Aircraft Electrical

Aircraft fuse capacity is rated in A. volts B. ohms C. amperes

Amps

What is required when operating two aircraft AC generators in parallel? A) Amperes and Frequency must both be equal B) Frequency and Voltage must both be equal C) Amperes and Voltage must both be equal

B) Frequency and Voltage must both be equal

What is the color and orientation of the position lights for navigation on civil airplanes? A) Left side - green, right side - red, rear aft - white. B) Left side - red, right side - green, rear aft - white. C) Left side - white, right side - green, rear aft - red.

B) Left side - red, right side - green, rear aft - white.

Where electric cables must pass through holes in bulkheads, formers, ribs, firewalls, etc., the wires should be protected from chafing by... A) wrapping with electrical tape B) using a suitable grommet C) wrapping witch plastic

B) using a suitable grommet

Which motor would be most likely to have an armature brake?? A. Starter Motor B. Landing Light Retraction Motor C. Inverter Drive Motor

B. Landing Light Retraction Motor A landing-light retraction motor is the most likely of the motors listed here to have an armature brake. The brake causes the armature to stop turning as soon as the switch is released.

Which are True???? (1) There are three basic types of dc motors; series, shunt, and compound. (2) In the series motor, the field windings, consisting of relatively few turns of heavy wire, are connected in series with the armature winding.

Both are true

Why are the iron cores of most induction coils laminated? A) to reduce the core reluctance B) to increase the core permeability C) to reduce the effects of eddy currents

C) to reduce the effects of eddy currents

Which of the following is not one of the purposes of interpoles in a generator? A. Reduce the field strength B. Overcome the armature reaction C. Reduce arcing at the brushes

Interpoles are not used to reduce the field strength

What is the principal advantage of the series-wound dc motor? A High starting torque. B Suitable for constant speed use. C Low starting torque.

A High Starting Torque

Bonding connections should be tested for A) resistance value B) amperage value C) reactance

A bonding connection must be installed in such a manner that the resistance of each connection does not exceed 0.003 ohm.

A circuit breaker is installed in an aircraft electrical system primarily to protect the... A)circuit and should be located as close to the source as possible. B)circuit and should be located as close to the unit as possible. C)electrical unit in the circuit and should be located as close to the source as possible.

A circuit breaker is installed in an aircraft electrical system primarily to protect the circuit. It is installed as close to the source as is possible. Circuit breakers are usually mounted directly on the main bus.

If a generator is equipped with a vibrator-type voltage regulator, the actual time the voltage regulator points remain open... A depends on the load carried by the generator B is controlled by the reverse-current cutout relay point clearance C is increased when the external load is greater than the generator output

A depends on the load carried by the generator

What is the minimum bend radius for an electrical wire bundle? A) 10x outside diameter of bundle B) 5x outside diameter of bundle C) 15x outside diameter of bundle

A) 10x outside diameter of bundle

Which of the following must be accomplished when installing an anticollision light? A) Install a switch independent of the position light switch. B) Use shielded electrical cable to assure fail-safe operation. C) Connect the anticollision light to the aircraft position light switch

A) Install a switch independent of the position light switch.

What is the most accurate type of frequency-measuring instrument? A) Integrated circuit chip having a clock circuit B) Electrodynamometers using electromagnetic fields C) Electromagnets using one permanent magnet

A) Integrated circuit chip having a clock circuit The most accurate frequency-measuring instruments in use today are digital instruments that contain integrated-circuit chips and a clock circuit.

Circuits that must be operated only in an emergency or whose inadvertent activation could endanger a system frequently employ A) guarded switches. B) push-pull-type circuit breakers only (no switches). C)spring-loaded to off toggle or rocker switches.

A. When it is important that an electrical switch not be inadvertently operated, it is normally installed with a guard over its operating handle. The guard requires a conscious effort to get to the switch to actuate it.

