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
