the magnetic circuit.
c. rotating magnet is in the full register position.
40. In reference to a “Shower of Sparks” ignition system,
(1) the retard breaker points are designed to keep the affected ignition system operating if the advance breaker points should fail during normal engine operation (after start).
(2) the timed opening of the retard breaker points is designed to prevent engine “kickback” during start.
Regarding the above statements,
a. only No. 1 is true.
b. only No. 2 is true.
c. both No. 1 and No. 2 are true.
REFERENCES
__________________________________________________
11. What is checked when a magneto is internally timed?
__________________________________________________
12. What is the purpose of a vernier coupling used on some aircraft magneto drives?
__________________________________________________
13. What is the advantage of fine-wire spark plugs over massive electrode spark plugs?
__________________________________________________
14. Why is it important that the spark plugs be kept in numbered holes in a tray when they are removed from an engine?
__________________________________________________
15. What is the purpose of staggered timing between the two magnetos on an aircraft engine? ___________________________________________________
Multiple Choices Questions
1. The magnetic circuit of a magneto consists of a permanent multi-pole rotating magnet. The core is made ofa. hard steel.
b. soft iron.
c. electrical steel.
2. How is the strength of a magneto magnet checked?
a. Hold the points open and check the output of the primary coil with an AC ammeter while operating the magneto at a specified speed.
b. Check the AC voltage reading at the breaker points.
c. Check the output of the secondary coil with an AC ammeter while operating the magneto at a \ specified speed.
3. The E-gap angle is usually defined as the number of degrees between the neutral position of the rotating magnet and the position
a. where the contact points close.
b. where the contact points open.
c. of greatest magnetic flux density.
4. The greatest density of flux lines in the magnetic circuit of a rotating magnet-type magneto occurs when the magnet is in what position?
a. Full alignment with the field shoe faces.
b. A certain angular displacement beyond the neutral position, referred to as E-gap angle or position.
c. The position where the contact points open.
5. Magneto breaker point opening relative to the position of the rotating magnet and distributor rotor (internal timing) can be set most accurately
a. during the magneto-to-engine timing operation.
b. during assembly of the magneto before installation on the engine.
c. by setting the points roughly at the required clearance before installing the magneto and then making the fine breaker point adjustment after installation to compensate for wear in the magneto drive train.
6. Why are high-tension ignition cables frequently routed from the distributors to the spark plugs in flexible metallic conduits?
a. To eliminate high altitude flashover.
b. To reduce the formation of corona and nitric oxide on the cable insulation.
c. To reduce the effect of the high-frequency electromagnetic waves emanated during operation.
7. What will be the results of increasing the gap of the breaker points in a magneto?
a. Retard the spark and increase its intensity.
b. Advance the spark and decrease its intensity.
c. Retard the spark and decrease its intensity.
8. What is the purpose of a safety gap in some magnetos?
a. To discharge the secondary coil’s voltage if an open occurs in the secondary circuit.
b. To ground the magneto when the ignition switch is off.
c. To prevent flashover in the distributor.
9. When timing a magneto internally, the alignment of the timing marks indicates that the
a. breaker points are just closing.
b. magnets are in the neutral position.
c. magnets are in the E-gap position.
10. When internally timing a magneto, the breaker points begin to open when the rotating magnet is
a. fully aligned with the pole shoes.
b. a few degrees past full alignment with the pole shoes.
c. a few degrees past the neutral position.
11. Magneto timing drift is caused by erosion of the breaker points and
a. excessive spark plug gap.
b. wear of the cam followers.
c. loss of magnetism in the rotor.
12. What is the electrical location of the primary capacitor in a high-tension magneto?
a. In parallel with the breaker points.
b. In series with the breaker points.
c. In series with the primary and secondary winding.
13. In a high-tension ignition system, the current in the magneto secondary winding is
a. conducted from the primary winding via the discharge of the capacitor.
b. induced when the primary circuit is interrupted.
c. induced when the primary circuit discharges via the breaker points.
14. When a “Shower of Sparks” ignition system is activated at an engine start, a spark plug fires
a. as soon as the advance breaker points open.
b. only while both the retard and advance breaker points are closed.
c. only while both the retard and advance breaker points are open.
15. What is the radial location of the two north poles of a four-pole rotating magnet in a high-tension magneto?
a. 180° apart.
b. 270° apart.
c. 90° apart.
16. Magneto pole shoes are generally made of
a. laminations of high-grade soft iron.
b. laminations of high-grade Alnico.
c. pieces of high-carbon iron.
17. Capacitance afterfiring in most modern spark plugs is reduced by the use of
a. fine wire electrodes.
b. a built-in resistor in each plug.
c. aluminum oxide insulation.
18. What components make up the magnetic system of a magneto?
a. Pole shoes, the pole shoe extensions, and the primary coil.
b. Primary and secondary coils.
c. Rotating magnet, the pole shoes, the pole shoe extensions, and the coil core.
19. In an aircraft ignition system, one of the functions of the capacitor is to
a. regulate the flow of current between the primary and secondary coil.
b. facilitate a more rapid collapse of the magnetic field in the primary coil.
c. stop the flow of magnetic lines of force when the points open.