The method most often used in overcoming the effect of the armature reaction is through the use of... A. Interpoles B. Shaded Poles C. Drum-wound armatures in combination w/a negatively connected series field

A. Interpoles If armature reaction is not corrected, it will cause the brushes to arc under certain load conditions.

What is used to measure very high values of resistance?? A. Megohmmeter B. Shunt-type ohmmeter C. Multimeter

A. Megohmmeter

The starting current of a series-wound DC motor, in passing through both the field and armature windings, produce a...

high starting torque

When approved, splices may be used to repair manufactured harnesses or installed wiring. The maximum number of splices permitted between any two connectors is A. one B. two C. three

uno

Which of the following are the major parts of a dc motor? 1. Armature assembly. 2. Field assembly. 3. Brush assembly. 4. Commutator. 5. Pole piece. 6. Rheostat. 7. End frame.

1 2 3 7

When selecting hardware for attaching bonding connections to an aircraft structure, which of the following should be considered? 1. Mechanical strength. 2. Allowable power loss. 3. Ease of installation. 4. Permissible voltage drop. 5. Amount of current to be carried. 6. Type of load (continuous or intermittent).

1 3 5

In installations where the ammeter is in the generator or alternator lead, and the regulator system does not limit the maximum current that the generator or alternator can deliver, the ammeter can be redlined at what percent of the generator or alternator rating? A) 50 B) 75 C) 100

100%

Which of the following factors must be taken into consideration when determining the wire size to use for an aircraft installation? 1. Mechanical strength. 2. Allowable power loss. 3. Ease of installation. 4. Resistance of current return path through the aircraft structure. 5. Permissible voltage drop. 6. Current carrying capability of the conductor. 7. Type of load (continuous or intermittent).

2 5 6 7

If a wire is installed so that it comes in contact with some moving parts, what protection should be given the wire? A) wrap with soft wire solder into a shield B) wrap with friction tape C) pass through conduit

Anytime an electrical cable, a wire bundle, or an individual wire comes into contact with some moving part of the aircraft, the wire must be protected by passing it through conduit.

Which of the following is most likely to cause thermal runaway in a nickel-cadmium battery? A) A high internal resistance condition. B) Excessive current draw from the battery. C) Constant current charging of the battery to more than 100 percent of its capacity.

B) Excessive current draw from the battery. Thermal runaway of a nickel-cadmium battery occurs when some of the cells become excessively hot. The heat lowers both the voltage and the resistance so the cells can accept a high rate of charging current. This high current produces more heat and the battery can destroy itself

The commutator of a generator A) changes direct current produced in the armature into alternating current as it is taken from the armature. B) changes alternating current produced in the armature into direct current as it is taken from the armature. C) reverses the current in the field coils at the proper time in order to produce direct current.

B) changes alternating current produced in the armature into direct current as it is taken from the armature.

If several long lengths of electrical cable are to be installed in rigid conduit, the possibility of damage to the cable as it is pulled through the conduit will be reduced by... A) dusting the cable with powdered graphite. B) dusting the cable with powdered soapstone. C) applying a light coat of dielectric grease.

B) dusting the cable with powdered soapstone.

One advantage of using ac electrical power in aircraft is.... A) that ac electrical motors can be reversed while dc motors cannot. B) greater ease in stepping the voltage up or down. C) that the effective voltage is 1.41 times the maximum instantaneous voltage; therefore, less power input is required.

B) greater ease in stepping the voltage up or down.

