ELECTRICAL SYSTEM Flashcards
1
Q
What is the PA44 electrical system?
A
- negative-ground (negative terminal connected to ground)
- dual-fed (electrical power from 2 alternators)
- split-bus
- two-belt driven
- 28 Volt 65 Amp alternators mounted on each engine
2
Q
What does the alternators have to protect it from a malfunction?
A
- voltage regulator
- overvoltage relay
3
Q
What is a voltage regulator?
A
- electronic device that maintains a constant output of voltage
4
Q
What is an over voltage relay?
A
- a device that will take the alternator offline if it exceeds 32 volts
5
Q
What are the alternators limitations?
A
- max load ground is 60 amps
- max load flight is 65 amps
6
Q
What is the role of the BATT in the a/c?
A
- aids in starting the a/c
- use of electrical equipment when a/c is not running
- electrical storage to back up alternator output
- located in nose section, kept charged by the alternators
7
Q
What is the role of circuit breakers?
A
- protect the electrical system
- contains a metal piece where electric will move through
- metal will expand due to heat
- metal will get hot and expand a great deal and “pop” the circuit
- re-setting the circuit, allow for a cool down period (few minutes)
- fire could start with repeated re-setting
8
Q
What is the Emergency BATT?
A
- provides electrical power to a/c during complete electrical failure or when electric is not sufficient
- emergency bus powers standby instruments, all PFD functions (except COM 2/NAV 2)
- 30 minutes of electrical power
- isolated from emergency bus by a relay
- diode isolated, allows for charging during normal ops
9
Q
What is a solenoid contactor?
A
- high powered switch that uses coils to activate set of contacts
10
Q
What is the BATT bus?
A
- located in battery compartment
- source of power for the clock, engine Hobbs, flight Hobbs, and heater
- since connected directly to battery, power is available even when MSTR switch is OFF
11
Q
What is the ESS Bus?
A
- is a power distribution bus in an aircraft that supplies power to critical equipment
- 70 amp circuit breaker over current protection
12
Q
What is a tie bus?
A
- simply connects two bus bars together
- like the engine generators or auxiliary power unit (APU), to be connected together (tied) on a single electrical bus
13
Q
What is a non-essential bus?
A
- power circuit that supplies power to systems or components that are not critical for the safe operation of the aircraft
- can be deactivated quickly to help reduce electrical load in case of alternator failures
14
Q
Can we start the a/c externally on the ground?
A
- external can be used to power the a/c
- good to start one engine w/ external power & other with a/c power
15
Q
What happens when you turn on the alternators?
A
- positive output fed through shunts (device creates low resistance for electrical currents) to tie bus
- current from tie bus fed to avionics bus through a solenoid contacter
- overcurrent protection 80 amp tie bus
16
Q
What is a volt? What is an amp?
A
- force of an electrical current (pressure)
- volume of electrons flowing
17
Q
Limitations of the Main & Emergency BATT?
A
- Main (minimum 25 volts & maximum 32 volts)
- Emergency (minimum 20 volts, minimum for IFR 23.3 volts & maximum 32 volts)
18
Q
What are the specifications of the BATT?
A
- 13.6 amp hr. 24 volt
- nose compartment
- charged by 14 volt alternators
- BATT & alternator incorporate a contactor
- BATT master switch activates BATT contractor which connects the BATT to the system (keeps large amounts of electricity from pilot & reduces weights/wires)
19
Q
What are the specifications of the G1000 system?
A
- 10” lcd screens PFD & MFD
20
Q
What features are equipped on the PFD?
A
- AHRS
- ADC
- VOR/Localizer/GS
- CAS (crew alerting system) warning messages
21
Q
What features are equipped on the MFD?
A
- engine parameters
- a/c system parameters
- various maps
- traffic map, weather, TAWS (terrain avoidance & warning system)
22
Q
What is AHRS? (MAG & AHRS-W)
A
- attitude heading reference system
- inputs: ADC, GPS, Magnetometer
- outputs: attitude indicator, heading indicator, rate of turn, slip/skid, wind vector
23
Q
What is ADC?
A
- air data computer
- inputs: OAT probe, pitot/static, alternate static
- outputs: OAT, TAS, IAS, VSI, ALT, E6B calc., wind vectors, mode c transponder
24
Q
What are solid state gyros?
A
- there are in the G1000 system
- mounted vertically & horizontally
- tiny free floating accelerometer works off of Coriolis acceleration
- some use laser lights that track time it takes to move around a fixed object
- they are durable & accurate
25
What is a magnetometer?
- 3 soft iron rods, wound in copper coils that can accept the flux lines of Earth
- measures amount of flux from the Earths magnetic field and calculates current heading
26
What is a VOR?
- Very High Omnidirectional Range
- VOR receiver receives 2 signal (reference & variable signal)
- broadcasts signal in all directions
- detects the phase difference to determine the radial
27
What is a DME?
- Distance Measuring Equip.
- interrogation frequency pulse received by ground stations
- sends reply pulse where a/c measures the time between the process to determine distance
28
What is GPS?
- Global Positioning System
- Spaced based nav.
- 30+ satellites
- 24 for timing & range that orbit Earth
- satellites use an atomic clock which is down to the billionth of a second
- 3 sats for 2D (position), 4 sats for 3D (position & altitude), 5 sats for RAIM, 6 sats for FDE
- position, velocity, & time
29
What is WAAS?
- Wide Area Augmentation System
- increases accuracy of GPS system
- 50 ft to 10 ft of accuracy
- reference stations, master stations, geo satellites, uplink station
30
What is RAIM?
- Receiver Autonomous Integrity Monitoring
- monitors strength & integrity of GPS signals
- FDE will exclude or removed faulty signal
31
What is the ILS system?
- Instrument Landing System
- approach
- guidance, range, & visual
er side, 10 NM 35 degrees either side, width 700 ft.
32
ILS Guidance
- localizer, antenna DER, two signals emitted, coverage 18 NM 10 degrees either side, 10 NM 35 degrees either side, width 700 ft.
- glide slope: localizer on its side, 3 degree glide slope, beam 1.4 degrees thick 0.7 is full scale deflection 750-1250 feet past approach end
33
ILS Range
- DME
- marker beacons: used to identify fixes, antennas on ground, flashing lights Outer (blue), Middle (amber), Inner (white)
- we use GPS
34
Visual Info for ILS
- approach lights
- touchdown/centerline lights
- runway lighting
- approach lighting system
- runway threshold/threshold lights
- REIL
- runway pavement
35
What is an HSI?
- A Horizontal Situation Indicator (HSI) is a flight instrument that shows an aircraft's position and orientation relative to its course
- It's a vital navigation tool that combines a heading indicator with a course deviation indicator (CDI)
36
What are the Autopilot Limitations?
- AP disengaged during T/O & LDG
- 400 ft. T/O or subsequent climb
- 1000 ft. cruise & descent
- 200 ft. on approach
- speed on approach 90 KTS
- other than approach 80 KTS
- max speed 190
- max fuel imbalance 10 gal.
- AP prohibited during OEI
- pitch +/- 50 degrees
- roll +/- 75 degrees
37
What is a bus?
- a central connection point, usually a metallic conductor called a "bus bar," where multiple electrical circuits converge to distribute power from incoming feeders to outgoing feeders
38
CAUTION for emergency battery
- will only provide 30 minutes of power if the voltage at the time of electrical failure is greater than 23.3 volts