20. When will the voltage in the secondary winding of a magneto, installed on a normally operating engine, be at its highest value?
a. Just prior to spark plug firing.
b. Toward the latter part of the spark duration when the flame front reaches its maximum velocity.
c. Immediately after the breaker points close.
21. When the switch is off in a battery ignition system, the primary circuit is
a. grounded.
b. opened.
c. shorted.
22. As an aircraft engine’s speed is increased, the voltage induced in the primary coil of the magneto
a. remains constant.
b. increases.
c. varies with the setting of the voltage regulator.
23. When internally timing a magneto, the breaker points begin to open when
a. the piston has just passed TDC at the end of the compression stroke.
b. the magnet poles are a few degrees beyond the neutral position.
c. the magnet poles are fully aligned with the pole shoes.
24. The purpose of a safety gap in a magneto is to
a. prevent burning out the primary winding.
b. protect the high-voltage winding from damage.
c. prevent burning of contact points.
25. A defective primary capacitor in a magneto is indicated by
a. a fine-grained frosted appearance of the breaker points.
b. burned and pitted breaker points.
c. a weak spark.
26. How many secondary coils are required in a low-tension ignition system on an 18-cylinder engine?
a. 36.
b. 18.
c. 9.
27. A magneto ignition switch is connected
a. in series with the breaker points.
b. parallel to the breaker points.
c. in series with the primary capacitor and parallel to the breaker points.
28. The spark is produced in a magneto ignition system when the breaker points are
a. fully open.
b. beginning to open.
c. fully closed.
29. Shielding is used on spark plug and ignition wires to
a. protect the wires from short circuits as a result of chafing or rubbing.
b. prevent outside electromagnetic emissions from disrupting the operation of the ignition system.
c. prevent interference with radio reception.
30. What is the purpose of using an impulse coupling with a magneto?
a. To absorb impulse vibrations between the magneto and the engine.
b. To compensate for backlash in the magneto and the engine gears.
c. To produce a momentary high rotational speed of the magneto.
31. The purpose of staggered ignition is to compensate for
a. short ignition harness.
b. rich fuel/air mixture around exhaust valve.
c. diluted fuel/air mixture around exhaust valve.
32. Aircraft magneto housings are usually ventilated in order to
a. prevent the entrance of outside air which may contain moisture.
b. allow heated air from the accessory compartment to keep the internal parts of the magneto dry.
c. provide cooling and remove
33. Failure of an engine to cease firing after turning the magneto switch off is an indication of
a. an open high tension lead.
b. an open P-lead to ground.
c. a grounded magneto switch.
34. Alignment of the marks provided for internal timing of a magneto indicates that the
a. breaker points are just beginning to close for No. 1 cylinder.
b. magneto is in E-gap position.
c. No. 1 cylinder is on TDC of compression stroke.
35. When using a timing light to time a magneto to an aircraft engine, the magneto switch should be placed in the
a. BOTH position.
b. OFF position.
c. LEFT or RIGHT position (either one).
36. What is the difference between a low-tension and a high-tension engine ignition system?
a. A low-tension system produces relatively low voltage at the spark plug as compared to a high-tension system.
b. A high-tension system is designed for high-altitude aircraft, while a low-tension system is for low-to medium-altitude aircraft.
c. A low-tension system uses a transformer coil near the spark plugs to boost voltage, while the high-tension system voltage is constant from the magneto to the spark plugs.
37. What test instrument could be used to test an ignition harness for suspected leakage?
a. A high tension lead tester.
b. A high voltage DC voltmeter.
c. A high amperage DC ammeter.
38. The amount of voltage generated in any magneto secondary coil is determined by the number of windings and by the
a. rate of buildup of the magnetic field around the primary coil.
b. rate of collapse of the magnetic field around the primary coil.
c. amount of charge released by the capacitor.
39. Magneto breaker points must be timed to open when the
a. rotating magnet is positioned a few degrees before neutral.
b. greatest magnetic field stress exists in the magnetic circuit.
c. rotating magnet is in the full register position.
40. In reference to a “Shower of Sparks” ignition system,
(1) the retard breaker points are designed to keep the affected ignition system operating if the advance breaker points should fail during normal engine operation (after start).
(2) the timed opening of the retard breaker points is designed to prevent engine “kickback” during start.
Regarding the above statements,
a. only No. 1 is true.
b. only No. 2 is true.
c. both No. 1 and No. 2 are true.
 |
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- Engine Ignition and Electrical Systems
- Reciprocating Engine Ignition Systems
- Magneto-Ignition System Operating Principles
- FADEC System Description
- Auxiliary Ignition Units
- Spark Plugs
- Reciprocating Engine Ignition System Maintenance and Inspection
- Magneto-Ignition Timing Devices
- Checking the Internal Timing of a Magneto
- Spark Plug Inspection and Maintenance
- Turbine Engine Ignition Systems
- Turbine Ignition System Inspection and Maintenance Removal, Maintenance, and Installation of Ignition System Components
- Engine Starting System
- Reciprocating Engine Starting Systems
- Reciprocating Engine Starting System Maintenance Practices
- Gas Turbine Engine Starters
- Electric Starting Systems and Starter Generator Starting System
- Air Turbine Starters