AIRCRAFT ENGINEERING 12.

What kind of switch should you install in a single

wire circuit that requires the switch to be manually held
in the ON position?
Aircraft Electric Current - Single-pole, single-throw (SPST), two-position
1. If any one generator in a 24-volt dc system shows low normally open (NO).
voltage, the most likely cause is 13. What is the minimum bend radius for an electrical
- An out-of-adjustment voltage regulator wire bundle?

2. Where is the generator rating and performance data - Ten times the outside diameter of the bundle.
located? 14. (1) There are three basic types of dc motors; series,
- Stamped on the generator plate. shunt, and compound.

3. What is required when operating two aircraft ac (2) In the series motor, the field windings, consisting of
generators in parallel? relatively few turns of heavy wire, are connected in
series with the armature winding.
- Frequency and voltage must be equal.
Regarding the above statements,
4. Electrical connectors used in the aircraft assemblies
should meet which of the following specifications? - Both No. 1 and No. 2 are true.

- Military Specifications (MS) 15. A CSD unit that is disconnected in flight, due to a
malfunction such as over-temperature, may be
5. Which of the following are considered circuit- reconnected
protective devices that are used in aircraft electrical
systems? - Only on the ground by maintenance personnel.

- Circuit breakers, fuses, and current limiters. 16. In aircraft electrical systems, automatic reset circuit
breakers
6. How should a coaxial cable be routed?
- Should not be used as circuit protective devices.
- As directly as possible.
17. Which of the following are the major parts of a dc
7. In the American Wire Gauge (AWG) system of motor?
numbers used to designate electrical wire sizes, the
number assigned to a size is related to its 1. Armature assembly

- Cross-sectional area. 2. Field assembly

8. The major advantages of alternating current (AC) over 3. Brush assembly

direct current (DC) is the fact that its current and voltage 4. Commutator
can easily be increased or decreased
5. Pole piece
- By means of a transformer.
6. Rheostat
9. What is a method used for restoring generator field
residual magnetism? 7. End frame

- Flash the fields. - 1, 2, 3, 7

10. What is the color and orientation of the position 18. Circuits that must be operated only in an emergency
lights for navigation on civil airplanes? or whose inadvertent activation could endanger a system
frequently employ
- Left side - red, right side - green, rear aft - white.
- Guarded switches
11. Electric wire terminals for most aircraft applications
must be what type? 19. If it is necessary to use an electrical connector where
it may be exposed to moisture, the mechanic should
- Ring
- Use a special moisture-proof type. R = Resistance per ft = .00644
20. The type of electric wire terminals used for most L = Length of wire
aircraft applications, in addition to providing good
A = Amperes
current carrying capabilities, are designed primarily
- 4V
- To prevent circuit failure due to terminal disconnection.
30. Certain transport aircraft use ac electrical power for
21. How does the magnetic brake used to stop the
all normal operation and battery furnished dc electrical
rotation of an electric motor armature operate?
power for standby emergency use. In aircraft of this type
- A friction brake is applied by a spring and released by a that operates no dc generators, the batteries are kept
magnet. charged by
22. To test generator or motor armature windings for - Rectifiers which use the aircraft’s ac generators as a
opens, source of power.
- Place armature in a growler and connect a 110V test 31. The starting current of a series-wound dc motor, in
light on adjacent segments; the light should light. passing through both the field and armature windings,
produces a
23. A circuit breaker is installed in an aircraft electrical
system primarily to protect the - High starting torque.
- Circuit and should be located as close to the source as 32. What is the advantage of a circuit breaker when
possible. compared to a fuse?
24. The only practical method of maintaining a constant - It is resettable and reusable.
voltage output from an aircraft generator under varying
33. In an AC circuit with no phase lead or lag, which is
conditions of speed and load is to vary the
true?
- Strength of the magnetic field.
- Real power equals apparent power.
25. What is the ratio of turns between the primary coil
34. Integrated drive generators (IDG) employ a type of
winding and the secondary coil winding of a transformer
high output ac generator that utilizes
designed to triple its input voltage?
- A brushless system to produce current.
- Primary will have one-third as many turns as its
secondary. 35. What is the appropriate method for installing pre-
insulated terminal lugs and splices to electric wires?
26. What is the advantage of a current limiter?
- Using a crimping tool to secure the terminal lug.
- It will take overload for a short period.
36. Why are the iron cores of most induction coils
27. If the Integrated Drive Generator (IDG) scavenge oil
laminated?
filter is contaminated with metal, you should
- To reduce the effects of eddy currents.
- Remove and replace the IDG.
37. When adding a rheostat to a light circuit to control
28. The method most often used in overcoming the effect
the light intensity, it should be connected in
of armature reaction is through the use of
- Series with light.
- Interpoles
38. When dc generators are operated in parallel to supply
29. What is the voltage drop for a No. 18 copper wire 50
power for a single load, their controls include an
feet long to carry 12.5 amperes continuous operation?
equalizer circuit to assure that all generators share the
Use the formula VD = RLA load equally. The equalizer circuit operates by
- Increasing the output of the low generator and
decreasing the output of the high generator until they are
VD = Voltage drop
equal.
39. The purpose of a rectifier in an electrical system is to 48. The most common method of regulating the voltage
change output of a compound dc generator is to vary the
- Alternating current to direct current. - Current flowing through the shunt field coils.
40. When using an ohmmeter to check the continuity of 49. A series-wound dc electric motor will normally
a generator field coil, the coil should require
- Show very low resistance if it is a series field coil. - More current at low RPM than at high RPM.
41. The circuit breaker in the instrument lighting system 50. To what depth is the mica insulation between the
protects the commutator bars of a dc generator undercut?
- Wiring from too much current. - Equal to the width of the mica.
42. The pin section of an AN/MS connector is normally 51. Electric wiring installed in aircraft without special
installed on enclosing means (open wiring) offers the advantages of
ease of installation, simple maintenance, and reduced
- The ground side of a circuit.
weight. When bundling open wiring, the bundles should
43. When selecting hardware for attaching bonding
- Be limited as to the number of cables to minimize
connections to an aircraft structure, which of the
damage from a single electrical fault.
following should be considered?
52. An ammeter in a battery charging system is for the
purpose of indicating the
1. Mechanical strength.
- Rate of current used to charge the battery.
2. Allowable power loss.
53. Some electric motors have two sets of field windings
3. Ease of installation. wound in opposite directions so that the

4. Permissible voltage drop. - Motor can be operated in either direction.

5. Amount of current to be carried. 54. Aircraft which operate only ac generators

(alternators) as a primary source of electrical power
6. Type of load (continuous or intermittent). normally provide current suitable for battery charging
- 1, 3, 5 through the use of

44. Which type of dc generator is not used as an airplane - A stepdown transformer and a rectifier.
generator? 55. What is the purpose of the selection of derated
- Series wound switches for known continuous load current
applications?
45. Oil canning of the sides of aluminum or steel
electrical junction boxes is considered to be - To obtain reasonable switch efficiency and service life.

