2A656 VOL 2 Q&A

  1. What type of screwdriver fits cross-recessed screws?
    a. A cross-point screwdriver.
  2. What type of screwdriver should you use if there’s not enough room for a standard screwdriver?
    a. An offset screwdriver.
  3. How do you know whether you’re using the right size screwdriver?
    a. The blade will fit the screw slot snugly.
  4. What type of hammer is most widely used by mechanics?
    a. Ball-peen hammer.
  5. Match the jobs in column A with the plier’s usage in column B. Column B items may be used more than once.
    • “Column B” (a)Don’t use pliers; use another tool, (b)Use adjustable water pump pliers, (c)Use vise grip pliers, (d)Use diagonal cutting pliers, (e)Use long-nose pliers.
    • “Column A” b(1)Gripping odd-shaped objects, d(2)Cutting soft wire, a(3)Loosening nuts, e(4)Making delicate adjustment, c(5) Holding parts securely while you are working on them, d(6)Clipping cotter pins, e(7)Forming loops in wire, a(8) Tightening bolts, d(9) Replacing cotter pins
  6. Why should you pull a wrench, rather than pushing it?
    a. To keep from injuring your hand.
  7. Which wrench is good for loosening and tightening odd-size nuts and bolts?
    a. An adjustable-jaw wrench.
  8. Should you use a speed handle on the socket wrench to break nuts loose?
    a. No, use a hinge handle.
  9. What type of file should you use on hard steel?
    a. Start with a smooth file and finish with a dead-smooth file.
  10. List three types of files, and when they are used.
    a. (1)A mill file used on flat surfaces, (2)Triangular file used for removing metal from inside corners, (3)A round (rattail) file for enlarging round holes.
  11. Why do you use thickness gauges?
    a. To measure clearance between two objects.
  12. Why might you use a thread gauge?
    a. When measuring the number of threads per inch when rethreading nuts, or to identify and order the right replacement part.
  13. With what kind of torque wrench would you torque a clamp to 25 inch-pounds?
    a. A 1/4-inch drive, breakaway torque wrench (set at 25 inch-pounds).
  14. How do you reduce the setting on a torque wrench?
    a. Turn the handle counterclockwise.
  15. How often must a torque wrench be verified?
    a. Every 60 calendar days.
  16. In preparing a torque wrench for storage, what do you set the scale on?
    a. The lowest usable setting.
  17. How do you identify a section of tubing in the oxygen system?
    a. With green coding tape labeled “breathing oxygen”.
  18. What kind of fitting do you use to route tubing through a bulkhead?
    a. Bulkhead fitting.
  19. How are special bolts usually identified?
    a. By the letter S on the bolt head.
  20. What should you consider in selecting the shank and grip length of a bolt?
    a. Check for proper diameter, length, and good mechanical fit.
  21. What inspection should you make on a nonmetallic self-locking nut before it’s reused?
    a. Make sure the locking insert hasn’t lost its locking friction or become brittle.
  22. What safetying device is used with a castle nut?
    a. Cotter pin.
  23. When can you use single-strand safety wiring?
    a. When the bolts or screws are closely grouped.
  24. How do you secure an AN connector plug?
    a. Safety wire it at installation with at least 0.020-inch wire.
  25. How do you safety a V-band clamp?
    a. Run a double strand through the clamp, and twist the ends together.
  26. Why does aircraft wiring have many small strands of wire instead of a solid core?
    a. To make the wire more flexible.
  27. What methods are authorized marking wires and cables?
    a. Direct marking and Indirect marking.
  28. Why are aircraft wires numbered?
    a. To identify the circuit it belongs to, its gauge size, and other information necessary to relate it to a wiring diagram.
  29. What must wires and wire groups be protected from?
    a. (1)Chafing or abrasion, (2)High temperature, (3)Possible use as a handhold or as support for equipment of personal belongings, (4) Damage from cargo being stored or shifted, (5)Damage from personnel moving about within the aircraft, (6)Damage from battery acid or fumes, (7)Abrasion in the wheel well areas.
  30. What’s the maximum distance between ties on a wire bundle?
    a. Twelve inches.
  31. What is the advantage of flat tape over round cord?
    a. Tape won’t cut into wire bundles.
  32. What are the two types of terminals?
    a. Soldered and solderless.
  33. Why shouldn’t terminal eyelets be enlarged?
    a. It reduces the amount of material and thus its current-carrying capabilities.