If it is necessary to use an electrical connector where it may be exposed to moisture, the mechanic should... A) Coat the connector with grease B) use a special moisture proof type C) Spray the connector with varnish or zinc-chromate

B) use a special moisture proof type

The circuit breaker in the instrument lighting system protects the... A) lights from too much current B) wiring from too much current C) wiring from too much voltage

B) wiring from too much current

What does a rectifier do??? A. Change DC into AC B. Change AC into DC C. Reduce Voltage

B. Changes AC into DC

During ground operation, aircraft generator cooling is usually accomplished by... A. auxiliary air cooled through an air/fuel heat exchanger B. an integral fan C. an external motor-driven fan

B. an integral fan (a fan that is mounted on the armature shaft).

During inspection of the terminal strips of an aircraft electrical system, it should be determined that... A. only locknuts have been used for terminal attachment to the studs B. the terminal studs are anchored against rotation C. only plain nuts and lockwashers have been used for terminal attachment to the studs

B. the terminal studs are anchored against rotation

The three kinds of circuit-protection devices used most commonly in aircraft circuits are... A.circuit breakers, resistors, and current limiters. B.circuit breakers, fuses, and current limiters. C.circuit breakers, capacitors, and current limiter plug-ins mechanical reset types.

B.circuit breakers, fuses, and current limiters.

When handling a high voltage capacitor in an electrical circuit, be sure it.. A. has a full charge before removing it from the circuit B. has at least a residual charge before removing it from the circuit C. is fully discharged before removing it from the circuit

Before removing any high-voltage capacitor, short across its terminals with an insulated-handle screwdriver to fully discharge it.

AN/MS electrical connectors are specifically designed to meet... A. TSO specs B. Military Specs C. ICAO standards

Air Force-Navy (AN) or Military Specifications (MS) electrical connectors are specifically designed to meet military specifications. Components that meet these specifications are almost all approved for use in FAA-certificated aircraft.

What is the advantage of a circuit breaker when compared to a fuse? A.Never needs replacing. B.Always eliminates the need of a switch. C.Resettable and reusable.

C A circuit breaker is resettable and reusable, whereas a fuse, once it is blown, must be replaced with a new one.

What protection to wires and cables does conduit provide when used in aircraft installations? A) Electromagnetic B) Mechanical C) Structural

Conduit is used to give mechanical protection to electrical wiring in an aircraft installation.

What is normally used to bond noncontinuous stainless steel aircraft components? A. Stainless steel jumpers B. Copper Jumpers C. Aluminum Jumpers

Copper

For general electrical use in aircraft, the acceptable method of attaching a terminal to a wire is by... A. Crimping B. Soldering C. Crimping and Soldering

Crimping

The major advantages of alternating current (AC) over direct current (DC) is the fact that its current and voltage can easily be increased or decreased... A) by means of an inverter B) by means of a rectifier C) by means of a transformer

C Alternating current may have its voltage changed to any other value of AC by the use of a transformer. A transformer does not change the power of the AC, but when the voltage is increased, the current will correspondingly decrease.

In the American Wire Gauge (AWG) system of numbers used to designate electrical wire sizes, the number assigned to a size is related to its.... A) combined resistance and current carrying capacity B) current carrying capacity C) cross sectional area

C The AWG number relates to the diameter of the wire, and therefore to its cross-sectional area.

Electric wire terminals for most aircraft applications must be what type? A Slotted B Hook C Ring

C Ring Type

One purpose of a growler test is to determine the presence of... A an out-of-round commutator. B a broken field lead. C a shorted armature.

C a shorted armature.

Some electric motors have two sets of field windings wound in opposite directions so that the.... A speed of the motor can be more closely controlled. B power output of the motor can be more closely controlled. C motor can be operated in either direction.

C motor can be operated in either direction.

How does the magnetic brake used to stop rotation of an electric motor armature operate? A) Centrifugal force releases a rotating brake cog from a stationary notch when the armature reaches a certain speed and magnetic force re-engages the cog when the electrical power is turned off. B) A friction brake is applied by a magnet and released by a spring C) A friction brake is applied by a spring and released by a magnet

C) A friction brake is applied by a spring and released by a magnet

If the (+) terminal of a voltmeter is connected to the (-) terminal of the source voltage and the (-) terminal of the meter is connected to the (+) terminal of the source voltage, the voltmeter will read.... A)correctly B)low voltage C) backwards

C) Backwards

The inductor-type inverter output voltage is controlled by the.... A)number of poles and the speed of the motor. B)voltage regulator. C) DC stator field current

C) DC stator field current

Which of the following should be accomplished in the installation of aircraft wiring? A) Support the bundle to structure and/ or solid fluid lines to prevent chafing damage. B) Provide adequate slack in the wire bundle to compensate for large changes in temperature. C) Locate the bundle above flammable fluid lines and securely clamp to structure.

