Pp Electrical, Starting, & Ignition Systems

Front 1

How can the remaining service life of starter generator brushes be determined

Back 1

By visually inspecting the amount of wear groove remaining on the brushes

Front 2

What components of the starter generator require periodic inspection

Back 2

Commutator & Brushes should be inspected for wear beyond operational limits

Front 3

Between field and Armature windings in starter generators, which ordinarily receive current for operation in the start mode

Back 3

Generally both field and Armature receive current for operation in the start mode

Front 4

What are possible sources of low-pressure compressed air used for starting jet transport aircraft equipped with air turbine starters

Back 4

1. A ground power unit (GPU)
2. An onboard auxiliary power unit (APU)
3. Compressed bleed air from an already running engine

Front 5

When should ignition ideally occur

Back 5

A specific number of degrees as (determined by the manufacturer) before the piston reaches top dead center on the compression stroke

Front 6

Why are Dual magnetos used in the engine ignition system

Back 6

1. To improve combustion efficiency
2. to provide redundancy for safety

Front 7

Why is magneto timing so important

Back 7

For an engine to run properly, the spark plug in a cylinder has to fire at a specific time.

To produce the required energy for the spark at the required time, the magneto must be in the E-gap position, the breaker points must start to open, and the distributor must be electrically aligned with the particular cylinder.

If any of these requirements are not correctly adjusted, the engine will run rough or may not run at all.

When preparing a magneto for installation, first the internal timing must be correctly adjusted then the magneto-to-engine timing is adjusted

Front 8

What function does a magneto perform

Back 8

It produces a high-voltage that forces a spark to arc across a spark plug gap

Front 9

Name the components of a high tension magneto system

Back 9

1. Permanent multipole rotating magnet
2. Soft iron core
3. Pole shoes

Front 10

Name the three main circuits of a high tension magneto system

Back 10

1. Magnetic
2. Primary
3. Secondary

Front 11

What is an E gap angle

Back 11

It is a point a few degrees beyond the neutral position of a rotating magnet where maximum magnetic field stress exists

Front 12

What reduces arcing in the points and also aids the collapsing of the magnetic field in a magneto

Back 12

A capacitor

Front 13

How does a magneto produce the high-voltage required to fire a spark plug

Back 13

In the rotation cycle, when the magnetic rotor is in the Egap position the primary points open, which interrupts the current flow in the primary circuit causing a high rate of flux change in the core and inducing a pulse of high voltage in the secondary coil

Front 14

What is the P-lead and how does it function

Back 14

The P lead connects the ignition switch to the primary circuit of the magneto. When the ignition switch is turned off, the P-leads on both magnetos are grounded. When the ignition switch is turned to the "left" position, the right magneto is grounded, so that only the left magneto operates, and vice versa

Front 15

What is a magneto timing light used for and what does it indicate

Back 15

It is used for both internal magneto timing and magneto-to-engine timing, and indicates the exact instant the magneto points open

Front 16

Why are turbine engine igniters generally not susceptible to carbon fowling

Back 16

Because the high energy sparks they produce clean off any deposits on the firing end

Front 17

What is the function of a duty cycle in relation to a turbine engine ignition system

Back 17

A duty cycle allows the operation of the ignition system for a given amount of time, and is then followed by a minimum specified cooling down period

Front 18

What are the three main components of a turbine engine ignition system

Back 18

1. Ignition exciters
2. High tension leads
3. Igniters

Front 19

When the engine is operating what does an ammeter/loadmeter indicate when connected to:
1. battery positive lead
2. generator output lead

Back 19

1. When connected to the battery positive lead the ammeter indicates whether the battery is charging or discharging

2. When connected to the generator output lead it indicates the current produced by the generator or electrical system load

Front 20

What is done to ensure that each generator shares the load in a multiple generator system

Back 20

The generators are paralleled

Front 21

Where would you find generator rating and performance data

Back 21

On the data plate attached to the generator

Front 22

How is the voltage of a DC generator controlled

Back 22

By varying the field current strength

Front 23

What is the most common type of alternator used in most aircraft AC systems

Back 23

The three phase alternator

Front 24

How does a voltage regulator control the Voltage of an alternator

Back 24

By regulating the voltage output of the DC exciter

Front 25

What does the speed of rotation and number of poles of an alternator determine

Back 25

The frequency of the alternator output

Front 26

What are some of the methods used to maintain 400 Hz alternator output frequency on large turbojet or Turbofan engines

Back 26

1. Constant speed drives
2. Integrated drive generators
3. Variable speed constant frequency (VSCF) power systems

Front 27

Name the major parts of a DC motor

Back 27

1. Armature
2. Field
3. Brushes
4. Frame assembly

Front 28

Name the components of a direct cranking electric starter system

Back 28

1. An electric motor
2. Reduction gears
3. An automatic engaging & disengaging mechanism

Front 29

Name 3 types of DC motors

Back 29

1. Series
2. Shunt
3. Compound

Front 30

What type of DC motor is commonly used for a reciprocating engine starter and why

Back 30

A series wound motor is commonly used because it has a high starting torque under heavy load conditions

Front 31

What are the operating modes of a turbine engine starter Generator

Back 31

It operates first as a starter then as a generator once the engine is running

Front 32

What is a possible indication when a starter drags

Back 32

A dirty or worn starter commutator

Front 33

Where would wire with high temperature insulation material be used

Back 33

When they run close to high temperature areas such as exhaust stacks or heating ducts

Front 34

What is the size standard for electrical wiring used in US manufactured aircraft

Back 34

The American wire gauge AWG

Front 35

How are wire sizes represented

Back 35

By a number gauged size. The smaller wires are represented by larger numbers. The smallest size wire normally used in aircraft is 22 gauge

Front 36

What is the maximum slack allowed between the supports of a single wire or bundle installation

Back 36

Not over 1/2 inch

Front 37

Why are wires bonded on power plant installations

Back 37

To provide a current return path for electrical assessories and to prevent static discharge