FAA regulated questions part-1

• The type of electric wire terminals used for most aircraft applications, in addition to providing good carrying capabilities, are designed primarily-- to prevent circuit failure due to terminal disconnection.
• To test generator or motor armature windings for opens,--Place armature in a growler and connect a 110V test light on adjacent segments, light should lit.
• What is the color & orientation of the position lights for navigation on civil airplanes?--Left side-red, Right side- green, Rear aft- white.
• To what depth is the mica insulation between the commutator bars of a dc generator undercut?-- Equal to the width of the mica.
• A voltage regulator controls generator output by-- Varying current flow to generator field coil.
• Which type of dc generator is not used as an airplane generator?-- Series wound.
• What is the most accurate type of frequency- measuring instrument?- Integrated circuit chip having a clock circuit.
• During ground operation, aircraft generator cooling is usually accomplished by--An integral fan.
• What does a rectifier do?- Changes AC into DC.
• What type of instrument is used to measuring very high values of resistance?- Megohmmeter.
• When a diode is checked for an open circuit or a short circuit, it should be-- Disconnected from the circuit.
• When handling a high voltage capacitor in an electrical circuit, be sure it--Is fully discharged before removing it from the circuit.
• Cause of Thermal-Runaway in a Ni-Cd battery-- Excessive current draw from the battery.
• How can it be determined if a transfomer winding has some of its turns shorted together?--The transformer will get hot in normal operation.
•  For general electrical use in aircraft, the acceptance method of attaching a terminal to a wire is by--Crimping.

FAA regulated questions..

• Some electric motors have 2 sets of field windings wound in opposite directions so that the--Motor can be operated in either direction.
•  One purpose of growler test is to determine the presence of-- A shorted armature.
• Electric wire terminals for most aircraft applications must be what type?-- Ring type.
• Principle advantage of the Series wound DC motor--- High Starting Torque.
• If a generator is equipped with a vibrator-type voltage regulator, the actual time the voltage regulator points remains open---Depends on the load carried by the generator.
• What is the cause of generator brush arcing?-- Low Spring Tension.
• When AC generators are operated in parallel, the--- Frequency and Voltage must be equal.
• The starting current of a series-wound DC motor, in passing through both the field and armature windings produces a--- High Starting Torque.
• Which motor would bee most likely to have an armature brake?-- Landing light Retraction Motor.
• The method most often used in overcoming the effect of armature reaction is through the use of--Interpoles.
• The only practical method of maintaining a constant voltage output from an aircraft generator under varying conditions of speed and load is to vary the-- Strength of the magnetic field.
• The pole pieces or shoes used in a DC generator are a part of the-- Field assembly.
• How many cycles of AC voltage are produced in a six-pole alternator of the revolving-field type for each revolution of the rotor?-- Three
• If the reverse current cut-out relay( RCCR) contact points fall to open after the generator output has dropped below battery potential, current will flow through the generator armature-- Opposite the normal direction and through the shunt field in the normal direction.
• How does the magnetic brake used to stop rotation of an electric motor armature operate?-- A friction brake is applied by a spring and released by a magnet.
• In a generator, what eliminates any possible sparking to the brush guides caused by the movement of the brushes within the holder?-- The Brush Pigtail.
• A series-wound DC electric motor will normally require--More current at low RPM than at high RPM.
• Aluminium wire must be stripped very carefully because-- Individual strands will break easily after being nicked.
• The commutator of a generator-- Changes AC produced in the armature into DC as it taken from the armature.
• An ammeter in a battery charging system is for the purpose of indicating the-- Rate of current used to charge the battery.
• Not the purpose of interpoles in a generator----- Reduce Field Strength.

Notes on Electrical system-2

• Purpose of Trickle charging of batteries- To keep it fresh and fully charged.
• Capacity of Lead-acid battery doesnt' depends upon- Rate of charge.
• Internal resistance of battery is reduced by-  a)Increase the size of the plate,

                                                                             b) Multiply the number of plates,                                                                                                                  c) Interlacing of plates.