  34. How are terminal lugs secured to terminal studs?
    a. So that any movement of the lug will cause tightening.
  35. What method of splicing is most widely used?
    a. Crimp-on method.
  36. What is the purpose of an electrical connector?
    a. To join segments of electrical circuits and simplify maintenance by providing a means of quick removal and installation of electrical equipment.
  37. Which component of the connector is the fixed part?
    a. The receptacle.
  38. What ensures proper mating of the connector plug and receptacle?
    a. A key and keyway arrangement in the barrel.
  39. What information gives the class, size and type of connector?
    a. The part number stamped on the barrel.
  40. How much will thermofit shrink when heated with the heat-shrinking tool?
    a. At least half of its original diameter.
  41. What type of material is used in fabricating boots, end caps, sleeving, and tubing?
    a. Thermofit material.
  42. What is EMP Cable and what is its purpose?
    a. It is a compact wire bundle with self-contained wire assemblies. It provides a barrier to electrostatic interference. You use it to interconnect electrical and electronic EMP hardened components.
  43. In repairing or replacing bonds or grounds, what must you consider with regard to the hardware?
    a. The replaced hardware must be of the same type of hardware as that removed.
  44. What is the maximum ohm value for a bonding or grounding jumper connection?
    a. No more than 0.1 ohm.
  45. What is the purpose of shielded wire?
    a. To provide a barrier to electrostatic interference with instruments, radios, etc.
  46. What kind of solder is preferred for connections in electronics circuits?
    a. Rosin-core solder with a higher tin alloy and shorter range of plasticity.
  47. What type of solder is preferred when temperature limitations are critical?
    a. 63/37 solder.
  48. What is the advantage of a soldered connection over one that’s wired or bolted?
    a. Bolted or wired connections never make good electrical contact because of the insulating film on the surface of the metals. Soldered connections, on the other hand behave life one solid metal.
  49. What is the purpose of flux?
    a. It’s used to remove the oxide film from the surface of metals and keep it removed during soldering.
  50. Why should you avoid corrosive types of flux in soldering electrical connections?
    a. In time it will eat through the connection and create a high-resistance circuit.
  51. What determines whether you need a soldering iron or a soldering gun for the job?
    a. Use a soldering gun for heavy heating when there’s no chance of damage to sensitive electronic components.
  52. Before replacing the soldering iron tip, what must you do?
    a. Clean the barrel and then file the tip to the required shape using a flat, fine, single-cut file.
  53. Why should copper tips be filed cold?
    a. A tip that’s filed hot will oxidize quickly and cause tinning to be difficult.
  54. When a soldering iron is not being used to apply heat, why should it not be kept clean of solder?
    a. A pool of solder on the tip will reduce surface pitting and oxidation and will increase the time between tip rework.
  55. How can thermal strippers prevent blistering or excessive melting of insulation?
    a. By having a controlled-heat output.
  56. When can you use needle-nose pliers as a bending tool?
    a. When the jaw tips are covered with copper tubing.
  57. What can you use to clean gold plating from printed circuit pads?
    a. A white rubber ink eraser.
  58. What keeps you from being tempted to grab a falling work piece?
    a. Work pieces are securely supported before you start.
  59. What should you do to keep from being struck in the eye by pieces cut from wire strands?
    a. Wearing of proper eye protection.
  60. Why shouldn’t you wear watches or rings while you’re soldering?
    a. A splatter of solder can get caught under the watch or ring and cause a severe burn.
  61. State five safeguards against being burned by a hot soldering iron. A
    a. Any five of the following: (1)Make sure that the soldering iron plug is free of wire strands or metal, (2)Don’t remove the tip from a hot soldering iron; this can damage the threads or set screws on the tip, (3)When tinning, hold the iron well away from your face, and don’t test the heat by holding the iron near your face. Test it with solder, holding it away from your body to avoid being splattered with solder or flux particles, (4)Don’t try to flip molten solder from a soldering iron tip; use a rag, damp sponge, or canvas pad to wipe it off, (5)Look at the soldering iron whenever you pick it up to avoid contact with the barrel, (6)Don’t let the cord drag on the floor when you carry a hot electric soldering iron. It could catch on equipment and drag the iron through your hand, (7)Always place a soldering iron in its holder or another safe place when it’s not in use, and don’t leave it connected when you leave the area, (8)Wash your hands thoroughly before eating or smoking. Most fluxes contain materials that are a health hazard if you ingest them.