- A shorting hazard. 56. A voltage regulator controls generator voltage by

changing the
46. If the reverse current cutout relay contact points fail
to open after the generator output has dropped below - Resistance of the generator field circuit.
battery potential, current will flow through the generator 57. In troubleshooting an electrical circuit, if an
armature ohmmeter is properly connected across a circuit
- Opposite the normal direction and through the shunt component and some value of resistance is read,
field in the normal direction. - The component has continuity and is not open.
47. Which of the following is not one of the purposes of 58. If a generator is equipped with a vibrator-type
interpoles in a generator? voltage regulator, the actual time the voltage regulator
- Reduce field strength. points remain open
- Depends on the load carried by the generator. 71. If one switch is used to control all navigation lights,
the lights are most likely connected
59. When handling a high voltage capacitor in an
electrical circuit, be sure it - Parallel to each other and in series with the switch.
- Is fully discharged before removing it from the circuit. 72. One advantage of using ac electrical power in
aircraft is
60. Which of the following is most likely to cause
thermal runaway in a nickel-cadmium battery? - Greater ease in stepping the voltage up or down.
- Excessive current draw from the battery. 73. Grounding is electrically connecting a conductive
object to the primary structure. One purpose of
61. The voltage output of an alternator may be regulated
grounding is to
by controlling the
- Prevent the development of radio frequency potentials.
- Voltage output of the dc exciter.
74. When considering an alteration, the criteria upon
62. If several long lengths of electrical cable are to be
which the selection of electric cable size should be based
installed in rigid conduit, the possibility of damage to the
are
cable as it is pulled through the conduit will be reduced
by - Current-carrying capacity and allowable voltage drop.
- Dusting the cable with powdered soapstone. 75. Bonding connections should be tested for
63. A CSD unit drives a generator through the use of - Resistance value
- A variable hydraulic pump and hydraulic motor. 76. During an inspection of an anti-collision light
installation for condition and proper operation, it should
64. A variable hydraulic pump and hydraulic motor.
be determined that
- Capacity matches the needs of the circuit.
- The anti-collision light can be operated independently
65. The commutator of a generator of the position lights.