C) Locate the bundle above flammable fluid lines and securely clamp to structure.

How can it be determined if a transformer winding has some of its turns shorted together? A) Measure the input voltage with an ohmmeter. B) The output voltage will be high. C) The transformer will get hot in normal operation.

C) The transformer will get hot in normal operation. If some of the windings in a transformer are shorted together, an excessive amount of current will flow in the windings and the transformer will get hot in normal operation.

What is the advantage of a current limiter? A) it breaks circuit quickly B) it can be reset easily C) it will take overload for a short period

C) it will take overload for a short period

If the reverse current cutout relay contact points fail to open after the generator output has dropped below battery potential, current will flow through the generator armature.... A) in the normal direction and through the shunt field opposite the normal direction. B) and the shunt field opposite the normal direction C) opposite the normal direction and through the shunt field in the normal direction.

C) opposite the normal direction and through the shunt field in the normal direction.

If one switch is used to control all navigation lights, the lights are most likely connected A) in series with each other and parallel to the switch. B) in series with each other and in series with the switch. C) parallel to each other and in series with the switch.

C) parallel to each other and in series with the switch.

The navigation lights of some aircraft consist of a single circuit controlled by a single switch which has an ON position and an OFF position, with no additional positions possible. This switch is referred to as a.... A) double-pole, single-throw (DPST), two-position switch. B) single-pole, double-throw (SPDT), two-position switch. C) single-pole, single-throw (SPST), two-position switch.

C) single-pole, single-throw (SPST), two-position switch.

A voltage regulator controls generator output by A) introducing a resistance in generator-to-battery lead in the event of overload. B) shorting out field coil in the event of overload. C) varying current flow to generator field coil.

C) varying current flow to generator field coil.

How does the routing of coaxial cables differ from the routing of electrical wiring? A)Coaxial cables are routed parallel with stringers or ribs. B)Coaxial cables are routed at right angles to stringers or ribs. C)Coaxial cables are routed as directly as possible.

C)Coaxial cables are routed as directly as possible.

What is the purpose of the selection of derated switches for known continuous load current applications? A)To calculate the voltage drop across the circuit. B)To prevent short circuits in the motor field windings. C)To obtain reasonable switch efficiency and service life.

C)To obtain reasonable switch efficiency and service life.

The nominal rating of electrical switches refers to continuous... A)current rating with the contacts open. B)voltage rating with the contacts closed. C)current rating with the contacts closed.

C)current rating with the contacts closed.

Certain transport aircraft use ac electrical power for all normal operation and battery furnished dc electrical power for standby emergency use. In aircraft of this type that operate no dc generators, the batteries are kept charged by..... A)inverters which use the aircraft's ac generators as a source of power. B)alternators which use the aircraft's generators as a source of power. C)rectifiers which use the aircraft's ac generators as a source of power.

C)rectifiers which use the aircraft's ac generators as a source of power.

What is an important factor in selecting aircraft fuses? A) the current exceeds a predetermined value B) the voltage rating should be lower than the max circuit voltage C) Capacity matches the needs of the circuit

C. It is important when aircraft fuses are selected that all the current ratings are appropriate for the circuit protection required.

A series-wound dc electric motor will normally require... A. more current at high RPM than at low RPM B. approx. the same current thoughout its operating range of speed C. more current at low RPM than at High RPM

C. more current at low RPM than at High RPM A series-wound DC motor produces an extremely high starting torque. It uses a large amount of current when it first starts to rotate and when it is operating at slow speeds. The current drops off as the armature speed and the counter EMF builds up.