  62. How is the insulation clearance of a wire determined?
    a. By the diameter of the wire (including insulation).
  63. What unsatisfactory condition would you look for in stranded wire after the insulation has been removed?
    a. Make sure the outside strands of wire weren’t stretched, nicked, cut, scraped, or broken during stripping.
  64. What method is used to make shielded wire solder connections?
    a. The pigtail method.
  65. Why must you remove all foreign matter and oxides from metal being soldered?
    a. So the solder will bond to the metal properly.
  66. What can you use to clean component leads prior to soldering them?
    a. A 1/2-inch tinned copper shielding-braid mounted on a spring-type cleaning tool and a white rubber ink eraser.
  67. Can fine sandpaper be used to clean component leads? Explain.
    a. No. The sandpaper could nick or scratch the component lead.
  68. Why shouldn’t freshly soldered leads be moved while they’re cooling?
    a. The joint may fracture, resulting in a cold solder joint that offers high resistance to current and may corrode after a period of time.
  69. How should you connect a heat sink?
    a. Place it between the insulation and the terminal, not touching either one.
  70. What is the purpose of a solder connection?
    a. To aid the connection’s mechanical strength, increase its electrical conductivity, and help prevent corrosion.
  71. How long should the soldering iron be in contact with the connection?
    a. Until the flux is completely boiled out and the connection is thoroughly wetted.
  72. What is wicking?
    a. The process of removing excess solder along the surface of a heated wire.
  73. How should a properly soldered connection look?
    a. It should have a shiny, bright appearance, no pits or holes, and a good concave fillet between wire and terminals.
  74. How is a component lead soldered onto a turret terminal?
    a. To the upper section of the terminal.
  75. What is the minimum and maximum wrap for connecting a conductor to a turret terminal?
    a. 180° minimum, 270° maximum.
  76. When should the solder be applied to a terminal connection?
    a. When the terminal is hot enough to melt the solder readily.
  77. What is the appearance of a properly soldered turret terminal?
    a. The solder should form a concave fillet around the conductor, the outline of the wire should be discernible, and there should be no exposed copper or wire.
  78. List the three ways used to attach conductors to bifurcated terminals?
    a.Top, side, and bottom routes.
  79. You’re inserting a wire into a bifurcated terminal from the top, but the wire doesn’t completely fill the space. What must you do before soldering?
    a. Use a filler wire.
  80. How should insulation lengths compare on multiple wires attached to a bifurcated terminal?
    a. They should be uniform.
  81. What must you do to prepare a solder cup terminal before inserting the wire?
    a. You must heat the solder cup terminal and melt a small amount of solder inside the terminal.
  82. How long should the solder iron contact the solder cup during soldering?
    a. Until all of the flux is boiled out and the solder flows smoothly onto the conductor and terminal surface.
  83. What is the maximum diameter recommended for solder in printed circuit repair?
    a. 1/32 inch.
  84. Why should you ground the soldering iron tip when repairing printed circuit boards?
    a. To keep transistors or small semiconductor devices from being damaged by leakage current from the soldering iron.
  85. What should you do if you have difficulty when soldering a connection?
    a. Stop, let the connection cool completely, and then try again.
  86. Name the two types of lead terminations recommended for printed circuits.
    a. Clinched or unclinched.
  87. How does the use of the second lead termination differ from the use of the first type?
    a. Unclinched terminations are used in special cases where parts are light and no stress is on the solder connection.
  88. How do you vacuum desolder a component from a printed circuit board?
    a. Identify and remove the conformal coating from the solder joint and around the component that’s being desoldered. Place the heated desoldering tip on the joint. When the solder melts, turn on the vacuum pump and draw off the melted solder.
  89. Which method of desoldering would you use to remove a component from a printed circuit board? Explain.
    a. Vacuum desoldering. You can’t wick because the excessive heat and pressure can damage the metal foil or the printed circuit board material.
  90. How should a printed circuit board be mounted to reduce pressure during vacuum desoldering procedures?
    a. In the vertical position.
  91. What are the three basic types for microelectronic circuit packages?
    a. Modules, glass-to-metal packages, and flat packs.
  92. How do you prepare gold-plated leads for soldering?
    a. Remove the gold plating with a white rubber ink eraser, and then tin the leads.
  93. How should copper-clad unplated circuit boards be prepared for soldering?
    a. Clean the pad with a white rubber ink eraser until the pad shows a bright, uniform appearance. Then clean the pad with alcohol and a brush.