- Changes alternating current produced in the armature 77. A voltage regulator controls generator output by
into the direct current as it is taken from the armature.
- Varying current flow to generator field coil.
66. How can it be determined if a transformer winding
78. Aluminum wire must be stripped very carefully
has some of its turns shorted together?
because
- The transformer will get hot in normal operation.
- Individual strands will break easily after being nicked.
67. The primary considerations when selecting electric
79. What is the principal advantage of the series-wound
cable size are
dc motor?
- Current-carrying capacity and allowable voltage drop.
- High starting torque.4
68. When necessary during operation, CSD disconnect is
80. Aircraft electrical junction boxes located in a fire
usually accomplished by
zone are usually constructed of
- A switch in the cockpit.
- Stainless steel.
69. How should the splices be arranged if several are to
81. How should a voltmeter be connected?
be located in an electrical wire bundle?
- In parallel with the load.
- Staggered along the length of the bundle.
82. The navigation lights of some aircraft consist of a
70. What type of instrument is used for measuring very
single circuit controlled by a single switch which has an
high values of resistance?
ON position and an OFF position, with no additional
- Megohmmeter. positions possible. This switch is referred to as a
- Single-pole, single-throw (SPST), two-position switch
83. When approved, splices may be used to repair 5. Permissible voltage drop.
manufactured harnesses or installed wiring. The
6. Current carrying capability of the conductor.
maximum number of splices permitted between any two
connectors is 7. Type of load (continuous or intermittent).
- One - 2, 5, 6, 7
84. Electric circuits are protected from overheating by 93. What does a rectifier do?
- Fuses. - Changes alternating current into direct current.
85. What is the frequency of an alternator dependent 94. The voltage in an ac transformer secondary that
upon? contains twice as many loops as the primary will be
- RPM - Greater and the amperage less than in the primary.
86. Residual voltage is a result of magnetism in the 95. A circuit protection device called a current limiter is
essentially a slow-blow fuse and is designed to be used
- Field shoes
in
87. Which motor would be most likely to have an
- Heavy power circuits.
armature brake?
96. If a wire is installed so that it comes in contact with
- Landing light retraction motor
some moving parts, what protection should be given to
88. The overvoltage control automatically protects the the wire?
generator system when excessive voltage is present by
- Pass through conduit.
- Opening the shunt field circuit.
97. Static inverters are electronic devices that change
89. What should be used to protect wires from chafing DC to AC with the
when they must pass through bulkheads, firewalls, ribs,
- Use of an oscillator.
etc.?
98. A certain switch is described as a single-pole,
- Suitable grommet
double-throw switch (SPDT). The throw of a switch
90. How many cycles of ac voltage are produced in a indicates the number of
six-pole alternator of the revolving-field type for each
- Circuits each pole can complete through the switch.
revolution of the rotor?
99. In a generator, what eliminates any possible sparking
- Three
to the brush guides caused by the movement of the
91. What is normally used to bond noncontiguous brushes within the holder?
stainless steel aircraft components?
- The brush pigtail.
- Copper jumpers.
100. What is the most accurate type of frequency-
92. Which of the following factors must be taken into measuring instrument?
consideration when determining the wire size to use for
- Integrated circuit chip having a clock circuit.
an aircraft installation?
101. What protection to wires and cables does conduit
provide when used in aircraft installations?
1. Mechanical strength.
- Mechanical
2. Allowable power loss.
102. An aircraft electrical circuit control relay is
3. Ease of installation.
- An electronically operated switch.
4. Resistance of current return path through the aircraft
103. If the (+) terminal of a voltmeter is connected to the
structure.
(-) terminal of the source voltage and the (-) terminal of
the meter is connected to the (+) terminal of the source 114. To help minimize radio interference, a capacitor
voltage, the voltmeter will read will largely eliminate and provide a steady direct current
if the capacitor is connected to the generator in
- Backwards.
- Parallel
104. What is the maximum amount of time a circuit can
be in operation and still be an intermittent duty circuit? 115. How are generators rated?
- Two minutes - Amperes at rated voltage.
105. In installations where the ammeter is in the 116. Which statement relating to electric wiring is true?
generator or alternator lead, and the regulator system
- When attaching a terminal to the end of an electric
does not limit the maximum current that the generator or
cable, it should be determined that the strength of the
alternator can deliver, the ammeter can be redlined at
cable-to-terminal joint is at least equal to the tensile
what percent of the generator or alternator rating?
strength of the cable itself.
- 100
117. When a diode is checked for an open circuit or a
106. The strength of the core of an electromagnet short circuit, it should be
depends upon the material from which it is constructed
- Disconnected from the circuit.
and which of the following?
118. The poles of a generator are laminated to
- The strength of the core of an electromagnet depends
upon the material from which it is constructed and which - Reduce eddy current losses
of the following.
119. When using the voltage drop method of checking
107. Aircraft fuse capacity is rated in circuit resistance, the
- Amperes - Input voltage must be maintained at a constant value.
108. The inductor-type inverter output voltage is 120. The most common method of attaching a pin or
controlled by the socket to an individual wire in an MS electrical
connector is by
- DC stator field current.
- Crimping
109. CSD driven generators are usually cooled by
121. The nominal rating of electrical switches refers to
- Oil spray
continuous
110. What is the cause of generator brush arcing?
- Current rating with the contacts closed.
- Low spring tension.
122. During ground operation, aircraft generator cooling
111. Major adjustments on equipment such as regulators, is usually accomplished by
contractors, and inverters are best accomplished outside
- An integral fan.
the airplane on test benches with necessary instruments
and equipment. Adjustment procedure should be as 123. Which of the following copper electrical cable sizes
outlined by should be selected to replace a No. 6 aluminum electrical
cable?
- The equipment manufacturer.
- No.6
112. The pole pieces or shoes used in a dc generator are
a part of the 124. If the positive field lead between a generator and a
generator control panel breaks and is shorted while the
- Field assembly
engine is running, a voltmeter connected to generator
113. During an inspection of the terminal strips of an output would indicate
aircraft electrical system, it should be determined that
- Residual voltage.
- The terminal studs are anchored against rotation.
125. A battery-generator system provides direct current. - Lubber line
On installations requiring alternating current from the
6. Cases for electrically operated instruments are made
battery-generator system, it is necessary to have
of
- Inverter
- Iron or steel cases.
126. How is a shunt-wound dc generator connected?
7. If a static pressure system check reveals excessive
- Both fields are shunted across the armature. leakage, the leak(s) may be located by
127. Which of the following should be accomplished in - Isolating portions of the line and testing each portion
the installation of aircraft wiring? systematically starting at the instrument connections.
- Locate the bundle above flammable fluid lines and 8. Fuel flow transmitters are designed to transmit data
securely clamp to structure.
- Electrically
128. Which of the following must be accomplished when
9. The function of a CRT in an EFIS is to
installing an anti-collision light?
- Display alphanumeric data and representations of
- Install a switch independent of the position light
aircraft instruments.
switch.
10. When installing an instrument in an aircraft, who is
129. How can the direction of rotation of a dc electric
responsible for making sure it is properly marked?
motor be changed?
- The mechanic installing the instrument.
- Reverse the electrical connections to either the field or
armature windings. 11. A synchro transmitter is connected to a synchro
receiver
130. One purpose of a growler test is to determine the
presence of - Electrically with wires.
- A shorted armature. 12. A certificated mechanic may perform
- 100-hour inspections of instruments.
AIRCRAFT INSTRUMENTS 13. At sea level, when the average atmospheric pressure
is 14.7 PSI, the barometric pressure is
1. Aircraft temperature thermocouple leads may
- 29.92 inHg
- Not be altered and are designed for a specific
installation. 14. Which of the following instruments will normally
have range markings?
2. Instrument panel shock mounts absorb
- Cylinder head temperature gauge, airspeed indicator
- Low frequency, high-amplitude shocks.
15. An aircraft instrument panel is electrically bonded to
3. When swinging a magnetic compass, the
the aircraft structure to
compensators are adjusted to correct for
- Provide current return paths.
- Magnetic influence deviation
16. A radar altimeter determines altitude by
4. A Bourdon tube instrument may be used to indicate
- Transmitting a signal and receiving back a reflected
1. Pressure
signal.
2. Temperature
17. The operation of an angle-of-attack indicating
3. Position system is based on detection of differential pressure at a
point where the airstream flows in a direction
- 1 and 2
- Not parallel to the true angle of attack of the aircraft.
5. What is the fixed line mark attached to the compass
bowl of a magnetic compass called?
18. Which procedure should you use if you find a 27. Which of the following instrument discrepancies
vacuum-operated instrument glass loose? would require the replacement of the instrument?
- Install another instrument.
19. The maximum deviation (during level flight) 1. Red line missing.
permitted in a compensated magnetic direction indicator
2. Case leaking.
installed on an aircraft certificated under Federal
Aviation Regulation Part 23 is 3. Glass cracked.
- 10 degrees 4. Mounting screws loose.
20. What will be the result if the instrument static 5. Case paint chipped.
pressure line becomes disconnected inside a pressurized
cabin during cruising flight? 6. Leaking at line B nut.

- The altimeter and airspeed indicator will both read low. 7. Will not zero out.

21. How is a flangeless instrument case mounted in an 8. Fogged.

instrument panel? - 2, 3, 7, 8
- By an expanding-type clamp secured to the back of the 28. The function of a symbol generator (SG) in an EFIS
panel and tightened by a screw from the front of the is to
instrument panel.
- Receive and process input signals from aircraft and
22. Turbine engine exhaust gas temperatures are engine sensors and send the data to the appropriate
measured by using display.
- Chromel/alumel thermocouples 29. A turn coordinator instrument indicates
23. When performing the static system leakage check - Both roll and yaw.
required by Section 91.411, the technician utilizes
30. The lubber line on a directional gyro is used to
- Negative pressure.
- Represent the nose of the aircraft.
24. Where may a person look for the information
necessary to determine the required markings on an 31. A certificated mechanic with airframe and
engine instrument? powerplant ratings may
- Not perform repairs to aircraft instruments.