• Efficiency of battery is increased by- 5 hour Discharge Rate.
• Batteries are rapidly charged by- Constant Voltage & Variable Current.
• Neutralizing agent of Lead-acid battery are- Baking Soda & Water.
• The electrolyte in Ni-Cd batteries performs work as a- Conductor, but not take part in chemical                                                                                               reaction.  
• Electrolyte in Ni-Cd battery is- Pottasium Hydroxide( KoH).
• CSD( Constant Speed Drive) is disconnected - Electromechanically.
•  In CSD, the UNDERDRIVE condition, pressure will be- Increases.
• Main purpose of using core in a transformer--- Decrease reluctance of common magnetic circuit.
• Transformer is not used as an Amplifier because- It doesn't provide Power Gain.
• Lamination of a transformer depends upon-- Frequency.
• An electric motor in which both the rotor and the stator field rotates with the same speed is called--                                                                                                                          Synchronous Motor.
• For parallel operation, AC polyphase altenator must have the same-- Voltage Rating.
• What will happen, if we interchange two phases of a three phase induction motor?-- The direction of rotation will be reversed.
• Type of motor used in direct cranking of engine-- DC Series Wound.
• Thickness of laminations reduced in a transformer to- Reduce Eddy Current.
• Operating current of LED-- 20 to 30 mA.
• In Double squirrel cage Induction motor the outer stage has-- High Resistance.
• Electrostatic Voltmeter measures-- AC & DC.
• An aircraft battery requires frequent addition of water due to-- Leakage & Defective cell.
• What is the value of capacitor with colour coding Red, Green,Black & Grey?-- 25pF
• The average value of unsymmetrical alternating current is considered across- 1 Complete Cycle. 
• What is not essential condition for parallel operation of 2 one phase transformer, is that they should have the --- Same Polarity.
• If the primary of step-up transformer is connected to load by mistake and secondary is supplied with voltage--- It will act as step-down transformer.
• Operation of LCD-- It doesn't emit light & depends on light falling on it.
• In a PN junction, the depletion layer is formed due to-- Mobilization of majority carrier.
• The APU serves the purpose of- Supplying electrical and pneumatic power as required.
• The main field of the generator in the brushless alternator is excited from-- Field connected to the rotating rectifier.
• Flashing of field is not required in brushless alternator because Percent voltage build up is achieved by--DC supply from GCU, is supplied continuously.
• A VTVM produces negligible loading effect on a circuit under a test because- Of its very high internal resistance.
• When servicing a DC generator, a dark film is found on commutator--It should be cleaned with no.000 sand paper.
• The dirt on the NI-Cd battery is cleaned with- De mineralized water.
• The meter used to measure the voltage of individual cells of the battery-- Normal Voltmeter.
• In CRO, what actually is done by varying intensity control-- Negative Grid base.

Notes on Aircraft Electrical System-1

These notes will help you all in your semester as well as in DGCA examinations.
             These are refined notes which I had made with lot of efforts and hours of study.
Whomsoever, get through these notes will definitely boosts up to face such examinations.......

Here, I begins......

•  Generating system of an aircraft charges the battery is designed for Varying current
• DC armature winding is closed one
• Lap winding works on Low voltage & High current
• Wave winding works on High voltage & Low current
• Coil sides are pole pitch apart ( DC armature) from Full pitch winding
• Commutator in Dc Generator converts Induced AC into DC
• For coil span equal to pole pitch, Black pitch should be equal to commutator bars/poles.
• Wave winding should have at least TWICE around the armature before it closes back.
• Critical resistance of DC generator equal to  Field resistance.
• In DC generator, generated EMF is directly proportional to Pole flux.
• Efficiency of  shunt generator is maximum when, Variable loss = Constant loss.
• Series field of short shunt DC generator is excited by Load current.
• Shunt generator in a stable parallel operations shows Dropping voltage characteristics.
• Shunt generator in unstable parallel operations shows Rising voltage characteristics.
• Equalizer bars in parallel operations Stabilize operation of 2 over- compounded DC generators.
•  2 parallel shunt generators divide the total load equally in proportion to their KW output ratings only when they have same Rated voltage. 
• Under compound shunt generator not use equalizer for stable parallel operations.
• Over-compounded shunt generator use equalizer for stable parallel operation.
• Ohm-meter used to check Continuity and Resistance.
• Reading of Ohm-meter in open-circuit condition--Infinite resistance
•  Reading of Ohm-meter in short/continuous condition--Zero.
• In aircraft, protection of batteries should be done against--Internal resistance.
• High frequency & Low current measurements should be done by Thermocouple meter.
• Speed control of DC motor done by- Thyristor
• Power/Voltage transformer is a Constant power device.
• Voltage applied to LCD should be of Low voltage, Low frequency, Out of phase AC and AC with opposite polarity.
• Series generator have Poorest voltage regulation.
• Ideal generator have Zero voltage regulation.
• Compound DC generators are mostly used because Degree of compounding can be adjusted by using a divertor across a series field.
• In DC generator, voltage buildup process is Cumulative.
• Voltage regulator in a circuit is located parallel to the output.
• When a battery is nearly discharged, the voltage reduces with load.
• If aircraft is not bonded correctly, will lead aircraft skin to be corroded. 
• Circuit which has the earth going to the aircraft structure is known as Single Pole.
• Static wick discharger, discharges in flight only.
• Screening is used to reduce radio interference.
• Circuit Breaker(CB) is resettable.
• Battery protection unit protects batteries against an internal heat.
• Motor used for engine starting is Series wound.
• Relay is an Electromagnetic Switch.
• Fuses are rated according to Amount of current they carry( in amps.)
• Purpose of a Differential Cut-Out------It ensures that the generator are nearly the same before they come alive.
• A magneto is switched off by Open circuiting the primary  circuit.
• An impulse coupling in a magneto is provided to Generate  high voltage for starting.
• Loads on aircraft busbar should be in Parallel to reduce        current.
• Extinguishant use on magnesium fire----- Sand.
• Extinguishant use on brake fire----- Dry powder.
• Passenger Oxygen drop down mask stowage doors are released-------a) Electrically for chemical oxygen generators.                          b) Pneumatically for gaseous systems.
• Type of smoke detection system fitted to an aircraft--Optical & Ionisation type.