Ignition and Starting Systems Part 1 Flashcards
When a magneto is operating, what is the probable cause for a shift in internal timing?
The cam follower wear and/or the breaker points wear.
(Refer to figure 5.) When an external power source is connected to the aircraft,
the battery cannot be connected to the bus.
When internally timing a magneto, the breaker points begin to open when
the magnet poles are just a few degrees beyond the neutral position.
At what RPM is a reciprocating engine ignition switch check made?
The slowest possible RPM.
What is the electrical location of the condenser in a high-tension magneto?
In parallel with the breaker points.
The amount of voltage generated in any magneto secondary coil is determined by the number of windings and by the
rate of collapse of the magnetic field around the primary coil.
Which of the following are distinct circuits of a high tension magneto?
1. Magnetic
2. Primary
3. E gap
4. P lead
5. Secondary.
1, 2, 5.
What will be the effect if the spark plugs are gapped too wide?
Hard starting.
Which statement is correct regarding the ignition system of a turbine engine?
The system is normally de-energized as soon as the engine starts.
The term “reach”, as applied to spark plug design and/or type, indicates the
linear distance from the shell gasket seat to the end of the threads on the shell skirt.
The primary advantage of pneumatic (air turbine) starters over comparable electric starters for turbine engines is
high power-to-weight ratio.
When installing a magneto on an engine, the
piston in the No. 1 cylinder must be a prescribed number of degrees before top dead center on the compression stroke.
In a low tension ignition system, each spark plug requires an individual
secondary coil.
What would be the result if a magneto breaker point mainspring did not have sufficient tension?
The points will float or bounce.
Which of the following statements regarding magneto switch circuits is NOT true?
In the BOTH position, the right and left magneto circuits are grounded.
Why do turbine engine ignition systems require high energy?
To ignite the fuel under conditions of high altitude and low temperatures.
Which of the following are included in a typical turbine engine ignition system?
1. Two igniter plugs
2. Two transformers
3. One exciter unit
4. Two intermediate ignition leads
5. Two low tension igniter leads
6. Two high tension plugs
1, 3, 6.
How does the ignition system of a gas turbine engine differ from that of a reciprocating engine?
Magneto to engine timing is not critical.
Air turbine starters are generally designed so that reduction gear distress or damage may be detected by
inspection of a magnetic chip detector.
What type of electric motor is generally used with a direct-cranking engine starter?
Direct current, series-wound motor.
The E gap angle is usually defined as the number of degrees between the neutral position of the rotating magnet and the position
where the contact points open.
Spark plug heat range is determined by
its ability to transfer heat to the cylinder head.
What instrument could be used to test an ignition harness for suspected leakage.
A high tension lead tester.
When a magneto is disassembled, keepers are usually across the poles of the rotating magnet to reduce the loss of magnetism. These keepers are usually made of
soft iron.
Failure of an engine to cease firing after turning the magneto switch off is an indication of
an open P-lead to ground.
When internally timing a magneto, the breaker points begin to open when the rotating magnet is
a few degrees past the neutral position.
Upon inspection of the spark plugs in an aircraft engine, the plugs were found caked with a heavy black soot. This indicates
a rich mixture.
Why are high-tension ignition cables frequently routed from the distributor to the spark plugs in flexible metallic conduits?
To reduce the effect of the high-frequency electromagnetic waves emanated during operation.
Capacitance after-firing of a spark plug is caused by
the stored energy in the ignition shielded lead unloading after normal timed ignition.