1. Engine manufacturer’s specifications 32. The maximum altitude loss permitted during an
unpressurized aircraft instrument static pressure system
2. Aircraft flight manual integrity check is
3. Instrument manufacturer’s specifications - 100 feet in 1 minute.
4. Aircraft maintenance manual 33. A certificated mechanic with at least an airframe
- 2 or 4 rating may perform

25. A radar altimeter indicates - Inspections and function checks on aircraft

instruments.
- Altitude above ground level.
34. A barometric altimeter indicates pressure altitude
26. Which of the following will cause inaccuracies in a when the barometric scale is set at
magnetic compass that may be compensated for by an
aircraft mechanic? - 29.92” Hg

- Deviation 35. The method of mounting aircraft instruments in their

respective panels depends on the
- Design of the instrument case. 4. A certificated airframe repair station.
36. Data transmitted between components in an EFIS are -3
converted into
44. When flags such as NAV, HDG, or GS are displayed
- Digital signals on an HSI, the indication is
37. The red radial lines on the face of an engine oil - That function is inoperative.
pressure gauge indicates
45. Which of the following operating mechanisms would
- Minimum and/or maximum safe operating limits. be found in a hydraulic pressure gauge?
38. When an aircraft altimeter is set at 29.92” Hg on the - Bourdon tube
ground, the altimeter will read
46. What does a reciprocating engine manifold pressure
- Pressure altitude gauge indicate when the engine is not operating?
39. Instrument static system leakage can be detected by - The existing atmospheric pressure.
observing the rate of change in an indication of the
47. Aircraft instrument value should be marked and
- Altimeter after suction has been applied to the static graduated in accordance with
system to cause a prescribed equivalent altitude to be
- The specific aircraft maintenance or flight manual.
indicated.
48. Which instruments are connected to an aircraft’s
40. Magnetic compass bowls are filled with a liquid to
pitot-static system?
- Dampen the oscillation of the float.
41. The requirements for testing and inspection of
1. Vertical speed indicator
instrument static systems required by Section 91.411 are
contained in 2. Cabin altimeter
- Part 43, appendix E. 3. Altimeter
42. When an unpressurized aircraft’s static pressure 4. Cabin rate-of-change indicator
system is leak checked to comply with the requirements
of Section 91.411, what aircraft instrument may be used 5. Airspeed indicator
in lieu of a pitot-static system tester? - 1, 3, and 5.
49. Which condition would be most likely to cause an
1. Vertical speed indicator excessive vacuum in a vacuum system?

2. Cabin altimeter - Vacuum relief valve improperly adjusted

3. Altimeter 50. Which statement regarding an aircraft instrument

vacuum system is true?
4. Cabin rate-of-change indicator
- Dry-type vacuum pumps with carbon vanes are very
5. Airspeed indicator susceptible to damage from solid airborne particles and
must take in only filtered air.
- Altimeter
51. The green arc on an aircraft temperature gauge
43. Who is authorized to repair an aircraft instrument?
indicates
- The desirable temperature range.
1. A certified mechanic with an airframe rating.
52. Which of the following instrument discrepancies
2. A certificated repairman with an airframe rating. could be corrected by an aviation mechanic?
3. A certificated repair station approved for that class
instrument.
1. Red line missing. - 1, 3, 4, and 5
2. Case leaking. 57. The function of a display controller in an EFIS is to
3. Glass cracked. - Allow the pilot to select the appropriate system
configuration for the current flight situation.
4. Mounting screws loose.
58. What must be done to an instrument panel that is
5. Case paint chipped.
supported by shock mounts?
6. Leaking at line B nut.
- Bonding straps must be installed across the instrument
7. Will not adjust. mounts as a current path.

8. Fogged. 59. How many of the following are controlled by

gyroscopes?
- 1, 4, 5, 6
53. How would an airspeed indicator be marked to show
the best rate-of-climb speed (one engine inoperative)? 1. Attitude indicator.

- A blue radial line. 2. Heading indicator.

54. An aircraft magnetic compass is swung to up-date 3. Turn needle of the turn-and-slip indicator.
the compass correction card when
- Three
- Equipment is added that could affect compass
60. Which instrument condition is acceptable and would
deviation.
not require correction?
55. Which instruments are connected to an aircraft’s
static pressure system only?
1. Red line missing.
2. Case leaking.
1. Vertical speed indicator
3. Glass cracked.
2. Cabin altimeter
4. Mounting screws loose.
3. Altimeter
5. Case paint chipped.
4. Cabin rate-of-change indicator
6. Leaking at line B nut.
5. Airspeed indicator
7. Will not zero out.
- 1 and 3
8. Fogged.
56. Resistance-type temperature indicators using
Wheatstone bridge or ratiometer circuits may be used to -5
indicate the temperatures of which of the following?
61. What marking color is used to indicate if a cover
glass has slipped?
1. Free air - White
2. Exhaust gas temperature 62. Aircraft instrument panels are generally shock-
mounted to absorb
3. Carburetor air
- Low-frequency, high-amplitude shocks.
4. Coolant (engine)
63. (1) Aircraft instruments are color-coded to direct
5. Oil temperature
attention to operational ranges and limitations.
6. Cylinder head temperature
(2) Aircraft instruments range markings are not specified 10. What will a voltmeter read if properly connected
by Title 14 of the Code of Federal Regulations but are across a closed switch in a circuit with electrical power
standardized by aircraft manufacturers. on?
- Zero voltage.
Regarding the statements above, 11. Through which material will magnetic lines of force
pass the most readily?
- Only No. 1 is true.
- Iron
12. What is the total capacitance of a circuit containing
ELECTRICITY FUNDAMENTALS
three capacitors in parallel with capacitances of .02
1. In nickel-cadmium batteries, a rise in cell temperature microfarad, .05 microfarad, and .10 microfarad,
respectively?
- Causes a decrease in internal resistance.
- 0.170 uF
2. When referencing resistance in a parallel DC circuit,
which of the following statements is true? 13. A lead-acid battery with 12 cells connected in series
(no-load voltage = 2.1 volts per cell) furnishes 10
- The total current is equal to the sum of the currents amperes to a load of 2-ohms resistance. The internal
through the individual branches of the circuit. resistance of the battery in this instance is
3. Electrostatic fields are also known as - 0.52 ohm
- Dielectric fields. Formula:
4. Capacitors are sometimes used in dc circuits to Total no-load voltage (V_no-load) = 2.1 volts/cell * 12
- Counteract inductive reactance at specific locations. cells = 25.2 volts.

5. The voltage drop in a circuit of known resistance is V_load = I × R_load = 10 amperes × 2 ohms = 20 volts
dependent on V_internal = V_no-load - V_load = 25.2 volts - 20 volts
- The amperage of the circuit. = 5.2 volts

6. A 1-horsepower, 24-volt dc electric motor that is 80 R_internal = V_internal / I = 5.2 volts / 10 amperes =
percent efficient requires 932.5 watts. How much power 0.52 ohms
will a 1-horsepower, 12-volt dc electric motor that is 75 14. An increase in which of the following factors will
percent efficient require? (Note: 1 horsepower = 746 cause an increase in the inductive reactance of a circuit?
watts)
- Inductance and frequency
- 994.6 watts
15. Which of these will cause the resistance of a
7. What is the purpose of the ground symbol used in conductor to decrease?
electrical circuit diagrams?
- Decrease the length or increase the cross-sectional
- To show that there is a return path for the current area.
between the source of electrical energy and the load.
16. The electrolyte of a nickel-cadmium battery is the
8. In a parallel circuit with four 6-ohm resistors across a lowest when the battery is
24-volt battery, what is the total voltage across resistor-
three (VR3) in the circuit? - In a discharged condition.

