Ignition and Starting Systems Part 4 Flashcards
What will be the results of increasing the gap of the breaker points in a magneto?
Advance the spark and decrease its intensity.
Pneumatic starters are usually designed with what type of airflow impingement systems?
Radial inward flow turbine and axial-flow turbine.
In order to turn off a magneto, the primary circuit must be
grounded.
When a “Shower of Sparks” ignition system is activated at an engine start, a spark plug fires
only while both the retard and advanced breaker points are open.
Which of the following are advantages of dual ignition in aircraft engines?
1. Gives a more complete and quick combustion of the fuel.
2. Provides a backup magneto system.
3. Increases the output power of the engine.
4. Permits the use of lower grade fuels.
5. Increases the intensity of the spark at the spark plugs.
1, 2, 3.
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,
only No. 2 is true.
Magneto breaker point opening relative to the position of the rotating magnet and distributor rotor (internal timing) can be set most accurately
during assembly of the magneto before installation on the engine.
Why are turbine engine igniters less susceptible to fouling than reciprocating engine spark plugs?
The high intensity spark cleans the igniter.
When will the voltage in the secondary winding of a magneto, installed on a normally operating engine, be at its highest value?
Just prior to spark plug firing.
What component of a dual magneto is shared by both ignition systems?
Rotating magnet.
One of the best indicators of reciprocating engine combustion chamber problems is
spark plug condition.
What is the purpose of using an impulse coupling with a magneto?
To produce a momentary high rotational speed of the magneto.
What type of igniter plug is used in the low tension ignition system of an aircraft turbofan engine?
Self-ionizing or shunted-gap type plug.
Magneto pole shoes are generally made of
laminations of high-grade soft iron.
(Refer to Figure 5.) The type of system depicted is capable of operating with
either battery or external power.
When performing a magneto ground check on an engine, correct operation is indicated by
a slight drop in RPM.
Alignment of the marks provided for internal timing of a magneto indicates that the
magneto is in the E-gap position.
(Refer to Figure 5.) Which malfunctions will allow the igniters to operate normally during start but be inoperative when tested?
1. Conductor No. 14 broken.
2. Conductor No. 10 broken.
3. Conductor No. 15 broken.
4. Conductor No. 12 broken.
1 or 3.
One way that the automatic ignition relight systems are activated on gas turbine engines is by a
drop in compressor discharge pressure.
In a high tension ignition system, a primary capacitor of too low a capacity will cause
the breaker contacts to burn.
Which of the following, obtained during magneto check at 1,700 RPM, indicates a short (grounded) circuit between the right magneto primary and the ignition switch?
BOTH-1,700 RPM; R-0 RPM; L-1,000 RPM; OFF-0 RPM.
How is the strength of a magneto magnet checked?
Hold the points open and check the output of the primary coil with an ac ammeter while operating the magneto at a specific speed.
What is the difference between a low tension and high tension engine ignition system?
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.
The electrical circuit from the spark plug back to the magneto is completed by grounding through the
engine structure.
What is the relationship between distributor and crankshaft speed of aircraft reciprocating engines?
The distributor turns at one half crankshaft speed.
If the ground wire of a magneto is disconnected at the ignition switch, the result will be the
engine will not stop running when the ignition switch is turned off.
If it is found that a shielded ignition system does not adequate reduce ignition noise, it may be necessary to install
a filter between the magneto and magneto switch.
A defective primary capacitor in a magneto is indicated by
burned and pitted breaker points.
(Refer to figure 5.) Placing the engine master switch and battery switch to the on position and advancing the power lever, allows current to flow from the bus to the
fuel valve, start switch, power lever switch, power lever relay coil, fuel pump switch, and one side of the ignition relay contactor.