  94. In soldering a module to a circuit board, how do you determine where to use clinched or straightthrough termination?
    a. By looking at the TO specifications.
  95. What is the maximum wattage of a soldering iron used to solder modules to a printed circuit board?
    a. 27 watts.
  96. What must you do to flat pack leads before you mount them?
    a. Trimmed and formed.
  97. How do you solder flat packs by the reflow method?
    a. Place the soldering iron to the top center of the lead. When the solder starts to melt, move the soldering iron along the lead in a wiping motion. Add a small amount of solder along the lead to the bend for a proper fillet. When the solder joint is complete, remove the iron using a wiping motion toward the end of the lead.
  98. What would you do before tinning DIPs?
    a. Put a heat sink on the leads.
  99. What should you check while inserting the DIP into the circuit board?
    a. Observe the keying to make sure you’re putting the module in right.
  100. List the five types of printed circuit conductor damage.
    a. Nicks, scratches, breaks, lifting, and terminal area damage.
  101. How should you repair a scratched conductor?
    a. First, remove the conformal coating from an area at least 1/2 inch along the foil on both sides of the scratch; clean the exposed foil with a white rubber ink eraser, followed by brush and alcohol cleaning. Using a smooth dentist-type tool, work (massage) solder into the scratch until the surface is smooth. Add a small amount of flux and then another small amount of solder on top of this. Tin the area using a low-wattage soldering iron. After the connection cools, recoat the exposed area with the appropriate coating.
  102. How should you repair a broken printed circuit conductor?
    a. Clean and prepare the area just as you would for a scratched conductor. Trim out the damaged area at least 0.06 inch from each side so that the angles of the two cut ends of the foil taper toward each other. Lightly tin the cut ends and repair the break with a like piece of foil or jumper wire. Cut the length of replacement foil or jumper wire so that it will extend at least two times the foil width over the sides of the foil being repaired. Remove the adhesive from the area of the replacement foil that will come into contact with the foil being repaired. Tin the contact side of the replacement foil, place it over the break, and lap solder one end to the existing foil. When the connector cools, carefully lift the loose ends of the replacement foil and put a thin film of adhesive on the printed wiring board between the two cut ends. Flatten the replacement foil, then lap solder its other end to the existing foil. After the connection cools, apply pressure with an appropriate C-clamp (Teflon or plastic) and orange sticks. Let the area cure in accordance with the adhesive manufacturer’s instructions, remove excess adhesive with an eraser, then clean and recoat the repaired foil.
  103. After repairing a printed circuit conductor containing a mounting hole, what must you do to the mounting hole?
    a. Clean or drill the mounting hole to restore its original size.
  104. After mounting a replacement terminal area segment, what should you do to be sure the terminal area is securely fastened to the printed wiring board?
    a. Install an eyelet through the terminal hole.
  105. Use the conversion formula to convert 15° C to Fahrenheit.
    a. 59° F
  106. Use the conversion formula to convert 95° F to Centigrade.
    a. 35° C
  107. In terms of resistance and thermal expansion, what happens to pure metal when heat is applied?
    a. Resistance increases and the metal and metal alloys expand.
  108. Give two examples mentioned in the text of practical uses of the principle of thermal expansion.
    • a. (1)Bimetallic strip, (2)Pneumatic thermostat.
    • Name two people who discovered laws concerning the relationships among pressure, temperature, and volume of a confined gas.
    • a. Boyle and Charles.
  109. How does increasing the pressure of a confined gas affect its volume when temperature is constant?
    a. Volume decreases.
  110. When temperature decreases, how does a decrease in pressure of a confined gas affect its volume?
    a. Volume decreases.
  111. Name two types of magnets.
    a. Natural and artificial magnets
  112. Name two types of artificial magnets.
    a. Permanent and temporary.
  113. What is reluctance?
    a. The opposition a material offers to the magnetic lines of force
  114. What is residual magnetism?
    a. The amount of magnetism that remains in a temporary magnet.
  115. What is retentivity?
    a. The ability of a material to retain residual magnetism.
  116. What is permeability?
    a. The ease with which magnetic lines of force distribute themselves throughout the material.
  117. In what regions of a magnet are the lines of force concentrated?
    a. The magnetic poles.
  118. If a piece of wire with electron flow is formed into a loop, what type of magnet does it act like?
    a. A bar magnet.