- 24 volts 17. A 14-ohm resistor is to be installed in a series circuit

carrying .05 ampere. How much power will the resistor
9. Typical application for zener diodes is as be required to dissipate?
- Voltage regulators. - At least 35 milliwats
18. What determines the amount of current which will 30. What is the operating resistance of a 30-watt light
flow through a battery while it is being charged by a bulb designed for a 28-volt system?
constant voltage source?
- 26 ohms
- The state-of-charge of the battery.
Formula:
19. How many amperes will a 28-volt generator be
I = P / V, which gives us I = 30 / 28 = 1.0714 amps.
required to supply to a circuit containing five lamps in
parallel, three of which have a resistance of 6 ohms each which is R = V / I, which gives us R = 28 / 1.0714 = 26
and two of which have a resistance of 5 ohms each? ohms.
- 25.23 amperes 31. What may result if water is added to a nickel-
cadmium battery when it is not fully charged?
20. Forward biasing of a solid state device will cause the
device to - Excessive spewing is likely to occur during the
charging cycle.
- Conduct
32. In an N-P-N transistor application, the solid state
21. In a P-N-P transistor application, the solid state
device is turned on when the
device is turned on when the
- Base is positive with respect to the emitter.
- Base is negative with respect to the emitter.
33. The electrolyte of a nickel cadmium battery is
22. .002KV equals
highest when the battery is
- 2.0 volts
- In fully charged condition.
23. What unit is used to express electrical power?
34. Convert farads to picofarads by:
- Watt
- Multiplying farads by 10 to the power of 12
24. Which of the following is commonly used as a
35. When referring to an electrical circuit diagram, what
rectifier in electrical circuits?
point is considered to be at zero voltage?
- Diodes
- The ground reference.
25. The opposition offered by a coil to the flow of
36. The correct way to connect a test voltmeter in a
alternating current is called (disregard resistance)
circuit is
- Inductive reactance
- In parallel with a unit.
26. A fully charged lead-acid battery will not freeze until
37. A 12-volt electric motor has 1,000 watts input and 1
extremely low temperatures are reached because
hp output. Maintaining the same efficiency, how much
- Most of the acid is in the solution. input power will a 24-volt, 1 hp electric motor require?
(Note: 1 hp = 746 watts)
27. Which requires the most electrical power? (Note: 1
horsepower = 746 watts) - 1,000 watts
- A 1/5-horsepower, 24-volt motor which is 75 percent Formula:
efficient.
Input Power (P) = Output Power (P) x Voltage (V)
28. What factors strengthen a coil inductor?
Input Power (P) = 746 watts x 24 volts
- Adding coils close together.
Input Power (P) = 17,904 watts
29. Which of the following logic gates will provide an
38. Which of the following statements is/are generally
active high out only when all inputs are different?
true regarding the charging of several aircraft batteries
- XOR together?
1. Batteries of different voltages (but similar capacities) - Two lights requiring 3 amperes each in a 24-volt
can be connected in series with each other across the parallel system.
charger, and charged using the constant current method.
48. Which is correct in reference to electrical resistance?
2. Batteries of different ampere-hour capacity and same
- If one of three bulbs in a parallel lighting circuit is
voltage can be connected in parallel with each other
removed, the total resistance of the circuit will become
across the charger, and charged using the constant
greater.
voltage method.
49. In a parallel circuit with three 6-ohm resistors across
3. Batteries of the same voltage and same ampere-hour
a 12-volt battery, what is the total current (It) value in
capacity must be connected in series with each other
the circuit?
across the charger, and charged using the constant
current method. - 6 amps
- 1 and 2 50. The potential difference between two conductors
which are insulated from each other is measured in
39. What happens to the current in a voltage step-up
transformer with a ratio of 1 to 4? - Volts
- The current is stepped down by a 1 to 4 ratio. 51. A cabin entry light of 10 watts and a dome light of 20
watts are connected in parallel to a 30-volt source. If the
40. When inductors are connected in series in a circuit,
voltage across the 10-watt light is measured, it will be
the total inductance is (where the magnetic fields of each
inductor do not affect the others). - Equal to the voltage across the 20-watt light.
(Note: L(T) = L(1) + L(2) + L(3)...) 52. A circuit has an applied voltage of 30 volts and a
load consisting of a 10-ohm resistor in series with a 20-
- Equal to the sum of the individual inductances.
ohm resistor. What is the voltage drop across the 10-ohm
41. When different rated capacitors are connected in resistor?
parallel in a circuit, the total capacitance is (Note: C(T)
- 10 volts
= C(1) + C(2) + C(3)…)
53. If three resistors of 3 ohms, 5 ohms, and 22 ohms are
- Equal to the sum of all the capacitances.
connected in series in a 28-volt circuit, how much
42. When calculating power in a reactive or inductive ac current will flow through the 3-ohm resistor?
circuit, the true power is
- 0.93 ampere
- Less than the apparent power.
54. What is the total capacitance of a certain circuit
43. Which effect does not apply to the movement of containing three capacitors with capacitances of .25
electrons flowing in a conductor? microfarad, .03 microfarad, and .12 microfarad,
respectively? (Note: C(T) = C(1) + C(2) + C(3))
- Static energy
- .4 µF
44. Which is correct concerning a parallel circuit?
55. The method used to rapidly charge a nickel-cadmium
- Total resistance will be smaller than the smallest
battery utilizes
resistor.
- Constant voltage and varying current
45. What is the basic unit of electrical quantity?
56. The basis for transformer operation in the use of
- Coulomb
alternating current is mutual
46. A thermal switch, or thermal protector, as used in an
- Inductance
electric motor, is designed to
57. The term that describes the combined resistive forces
- Open the circuit in order to allow cooling of the motor.
in an ac circuit is
47. Which requires the most electrical power during
- Impedance
operation? (Note: 1 hp = 746 watts)
58. Transfer of electric energy from one circuit to 69. Which condition is an indication of improperly
another without the aid of electrical connections torqued cell link connections of a nickel-cadmium
battery?
- Is called induction
- Heat or burn marks on the hardware.
59. The presence of any small amount of potassium
carbonate deposits on the top of nickel-cadmium battery 70. The end-of-charge voltage of a 19-cell nickel-
