Electrical / ignition Flashcards
What components of the starter generator require periodic inspecting
commutator and brushes should be inspected for wear beyond operational limits
Between field and armature windings in a starter generators which ordinarily receive current for operation in the start mode
Generally both field and armature do
What are the possible sources of low pressure compressed air used for starting jet transport aircraft equipped with air turbine starters
Ground power unit, an on board APU, compressed bleed air form an already running engine
When should ignition ideally occur
Specific number of degrees before the piston reaches top dead center on the compression stroke
Why are dual magnetos used in engine ignition system
To improve combustion efficiency and provide safety in case one magneto fails
What function does a magneto perform
Provides high voltage spark to arc across a spark plug gap
Name the components of a high tension magneto system
Permanent multipole rotating magnet, soft iron core and pole shoes
Name three main circuits of a high tension magneto system
Magnetic, primary, and secondary
What is E-gap angel
It’s a point a few degrees past the neutral position of a rotating magnet.
What reduces arcing in the points and aids the collapsing of the magnetic field in a magneto
Capacitor
What is a magneto time in flight used for and what does it indicate
Used for internal magneto timing and magneto to engine timing. It indicates when the points are open
Why are turbine engine igniters generally not susceptible to carbon fouling
Because high energy sparks cleans off any deposits in the firing end
What does the speed of a rotation and number of poles of an alternator determine
Frequency of the alternator output
What is the most common type of alternator used in most aircraft AC systems
Three phase alternator
How is the voltage of a DC generator controlled
By varying the field current strength
Where would you find generator rating and performance data
On the data plate attached to the generator
What are the three mani components of a turbine engine ignition system
Ignition exciters, high tension leads, and igniters
What is done to ensure that each generator shares the load in a multiple generator system
Generators are parallel
How can the remaining service life of a starter generated brushes be determined
By visually inspecting the amount of wear remaining on the brushes
What is a magneto
A self contained AC generator driven by the engine for ignition to start a reciprocating engine
What is a dual magneto
It is two magnetos that are in one housing. They share the cam, and rotating magnet but have separate sets of points, coils, and distributor blocks
What is internal timing of a magneto
It’s when the breaker points are adjusted to open when the poles of the rotating magnet are at the E-gap position
Why is magneto timing so important
For an engine to run properly
