CARAVAN FLTSFT MAN Flashcards
what is the electrical system of the caravan ?
28 Volts DC
page 2-1
what are the Volts of the Lead Acid Battery ?
24 Volts
page 2-1
what supplies primary power to the electrical system once the engine has started ?
the starter generator
page 2-1
is additional power available to the electrical system ?
yes
page 2-1
what are the TWO additional power sources to the electrical system ?
EPU
STBY ALT
page 2-1
to which buses is the DC power routed to ?
- power distribution bus
- battery bus
- general bus (x2)
- avionics bus (x2)
- standby alternator bus
page 2-1
what is the particularity of the Battery Bus ?
it is a Hot Bus which mean it energises continuously for cabin/courtesy lights and other functions requiring power when the two general buses are off
page 2-3
where is the battery located ?
on the right forward side of the firewall on a swing-out tray
page 2-3
does the battery have also the role of absorbing voltage spikes ?
yes
page2-3
why is the battery case ventilated ?
to prevent a concentrated accumulation of hydrogen within the airframe
page 2-3
What is the other role of the battery overboard vent ?
to drain any acid condensation produce during system charging
page 2-3
where is the Generator Control Unit located ?
on the left forward fuselage sidewall
page 2-4
what does the GCU do ?
provides the electrical control functions of the starter-generator
page 2-4
at what Ng percentage does the GCU automatically cuts off the starter ?
46%
page 2-4
once the Ng have reached above 46% what happens to the starter-generator ?
it functions as a generator an no longer as a starter once the Starter Switch is position to OFF
page 2-4
where is the starter-generator position ?
12 o’clock position on the accessory gear box (AGB)
page 2-4
what runs the starter-generator ?
is driven by the engine through a splined shaft
page 2-4
what are the Volt and Amps of the Generator ?
28 Volts 200Amps (300Amps optional)
page 2-4
describe the cooling system for the starter-generator ?
an integral fan and blast tube above the oil cooler in the air inlet on the right forward cooling cools the starter-generator
page 2-4
does the GCU have an overspeed sensor ?
yes
page 2-4
does the GCU have an automatic starter shut off ?
yes
page 2-4
what prevents an external power to battery connection during engine start ?
the external power control circuit
page 2-4
what else does the ground service circuit protect the aircraft electrical system from ?
- polarity reversal: if the plug is plugged the wrong way
- overvoltage protection
page 2-5
what is the role of the ground power monitor ?
to close the external power contactor when the applied voltage is within the proper limits
page 2-5
describe the components of the Standby Electrical Power System ?
- 75 Amps Alternator (belt driven from the accessory pad)
- ACU
- Standby Alternator Contactor
- Two Switches: Avionics STBY PWR, Avionics BUS TIE
page 2-5
When the EPU switch is OFF….?
external power goes to the ground power unit only
page 2-5
When the EPU switch is on STARTER…?
- external power goes to the starter circuit only
(battery power is applied to the main bus) - no generator power is available
page 2-5
When the EPU switch is on BUS…?
- the external power goes to the power distribution bus
- no power to the starter
page 2-5
how do you connect the battery to the power distribution bus and external power ?
Battery Switch to ON
page 2-5
when the Battery switch is ON….?
battery power is supplied to the 2 general buses
page 2-6
when the Battery switch is OFF…?
power is deactivated to all the buses except the battery bus (HOT BUS)
page 2-6
describe the three position of the spring loaded Generator Switch ?
RESET, ON, TRIP
page 2-6
describe the IGNITION Switch ?
ON: the igniters will ignite constantly
NORM: the igniters will ignite when the STARTER switch is on START
page 2-6
describe the STARTER Switch ?
- OFF: deenergizes the ignition system
- START: energises the ignition system when on NORMAL, once the engine is self sustaining it must be position to OFF
- MOTOR: motors the engine without the ignition system energising
page 2-6
is the STARTER switch spring loaded ?
only when selected to the motoring position. once release it will spring load to OFF
page 2-6
what does the inter-lock between the MOTOR position of the STARTER switch and the IGNITION switch does ?
it prevents the starter from starter from motoring unless the IGNITION switch is positioned to NORM
page 2-6
what does the Avionics BUS TIE switch do ?
connect the No1 and No2 avionics buses if either bus feeder circuit fails
page 2-6