cells in service is an indication of cadmium battery, measured while still on charge,
- Normal operation - Depends upon its temperature and the method used for
charging.
60. What does the letter Q symbolize when measuring
electrical charge? 71. Which statement regarding the hydrometer reading
of a lead-acid storage battery electrolyte is true?
- Coulomb
- The hydrometer reading does not require a temperature
61. Which of the following best describes the
correction if the electrolyte temperature is 80° F.
contributing factors to thermal runaway in a nickel-
cadmium battery installed in an aircraft? 72. When a charging current is applied to a nickel-
cadmium battery, the cells emit gas
- Low internal resistance intensified by high cell
temperatures and a high current discharge/charge rate in - Toward the end of the charging cycle.
a constant potential (voltage) charging system.
73. Which of the following best describes the operating
62. Convert farads to microfarads by principle in a nickel-cadmium battery installed in an
aircraft?
- Multiplying farads by 10 to the power of 6.
- To completely charge a nickel-cadmium battery, some
63. A 24-volt source is required to furnish 48 watts to a
gassing must take place; thus, some water will be used.
parallel circuit consisting of four resistors of equal value.
What is the voltage drop across each resistor? 74. What is the opposition to the flow of the AC
produced by a magnetic field with generated back
- 24 volts
voltage (EMF) called?
64. If electrolyte from a lead-acid battery is spilled in the
- Inductive reactance.
battery compartment, which procedure should be
followed? 75. Which term means .001 ampere?
- Apply sodium bicarbonate solution to the affected area - Milliampere
followed by a water rinse.
76. During discharge, nickel-cadmium batteries will
65. How can the state-of-charge of a nickel-cadmium show a lower liquid level than when at full charge
battery be determined? because
- By a measured discharge. - The electrolytes become absorbed into the plates.
66. The working voltage of a capacitor in an ac circuit 77. Unless otherwise specified, any values given for
should be current or voltage in an ac circuit are assumed to be
- At least 50% greater than the highest applied voltage. - Effective values.
67. If each cell, connected in series, equals 2 volts, how 78. What is the likely result of servicing and charging
would a 12-cell lead acid battery be rated? nickel-cadmium and lead acid batteries together in the
same service area?
- 24 volts
- Contamination of both types of batteries.
68. In an ac circuit, the effective voltage is
79. The amount of electricity a capacitor can store is
- Less than the maximum instantaneous voltage.
directly proportional to the
- Plate area and inversely proportional to the distance - Generator output voltage will increase.
between the plates.
9. The generating system of an aircraft charges the
80. The purpose of providing a space underneath the battery by using
plates in a lead acid battery’s cell container is to
- Constant voltage and varying current
- Prevent sediment buildup from contacting the plates
10. How many basic types of circuit breakers are used in
and causing a short circuit.
powerplant installation electrical systems?
- Three
ENGINE ELECTRIC CURRENT
Explanation: Thermal, Electronic and Magnetic
1. (1) Electrical wires larger than 10 gauge use
11. When the starter switch to the aircraft gas turbine
uninsulated terminals.
engine starter-generator is energized and the engine fails
(2) Electrical wires smaller than 10 gauge use to rotate, one of the probable causes would be the
uninsulated terminals.
- Starter solenoid is defective.
12. What speed must an eight-pole ac generator turn to
Regarding the above statements, produce 400-Hertz ac?
- Only No. 1 is true. - 6,000 RPM
2. The part of a dc alternator power system that prevents Formula: Speed (RPM) = Frequency (Hz) x 120 /
reverse flow of current from the battery to the alternator Number of Poles
is the
13. The stationary field strength in a direct current
- Rectifier generator is varied
3. How many hours will a 140 ampere-hour battery - According to the load requirements.
deliver 15 amperes?
14. Bonding jumpers should be designed and installed in
- 9.33 hours such a manner that they
4. When selecting an electrical switch for installation in - Provide a low electrical resistance in the ground circuit.
an aircraft circuit utilizing a direct current motor,
15. Aircraft that operate more than one generator
- A derating factor should be applied. connected to a common electrical system must be
provided with
5. The constant current method of charging a ni-cad
battery - Individual generator switches that can be operated from
the cockpit during flight.
- Is the method most effective in maintaining cell
balance. 16. If a generator is malfunctioning, its voltage can be
reduced to residual by actuating the
6. What is the smallest terminal stud allowed for aircraft
electrical power systems? - Generator master switch
- No. 10 17. A certain direct current series motor mounted within
an aircraft draws more amperes during start than when it
7. The maximum number of terminals that may be
is running under its rated load. The most logical
connected to any one terminal stud in an aircraft
conclusion that may be drawn is
electrical system is
- The condition is normal for this type of motor.
- Four
18. As the generator load is increased (within its rated
8. If the points in a vibrator-type voltage regulator stick
capacity), the voltage will
in the closed position while the generator is operating,
what will be the probable result?
- Remain constant and the amperage output will 29. What is the frequency of most aircraft alternating
increase. current?
19. A high surge of current is required when a dc electric - 400 Hertz
motor is first started. As the speed of the motor
30. What are two types of ac motors that are used to
increases,
produce a relatively high torque?
- The counter emf builds up and opposes the applied
- Three-phase induction and capacitor start
emf, thus reducing the current flow through the
armature. 31. The resistance of the current return path through the
aircraft is always considered negligible, provided the
20. Which Federal Aviation Regulation requirement
prevents the use of automatic reset circuit breakers? - Structure is adequately bonded.
- 14 CFR Part 23 32. Electric motors are often classified according to the
method of connecting the field coils and armature.
21. What is a basic advantage of using ac for electrical
Aircraft engine starter motors are generally of which
power for a large aircraft?
type?
- AC systems operate at higher voltage than dc systems
- Series
and therefore use less current and can use smaller and