An ammeter in a battery charging system is for the purpose of indicating the A. amperage available for use B. total amperes being used in the airplane C. rate of current used to change the battery

C. rate of current used to change the battery

Electric circuits are protected from overheating by means of... A) thermocouples B) shunts C) fuses

Electrical circuits are protected from overheating by means of fuses or circuit breakers.

The pole pieces or shoes used in a DC generator are part of the ________ assembly

Field Assembly

A circuit protection device called a current limiter is essentially a slow-blow fuse and is designed to be used in... A) 400 cycle AC circuits B) Heavy power circuits C) Starter-generator circuits

Heavy power circuits

The voltage output of an alternator may be regulated by controlling the... A. speed of the alternator B. voltage output of the DC exciter C. resistance in the rotor windings

The voltage output of an AC alternator is determined by the amount of current flowing in its exciter field. The alternator output voltage may be controlled by varying the output voltage of the DC exciter.

What is a cause of brush arcing??

Low spring tension

Oil canning of the sides of aluminum or steel electrical junction boxes is considered to be A. normal operation in vibration prone areas B. a shorting hazard C. acceptable operation.

Oil canning is the condition of a piece of sheet metal that causes it to snap back and forth when it is distorted or vibrated. If the sides of an electrical junction box oil-can, there is a possibility of some of the wires becoming shorted.

To help minimize radio interference a capacitor will largely eliminate and provide a steady direct current if the capacitor is connected to the generator in.. A)parallel B)series C)series/parallel

PARALLEL

What is a method used for restoring generator field residual magnetism? A) flash the fields B) reseat the brushes C) energize the armature

Residual magnetism may be restored to a generator by flashing its field. To flash the field, momentarily pass direct current from the battery through the generator field coils in the normal direction of current flow.

Aircraft electrical junction boxes located in a fire zone are usually constructed of.. A) asbestos B) cadmium-plated steel C) stainless steel

Stainless Steel

the only practical method of maintain a constant voltage output from an aircraft generator under varying conditions of speed and load is to vary the....

Strength of the magnetic field

When using the voltage drop method of checking circuit resistance, the... A. input voltage must be maintained at a constant value. B.output voltage must be maintained at a constant value. C.input voltage must be varied.

When using the voltage-drop method to check circuit resistance, the input voltage must be maintained at a constant value.

When a diode is checked for an open circuit or a short circuit, it should be.. A. in the circuit B. checked with a milliamp ammeter C. disconnected from the circuit

When a semiconductor diode is checked for an open or a short circuit, it is removed from the circuit and its resistance is checked with an ohmmeter.

When adding a rheostat to a light circuit to control the light intensity, it should be connected in... A) parallel with the light B) series with the light C) series-parallel with the light switch

When installing a rheostat in a light circuit to control the light intensity, install it in series with the light.

Grounding is electrically connecting a conductive object to the primary structure. One purpose of grounding is to.. A) prevent current return paths. B) allow static charge accumulation. C) prevent development of radio frequency potentials.

The most reasonable choice is that electrically grounding a conductive object prevents the development of radio-frequency potential that causes static in a radio. Grounding actually keeps all components at the same electrical potential, so there is no buildup of static charges. Static charges cause sparks to jump and these sparks produce radio-frequency energy.

The primary considerations when selecting electric cable size are... A) current-carrying capacity and allowable voltage drop. B) the voltage and amperage of the load it must carry. C) the system voltage and cable length.

When selecting electrical cable size, you must consider both the current-carrying capacity of the wire and the allowable voltage drop.

The pin section of an AN/MS connector is normally installed on... A. the power supply side of a circuit B. the ground side of a circuit C. either side (makes no difference)

The pin section of an AN/MS connector should be installed on the ground side of a circuit and the socket on the 'hot' side. This arrangement minimizes the possibility of a short between a connector and ground when the connectors are separated.