  119. How can sensitive instruments be protected from stray magnetic fields?
    a. Encase them in a highly permeable shielding (like soft iron).
  120. What is an electromagnet?
    a. An electrically excited magnet that can exert mechanical force.
  121. If you put a piece of iron through a wire coil, what type of magnet do you get?
    a. An electromagnet.
  122. What does saturated mean in reference to electromagnets?
    a. If you continually increase the current in a coil with an iron core, you eventually reach a point where further current increases add so few flux lines that it’s uneconomical and impractical to add more lines.
  123. Name two things that will damage a magnet and make it lose its magnetism.
    a. Improper handling such as severe jarring or heating it.
  124. Very briefly describe the three particles that make up an atom.
    a. Neutrons are neutral (no charge) particles, protons are positively charged particles in the nucleus, and electrons are the negatively charged particles in orbit around the nucleus.
  125. What electrical charge does an atom have under normal conditions?
    a. A neutral charge, because the electrons balance the protons.
  126. Name three forces that cause electrons to be released from their orbit.
    a. Any three of the following: heat, light, pressure, checmicals, and changing magnetic field.
  127. Name three materials that make good insulators and state why they do.
    a. Wood, plastic, rubber, and glass; they hold their orbiting electrons tightly in place by the nucleus.
  128. What’s the electrical term for material with loosely bound electrons?
    a. Conductor.
  129. What is electrical pressure, and what is its unit of measurement?
    a. Electromotive force and it’s measured in volts.
  130. What factors determine a material’s resistance?
    a. Type, size, and temperature of material.
  131. What is the unit of measurement for resistance?
    a. Ohms.
  132. If a circuit contains 5 ohms of resistance and 50 volts are applied, what will the current flow be?
    a. 10 amperes.
  133. What is the voltage of a circuit that has 3 amperes of current flow and 4 ohms of resistance?
    a. 12 volts.
  134. What is the power of a circuit that has 2 amperes of current flow and 5 ohms of resistance?
    a. 20 watts.
  135. What type of circuit has more than one path for current flow?
    a. Parallel.
  136. What stays the same in all legs of a parallel circuit?
    a. Voltage applied.
  137. If voltage is constant, what happens to total circuit resistance if you add resistors to a parallel circuit?
    a. Total circuit resistance would decrease.
  138. What is the total amperage of a parallel circuit with a 12-volt power source and three resistors with values of 12, 4, and 6 ohms?
    a. 6 amps.
  139. In the simplest terms, what is a series-parallel circuit?
    a. It’s a circuit that has parallel resistances connected in series with other resistances.
  140. Find the total resistance of a series-parallel circuit with 2 parallel, 20 resistors in series with a 30 resistor.
    a. 40 ohms.
  141. What rule is used to determine the direction of movement of a conductor in a magnetic field?
    a. The right-hand motor rule.
  142. What principles govern the movement of the coil (armature) in a DC motor?
    a. Laws of magnetism.
  143. What units reverse the direction of current flow to the coil (armature) of a DC motor?
    a. The commutator and brushes.
  144. What is effective electromotive force?
    a. Applied voltage minus the induced voltage, which is also referred as counter-electromotive force (CEMF).
  145. What keeps a DC motor’s current from rising high enough to destroy the coil?
    a. CEMF.
  146. Name two ways of varying the strength of CEMF.
    a. Increase motor speed or field strength.
  147. When a sine wave starts at zero and increases to its maximum positive or negative voltage, what is this voltage called?
    a. Peak voltage.
  148. What’s the unit of measurement for frequency?
    a. Hertz.
  149. Name the components of a basic AC generator.
    a. Armature, permanent magnet, slip rings, and brushes.
  150. What is inductance, and what is its symbol?
    a. Inductance is a property of a circuit that opposes any change in current flow. Its symbol is L.
  151. What’s the unit of measure for inductance, and what’s its symbol?
    a. Hertz.
  152. In what type of AC circuit will voltage lead current by 90°?
    a. Armature, permanent magnet, slip rings, and brushes.
  153. What factors determine a coil’s inductance?
    a. The number of turns in the coil, the diameter of the coil, the coil length, and the type of material used for the core.
  154. What is impedance, and what term expresses its value?
    a. The total opposition to current flow in an AC circuit; it’s expressed in ohms.
  155. What is the symbol for capacitance?
    a. C.
  156. What’s the unit of measurement for capacitance, and what symbol do you use?
    a. The farad, but since that’s usually too large a unit, you usually use microfarads (μF or MFD).