lighter weight wiring. 33. According to the electron theory of the flow of
electricity, when a properly functioning dc alternator and
22. Starter brushes should be replaced when they are
voltage regulating system is charging an aircraft’s
worn down to
battery, the direction of current flow through the battery
- One-half of the original length.
- Is into the negative terminal and out the positive
23. A typical barrier type aircraft terminal strip is made terminal.
of
34. What type of lubricant may be used to aid in pulling
- Paper-base phenolic compound electrical wires or cables through conduits?
24. The maximum allowable voltage drop between the - Soapstone talc
generator and the bus bar is
35. When does current flow through the coil of a
- 2% of the regulated voltage. solenoid-operated electrical switch?
25. When installing an electrical switch, under which of - Continually, as long as the control circuit is complete.
the following conditions should the switch be derated
36. Which of the following Federal Aviation Regulations
from its nominal current rating?
require that all aircraft using fuses as the circuit
- Direct-current motor circuits. protective devices carry ‘one spare set of fuses, or three
spare fuses of each kind required’?
26. Which of the following is regulated in a generator to
control its voltage output? - 14 CFR Part 91
- The strength of the field. 37. Alternators (ac generators) that are driven by a
constant-speed drive (CSD) mechanism are used to
27. One way that the automatic ignition relight systems
regulate the alternator to a constant
are activated on gas turbine engines is by a
- Hertz output
- Drop in compressor discharge pressure.
38. What device is used to convert alternating current,
28. Generator voltage will not build up when the field is
which has been induced into the loops of the rotating
flashed and solder is found on the brush cover plate.
armature of a dc generator, to direct current?
These are most likely indications of
- A commutator.
- An open armature.
39. What is the ampere-hour rating of a storage battery
that is designed to deliver 45 amperes for 2.5 hours?
- 112.5 ampere-hour 51. Which of the following aircraft circuits does NOT
contain a fuse/circuit breaker?
40. Why is a constant-speed drive used to control the
speed of some aircraft engine-driven generators? - Starter circuit
- So that the frequency of the alternating current output 52. Why is it unnecessary to flash the field of the exciter
will remain constant. on a brushless alternator?
41. How are the rotor windings of an aircraft alternator - Permanent magnets are installed in the main field
usually excited? poles.
- By a variable direct current. 53. What is the maximum number of bonding jumper
wires that may be attached to one terminal grounded to a
42. When installing electrical wiring parallel to a fuel
flat surface?
line, the wiring should be
- Four
- Above the fuel line.
54. Electrical circuit protection devices are installed
43. ON-OFF two position engine electrical switches
primarily to protect the
should be installed
- Wiring
- So the ON position is reached by a forward or upward
motion. 55. (1) Alternators are rated in volt-amps, which is a
measure of the apparent power being produced by the
44. A term commonly used when two or more electrical
generator.
terminals are installed on a single lug of a terminal strip
is (2) Alternating current has the advantage over direct
current in that its voltage and current can easily be
- Stacking
stepped up or down.
45. In order to reduce the possibility of ground shorting
the circuits when the connectors are separated for
maintenance, the AN and MS electrical connectors Regarding the above statements,
should be installed with the
- Both No. 1 and No. 2 are true.
- Pin section on the ground side of the electrical circuit.
56. What type of electric motor is generally used with a
46. Aircraft wire size is determined by using the direct-cranking engine starter?
- Wire gauge - Direct current, series-wound motor
47. The time/current capacities of a circuit breaker or 57. (1) Electrical circuit protection devices are rated
fuse must be based on the amount of current that can be carried
without overheating the wiring insulation.
- Below those of the associated conductor.
(2) A ‘trip-free’ circuit breaker makes it impossible to
48. As the flux density in the field of a dc generator
manually hold the circuit closed when excessive current
increases and the current flow to the system increases,
is flowing.
the
- Force required to turn the generator increases.
Regarding the above statements,
49. Upon what does the output frequency of an ac
generator (alternator) depend? - Both No. 1 and No. 2 are true.
- The speed of rotation and the number of field poles. 58. Which Federal Aviation Regulation specifies that
each resettable circuit protective device requires a
50. Aircraft copper electrical wire is coated with tin,
manual operation to restore service after the device has
silver, or nickel in order to
interrupted the circuit?
- Prevent oxidization.
- 14 CFR Part 23
59. Aircraft electrical wire is manufactured in sizes FIRE DEFENSE COMPONENTS
according to a standard known as
1. The types of fire-extinguishing agents for aircraft
- American Wire Gauge (AWG) interior fires are
60. The reason for flashing the field in a generator is to - water, carbon dioxide, dry chemicals, and halogenated
hydrocarbons.
- Restore residual magnetism to the field frame.
2. What method is used to detect the thermal discharge
61. (1) Most modern aircraft use circuit breakers rather
of a built-in fire-extinguisher system?
than fuses to protect their electrical circuits.
- A rupture of the red plastic disk in the thermal
(2) Federal Aviation Regulations Part 23 requires that all
discharge line.
electrical circuits incorporate some form of circuit
protective device. 3. A contaminated carbon monoxide portable test unit
may be returned to service by
- Removing the indicating element and installing a new
Regarding the above statements,
indicating element.
- Only No. 1 is true.
4. The proper fire-extinguishing agent to use on an
62. Arcing at the brushes and burning of the commutator aircraft brake fire is
of a motor may be caused by
- Dry powder chemical
- Weak brush springs
5. Which fire-extinguishing agent is considered to be the
63. What is the purpose of a reverse-current cutout least toxic?
relay?
- Bromotrifluoromethane (Halon 1301)
- It opens the main generator circuit whenever the
6. In some fire-extinguishing systems, evidence that the
generator voltage drops below the battery voltage.
system has been intentionally discharged is indicated by
64. What is used to polish commutators or slip rings? the absence of a

