ignition and start systems Flashcards
what are typically the three main components of a turbine engine ignition system?
- ignition exciters
- high tension leads
- igniters
name three sources of high volume, low pressure compressed air commonly used for starting jet transport aircraft equipped with air turbine starters
- on-board auxiliary power unit (APU)
- A ground power unit (GPU)
3.compressor bleed air from an already running engine
between field and armature windings in starter-generators, which ordinarily receive current for operation in the start mode
generally both the field and the armature receive current for operation in the start mode
name two parts of a starter-generator that commonly require periodic inspection to ensure that they do not wear beyond operational limits
the commutator and brushes
what is the function of a duty cycle in relation to a turbine engine ignition system
It is the maximum that the starter motor is allowed to be energized followed by a cool down period
a duty cycle allows the operation of the ignition system for a given ammount of time, to be followed by a minimum specficed cooling down period
the remaining service life of the brushes typically used in many starter-generators can be determined by visual inspection of what
the amount of wear groove remaining on the brushes
are turbine engine spark igniters generally susceptible to carbon fouling? explain
no, because the high-energy sparks they produce clean off any deposits that form on the firing end
what is the main concern when preparing a magneto for installation
internal timing
what does a magneto timing light indicate
it indicates the exact instant that the magneto points open.
what are the three events required to fire a spark plug in a cylinder when its piston is in the prescribed position
magneto in E-gap position
breaker points opening
and the distributor electrically aligned with that cylinder
which magneto is grounded when the magneto switch is selected to the right magneto
the left magneto
what is the purpose of using two magnetos in an engine’s ignition system
system redundancy ( safety ) and improved combustion efficiency
when an ignition switch is off in a magneto system, what is the condition of the ground circuit?
the circuit to ground is complete
what is the purpose of a magneto
a magneto produces a high voltage that forces a spark to arc across the spark plug gap
what happens when a magnetic rotor is in the E-gap position and the primary breaker points open
the flow of current in the primary circuit stops and a high rate of flux change occurs in the core, inducing a pulse of high voltage in the secondary (the spark plug fires)