Electric wiring installed in aircraft without special enclosing means (open wiring) offers the advantages of ease of installation, simple maintenance, and reduced weight. When bundling open wiring, the bundles should.... A) be limited as to the number of cables to minimize damage from a single electrical fault. B) include at least one shielded cable to provide good bonding of the bundle to the airframe. C) be limited to a minimum bend radius of five times the bundle diameter to avoid excessive stresses on the cable insulation.

A) be limited as to the number of cables to minimize damage from a single electrical fault.

The voltage in an ac transformer secondary that contains twice as many loops as the primary will be... A) greater and the amperage less than in the primary B) greater and the amperage greater thin in the primary C) less and the amperage greater than in the primary

A) greater and the amperage less than in the primary

To test generator or motor armature windings for opens.... A) place armature in a growler and connect a 110V test light on adjacent segments; light should light. B) check adjacent segments on commutator with an ohmmeter on the high resistance scale. C) use a 12/24V test light between the armature core segments and the shaft.

A) place armature in a growler and connect a 110V test light on adjacent segments; light should light.

The type of electric wire terminals used for most aircraft applications, in addition to providing good current carrying capabilities, are designed primarily A) to prevent circuit failure due to terminal disconnection B) for uncomplicated and rapid circuit connection and disconnection C) for permanent connection to the circuit

A) to prevent circuit failure due to terminal disconnection Terminals used on aircraft electrical wires must safely carry all of the current the wire can carry. They must also be designed in such a way that they cannot cause a circuit failure by inadvertently disconnecting from the terminal on which they are installed.

What kind of switch should you install in a single wire circuit that required the switch to be manually held in the ON position? A)Single-pole, single-throw (SPST), two-position normally open (NO). B)Single-pole, single-throw (SPST), single-position. C)Single-pole, double-throw (SPDT), single-position normally open (NO).

A)Single-pole, single-throw (SPST), two-position normally open (NO).

A certain switch is described as a single-pole, double-throw switch (SPDT). The throw of a switch indicates the number of A)circuits each pole can complete through the switch. B)terminals at which current can enter or leave the switch. C)places at which the operating device (toggle, plunger, etc.) will come to rest and at the same time open or close a circuit.

A)circuits each pole can complete through the switch.

In aircraft electrical systems, automatic reset circuit breakers... A)should not be used as circuit protective devices. B)are useful where only temporary overloads are normally encountered. C)must be used in all circuits essential to safe operation of the aircraft.

A)should not be used as circuit protective devices. 14 CFR 23.1357 states that each resettable circuit protective device must be so designed that a manual operation is required to restore service after tripping.

Which statement relating to electric wiring is true? A)When attaching a terminal to the end of an electric cable, it should be determined that the strength of the cable-to-terminal joint is at least twice the tensile strength of the cable. B)When attaching a terminal to the end of an electric cable, it should be determined that the strength of the cable-to-terminal joint is at least equal to the tensile strength of the cable itself. C)All electric cable splices should be covered with soft insulating tubing (spaghetti) for mechanical protection against external abrasion.

B)When attaching a terminal to the end of an electric cable, it should be determined that the strength of the cable-to-terminal joint is at least equal to the tensile strength of the cable itself.

When considering an alteration, the criteria upon which the selection of electric cable size should be based are... A)applied voltage and allowable voltage drop B)current carrying capacity and allowable voltage drop C)current carrying capacity and applied voltage

B)current carrying capacity and allowable voltage drop

If the positive field lead between a generator and a generator control panel breaks and is shorted while the engine is running, a voltmeter connected to generator output would indicate... A) zero voltage B)residual voltage C) normal voltage

B)residual voltage If the positive field lead between a generator and its control panel or voltage regulator breaks and shorts to ground while the engine is running, the generator can produce only residual voltage.

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