- Double-0 sandpaper - Yellow disk on the side of the fuselage.

65. When a 28 volt, 75 ampere generator is installed on 7. In reference to aircraft fire-extinguishing systems,
an aircraft, an electrical load analysis ground check is
performed and it is determined that the battery is
furnishing 57 amperes to the system, with all electrical (1) during removal or installation, the terminals of
equipment operating. This indicates discharge cartridges should be grounded or shorted.
- The load will be within the generator load limit. (2) before connecting cartridge terminals to the electrical
system, the system should be checked with a voltmeter
66. What precaution is usually taken to prevent
to see that no voltage exists at the terminal connections.
electrolyte from freezing in a lead acid battery?
- Keep the battery fully charged.
Regarding the above statements,
67. Electrical switches are rated according to the
- Both No. 1 and No. 2 are true.
- Voltage and the current they can control.
8. What occurs when a visual smoke detector is
68. The most effective method of regulating aircraft
activated?
direct current generator output is to vary, according to
the load requirements, the - A lamp within the indicator illuminates automatically.
- Strength of the stationary field. 9. On a periodic check of fire-extinguisher containers,
the pressure was not between minimum and maximum
limits. What procedure should be followed?
- Replace the extinguisher container. 19. When used in fire-detection systems having a single
indicator light, thermal switches are wired in
10. In what area of aircraft would you find a carbon
monoxide detector? - Parallel with each other and in series with the light.
- Cabin and cockpit 20. A fire-extinguisher container can be checked to
determine its charge by
11. Smoke in the cargo and/or baggage compartment of
an aircraft is commonly detected by which instrument? - Weighing the container and its contents.
- Photoelectric cell 21. If a fire extinguisher cartridge is removed from a
discharge valve, it should be
12. Which fire-detection system measures temperature
rise compared to a reference temperature? - Used only on the original discharge valve assembly.
- Thermocouple 22. A thermocouple in a fire-detection system causes the
warning system to operate because
13. Which of the following are fire precautions which
must be observed when working on an oxygen system? - It generates a small current when heated.
23. A squib, as used in a fire-protection system, is a
1. Display ‘No Smoking’ placards. - Device for causing the fire-extinguishing agent to be
released.
2. Provide adequate fire-fighting equipment.
24. Built-in aircraft fire-extinguishing systems are
3. Keep all tools and oxygen servicing equipment free
ordinarily charged with
from oil or grease.
- Halogenated hydrocarbons and nitrogen
4. Avoid checking aircraft radio or electrical systems.
25. Smoke detection instruments are classified by their
- 1, 2, 3, and 4
method of
14. The thermal switches of a bimetallic thermal-switch
- Detection.
type fire-detection (single-loop) system are heat-
sensitive units that complete circuits at a certain 26. The most common cause of false fire warnings in
temperature. They are connected in continuous-loop fire detection systems is
- Parallel with each other, but in series with the indicator - Dents, kinks, or crushed sensor sections.
lights.
27. Why does the Fenwal fire-detection system use spot
15. When air samples contain carbon monoxide, portable detectors wired parallel between two separate circuits?
carbon monoxide detectors containing yellow silica gel
- A short may exist in either circuit without causing a
will turn which color?
false fire warning.
- Green
28. What is the color code for fire-extinguisher lines?
16. The thermocouple fire-warning system is activated
- Brown
by a
29. Light refraction smoke detectors are activated when
- Rate-of-temperature rise.
the detector
17. Maintenance of fire-detection systems includes the
- Senses light reflected from smoke particles passing
- Replacement of damaged sensing elements. through a chamber.
18. Smoke detectors that use a measurement of light 30. A carbon dioxide (CO(2)) hand-held fire extinguisher
transmissibility in the air are called may be used on an electrical fire if the
- Photoelectrical devices - Horn is nonmetallic.
SURFACE FINISH & WOOD PARTS 11. Which statement is true regarding paint system
compatibility?
1. Any wooden member that has been overstressed is
subject to which type of failure? - Old wash primer coats may be overcoated directly with
epoxy finishes.
- Compression
12. When dope-proofing the parts of the aircraft
2. What is likely to occur if an unhydrated wash primer
structure that come in contact with doped fabric, which
is applied to unpainted aluminum and then about 30 to
of the following provide an acceptable protective
40 minutes later a finish topcoat, when the humidity is
coating?
low?
- Corrosion
1. Aluminum foil.
3. The determining factor(s) for the selection of the
correct weight of textile fabric to be used in covering 2. Resin impregnated cloth tape.
any type of aircraft is the
3. Any one-part type metal primer.
- Speed of the aircraft and the maximum wing loading.
4. Cellulose tape.
4. Laminated wood is sometimes used in the
- 1 and 4
construction of highly stressed aircraft components. This
wood can be identified by its 13. What is the usual cause of runs and sags in aircraft
finishes?
- Parallel grain construction
- Too much material applied in one coat.
5. Which defect in aircraft finishes may be caused by
adverse humidity, drafts, or sudden changes in 14. When and how is finishing tape applied on a fabric-
temperature? covered aircraft?
- Blushing - Doped on after the first or second coat of dope.
6. The best method of repair for a fabric-covered surface 15. Finishing tape (surface tape) is used for what
which has an L-shaped tear, each leg of which is purpose?
approximately 14 inches long, is to
- To provide additional wear resistance over the edges of
- The best method of repair for a fabric-covered surface fabric forming structures.
which has an L-shaped tear, each leg of which is
approximately 14 inches long, is to 16. The I-beam wooden spar is routed to

7. Which type of coating typically includes phosphoric - Reduce weight

acid as one of its components at the time of application? 17. Before applying a protective coating to any
- Wash primer unpainted clean aluminum, you should

8. Which properly applied finish topcoat is the most - Avoid touching the surface with bare hands.
durable and chemical resistant? 18. Which of the following is a hazard associated with
- Polyurethane sanding on fabric-covered surfaces during the finishing
process?
9. Compression failures in wood aircraft structures are
characterized by buckling of the fibers that appear as - Static electricity buildup.
streaks on the surface 19. If registration numbers are to be applied to an
- At right angles to the grain. aircraft with a letter height of 12 inches, what is the
minimum space required for the registration mark
10. Where is information found concerning acceptable N1683C?
species substitutions for wood materials used in aircraft
repair?
- AC 43.13-1B Note:
 - No external bracing.
2/3 x height = character width 31. Which statement concerning wood decay is correct?
1/6 x height = width for 1 - Any form or amount of decay is not permitted.
1/4 x 2/3 height = spacing 32. When patching a plywood skin, abrupt changes in
cross-sectional areas which will develop dangerous
1/6 x height = stroke or line width
stress concentration should be avoided by using
- 52 inches
- Circular or elliptical patches
20. What is used to slow the drying time of some
33. If masking tape is applied to an aircraft such as for
finishes and to prevent blush?
trim spraying, and is left on for several days and/or
- Retarder exposed to heat, it is likely that the tape will

21. Moisture, mildew, chemicals, and acids have no - Cure to the finish and be very difficult to remove.
effect on
34. The strength classification of fabrics used in aircraft
- Glass fabric covering is based on

22. The strength of a well-designed and properly - Tensile strength

prepared wood splice joint is provided by the
35. When testing the strength of Grade A cotton fabric
- Glue covering an aircraft that requires only intermediate
grade, the minimum acceptable strength the fabric must
23. A correct use for acetone is to have is
- Remove grease from fabric - 70 percent of the original strength for intermediate
24. How many fabric thicknesses will be found in a fabric.
French-fell seam? 36. Fungisid and mildewcide additives are important for
- Four fabric covered aircraft, such as

25. Pin knot clusters are permitted in wood aircraft - Cotton and linen
structure provided 37. A faint line running across the grain of a wood spar
- They produce a small effect on grain direction. generally indicates

26. Which of the following conditions will determine - Compression failure

acceptance of wood with mineral streaks? 38. Aluminum pigment in dope is used primarily to
- Careful inspection fails to reveal any decay - Reflect ultraviolet from the fabric.
27. Glue deterioration in wood aircraft structure is 39. Fungicidal dopes are used in aircraft finishing as the
indicated
- First coat to prevent fabric rotting and are applied thin
- When a joint has separated and the glue surface shows enough to saturate the fabric.
only the imprint of the wood with no wood fibers
clinging to the glue. 40. In cases of elongated bolt holes in a wood spar or
cracks in the vicinity of boltholes,
28. Fabric rejuvenator is used to
- A new section of spar should be spliced in or the spar
- Restore the condition of dope coatings. replaced entirely.
29. Which statement about wood decay is correct? 41. Laminated wood spars may be substituted for solid
- Decay is not acceptable in any form or amount. rectangular wood spars

30. The cantilever wing uses - If the same quality wood is used in both.
42. (1) Machine-sewn seams in aircraft covering fabrics
may be of the folded-fell or French-fell types.
(2) A plain lapped seam is never permissible.

Regarding the above statements,

- Only No. 1 is true.
43. What is likely to occur if a hydrated wash primer is
applied to unpainted aluminum and then about 30 to 40
minutes later a finish topcoat, when the humidity is low?
- A glossy, blush-free finish.