  157. If voltage is at maximum in a purely capacitive circuit, what’s the current value?
    a. Zero.
  158. What is the phase relationship of voltage and current in a capacitive circuit?
    a. Current leads voltage by 90°.
  159. What factors determine the amount of charge (effectiveness) of a capacitor?
    a. Size of the plates, spacing between the plates, and the dielectric.
  160. Name the two classes of capacitors.
    a. Fixed and variable.
  161. Paper capacitors are seldom used where the voltage exceeds what value?
    a. 600 volts.
  162. Which transformer windings connect to the source voltage?
    a. The primary.
  163. Which transformer windings connect to the load side?
    a. The secondary.
  164. What type of core material is required for transformers in low-frequency circuits?
    a. A core of low-reluctance magnetic material.
  165. What do you call the transformer in question 3?
    a. An iron-core transformer.
  166. What is the turns-ratio?
    a. The ratio of the number of turns in the primary to the number of turns in the secondary.
  167. How do you refer to a transformer if, when you apply 10 volts to the primary, the voltage across its secondary reads 2 volts?
    a. As one with a 5-to-1, step-down, turns-ratio.
  168. What does “coefficient of coupling” refer to?
    a. The extent to which magnetic lines of the primary cut across the secondary.
  169. What does a .9 coefficient of coupling mean?
    a. 90 percent of the primary winding’s lines of flux are cutting the secondary winding.
  170. What AC-induction motor components compare to the DC motor’s field and armature windings?
    a. The AC rotor compares to a DC motor’s armature; the AC stator compares to a DC field winding.
  171. What two types of rotors are commonly used in AC induction motors?
    a. Squirrel cage and wound.
  172. What turns the rotor of an induction motor?
    a. The rotating magnetic field causes rotor torque and rotation.
  173. What is slip?
    a. Slip is the difference between the speed of the stator field and the rotor.
  174. Name the parts of a transistor and state what each does.
    a. The emitter emits current carriers (electrons or holes), the base controls their flow, and the collector collects them.
  175. Name the classes of transistors.
    a. NPN and PNP.
  176. How is each class formed?
    a. An NPN transistor is formed by introducing a thin region of P-type material between two regions of N-type material in a single crystal of germanium or silicon. A PNP transistor is formed by introducing a thin region of N-type material between two regions of P-type material.
  177. How are the two junctions of a transistor biased in normal operation?
    a. The emitter-base junction is forward biased and the collector-base junction is reverse biased.
  178. What happens to some of the electrons that move into the base region in an NPN transistor under normal operation?
    a. Some of the electrons recombine with holes and move out through the base lead in the form of base current (IB) and return to the emitter supply battery VEE.
  179. What’s the current path in an NPN transistor under correct bias?
    a. In an NPN, the current path is from the negative terminal of the emitter supply battery to the emitter. It flows through the emitter to the base. From the base, a small part returns to the positive terminal of the emitter battery. The rest flows from the base through the collector to the positive terminal of the collector battery as collector current (IC).
  180. How does current flow in the external circuit of a PNP transistor compare to current flow in an NPN transistor?
    a. It is opposite.
  181. Which way does the arrow point in a PNP transistor symbol?
    a. In a PNP transistor, the arrow points toward the base lead.
  182. Which way does it point in an NPN symbol?
    a. In an NPN transistor, the arrow points toward the emitter lead.
  183. What is the direction of external current flow in a transistor?
    a. External current flow is always against the arrow.
  184. What are the three basic transistor configurations?
    a. Common emitter, common base, and common collector.
  185. What’s the phase of a common emitter’s input compared to its output phase?
    a. The input is 180° out of phase with the output of a common emitter.
  186. What’s the current gain of a common-emitter transistor circuit?
    a. The current gain of a common emitter is high.
  187. What’s the common emitter’s response to high frequencies?
    a. It has a comparatively low response to high frequencies.
  188. Which way does current flow in the PNP common-base transistor?
    a. Current flows into the collector and base leads and out of the emitter lead.
  189. What else do you call the common-collector configuration?
    a. An emitter follower.
  190. What is the input and output impedance of a common collector transistor configuration?
    a. There’s a high input impedance and a low output impedance.
  191. What is the signal voltage phase reversal between input and output of a common collector?
    a. There’s no phase reversal in a common collector between input and output.
  192. What are the essential items for a DC-power supply to operate?
    a. An AC source and a rectifier.
  193. What is the simplest type of rectifier?
    a. The single-phase half-wave rectifier.
  194. In a half-wave rectifier, what does grounding either end of the output DC supply for an isolation transformer determine?
    a. Whether the DC output is positive or negative.
  195. What is used to produce a steady DC output of a half-wave rectifier?
    a. Filters.
  196. How many diodes must a full-wave rectifier have?
    a. At least two.
  197. What is an important factor in designing a full-wave rectifier circuit for peak-voltage output?
    a. The semiconductor diode’s peak-inverse-voltage rating.
  198. Explain logic gates.
    a. Electronic circuits designed to have a certain output when specific conditions are met.
  199. What is a NAND logic gate?
    a. An AND gate with an inverter or a NOT gate at the output that changes a low output to a high output and vice versa.
  200. What establishes the high output in the NOR-gate circuit?
    a. Saturation conduction of Q1.
  201. In troubleshooting a resistive parallel DC circuit, you find the current has decreased. What would be a probable cause?
    a. A resistor in one of the branches has become open. Total circuit resistance has increased causing the drop in current.
  202. In troubleshooting that same circuit, what reading will you get when you place an ammeter in the branch with the open resistor?
    a. Zero.
  203. Why must you disconnect a defective component from its circuit when you check it with an ohmmeter?
    a. To keep shunt or parallel loads from affecting the resistance reading.
  204. In a parallel circuit with three branch resistors, how does shorting one resistor affect circuit operation?
    a. Total circuit current would increase greatly.
  205. How does an open in the series part of a series-parallel circuit affect current flow?
    a. Stops current flow.
  206. How does a short in the series part of a series-parallel circuit affect current flow?
    a. Current will increase.
  207. If there’s a short in the parallel part of a series-parallel circuit, what will the reading be?
    a. Total resistance of the circuit is decreased.
  208. What will a voltmeter read across a good series resistor in a series-parallel circuit?
    a. It will read part of the applied voltage (the voltage dropped by the series resistor).
  209. What must you do before connecting an ohmmeter into an electrical circuit?
    a. Disconnect the power source from the circuit.
  210. What is the meter reading on an ohmmeter connected across a shorted component?
    a. Lower than normal or zero will be indicated.
  211. Explain how a voltmeter is connected in a circuit.
    a. Between the two points to be checked (in parallel).
  212. List two precautions to observe when using a voltmeter.
    a. Set the voltmeter range higher than the voltage being tested and connect to the proper polarity.
  213. What actions should be taken prior to connecting an ohmmeter into a circuit?
    a. Disconnect all sources of circuit power, remove each unit and individually check each one.
  214. Define infinity.
    a. Immeasurable resistance or open circuit.
  215. Define continuity.
    a. No resistance or a complete circuit.
  216. How is an ammeter connected in a series circuit?
    a. In series with the circuit.
  217. What will happen if you connect an ammeter in Parallel with a circuit?
    a. The meter will give a false indication by measuring only the part of the current that’s actually flowing through the meter.
  218. List the electrical characteristics that can be measured using a multimeter.
    a. AC volts, DC volts, current, resistance and frequency in some meters.
  219. What is the purpose of the LEAd symbol on the meter display?
    a. It is a reminder to verify that the Red meter lead is in the correct jack.
  220. Explain the HOLD function on the fluke multimeter.
    a. Gives you the ability to take measurements that are difficult or hazardous to reach without taking your eyes off the test leads.
  221. What is the purpose of the YELLOW button?
    a. To select alternate functions on a rotary switch setting.
  222. When testing diodes, how will you know if you have a bad diode?
    a. The meter will either show OL in both positions if the Diode is open or it will beep continuously if shorted.
  223. What are the four range settings that you can select on the fluke multimeter and what do they represent?
    a. 6, 60, 600, 1000; the maximum value of volts or current that you can measure in that selected range.
  224. What is the purpose of a frequency meter?
    a. To check and adjust the frequency of the voltage source.
  225. To read frequency, how are the meters attached to the circuit?
    a. Frequency meters are connected in the same manner voltmeters are.
  226. Describe storing precautions that should be observed when storing meters and test equipment.
    a. Don’t let the meter leads hang out when they’re not in use, and make sure you don’t crush or pinch them when you put the cover in place. Store the meter in the shop where it won’t be subjected to extreme or varying temperatures, dampness, or jarring.
  227. What types of overheat detectors can the X–1A test and adjust?
    a. Types E–2 and E–4 and other types of thermal switches in aircraft overheat systems.
  228. What does the POWER ON-OFF switch do?
    a. It controls power to the heat block.
  229. When should you use the HIGH position on the X–1A?
    a. Use the HIGH position for initial heating.
  230. What should you do to energize the antiskid system?
    a. Use the aircraft maintenance instructions to turn on the required aircraft power.
  231. What should you use to set up the tester controls?
    a. The information on the tester panel.
  232. What is the primary purpose of the A510A load bank?
    a. It simulates aircraft operation as a convenient mobile means for load-testing aircraft-type, four-wire, AC generators with 120/208 volt, three-phase, 400-Hz rating.
  233. What should you check to measure the phase shift between the line voltage and line current?
    a. The power factor meter circuit.
  234. In what position do you set the range selector switch during preliminary adjustment?
    a. 250-AMP position.
  235. List things that can degrade a wire’s ability to carry an undistorted signal.
    a. Crushing, crimping and fraying of the wire.
  236. What maximum length of cable can the ESP check?
    a. 1000 feet.
  237. How does the ESP measure the distance between the ESP and a defect in the wire?
    a. By the amount of time it took for the pulse to return to the ESP.
  238. What is an Igniter Circuit tester?
    a. It is a precision instrument designed to test explosives and other volatile devices.
  239. What indicates that the Failsafe ohmmeter battery is low and needs to be recharged?
    a. The LED display shows a negative (-) or minus sign in the indicator box.
  240. What is indicated when the Failsafe ohmmeter display flashes “0000”?
    a. The ohmmeter is reading an “open circuit” condition or a resistance value higher than the current selected range button.
  241. If the OHMS dial setting is 2 and the OHMS ADD dial setting is 20, what is your circuit resistance?
    a. 22 ohms.
  242. What does the K400B generator test stand consist of?
    a. The K400B test stand consists of an operator’s control console, a drive stand with speed increaser gearbox and stand mounted hydraulic oil supply, drive stand power unit, a resistive and reactive load bank, and an isolation transformer.
  243. What is the oscilloscope on the control panel used for?
    a. To monitor and evaluate waveforms and transient signals.
  244. Explain the purpose of the drive stand control unit.
    a. It is a microprocessor assembly that provides the test data to the console and controls the drive stand and hydraulics subsystem.
  245. What happens if cooling air is lost within the load bank?
    a. An airflow switch in the load bank will disconnect the load.
  246. What does a typical drive start sequence include?
    a. The desired rotation of the drive, overspeed rpm value, unit under test protections, the speed or rpms, and the ramp rate.
  247. It the lamp in the top section of figure 4–14 is open, what does the voltmeter across it read?
    a. 24 VDC.
  248. What does a voltmeter connected across the battery read if the lamp in top section of figure 4–14 is open?
    a. The voltmeter completes the circuit so that it reads 24 VDC.
  249. Referring to figure 4–16, what does an ohmmeter indicate when connected across the isolated lamp in the circuit with the shorted resistor?
    a. The resistance of the lamp (or 6 ohms).
  250. In figure 4–16, if the lamp is shorted, what resistance reading is shown with the ohmmeter connected across the lamp?
    a. 0 ohms.
  251. What does a blown fuse normally indicate?
    a. The current flow exceeds a maximum amount.
  252. Checking a disconnected wire in a grounded circuit, the ohmmeter reads infinity to ground. What does this indicate?
    a. Normal reading because the wire is disconnected from the circuit.
  253. What important task should the supervisor perform when anyone is assigned to battery shop work?
    a. Ensure that battery shop personnel are thoroughly trained and indoctrinated in safe operating procedure.
  254. What must you use when wearing glasses in the battery shop and why?
    a. A lanyard must be worn; to prevent the glasses from falling off the face.
  255. Name three items that must be provided for the workers’ protection when working in the battery shop.
    a. Full face shields, rubber gloves, and rubber aprons.
  256. What should you do if you find a SLAB cracked or leaking?
    a. Terminate any maintenance, turn off all equipment, and don face shield, rubber apron, and rubber gloves.
  257. Why should a deluge shower and eye wash be installed in a battery shop?
    a. To be used in case electrolyte is accidentally splashed or spilled on you. The faster you get under the shower and wash away or neutralize the electrolyte, the less you’ll be burned.
  258. What gas is produced when charging batteries? What hazards does it create?
    a. Hydrogen gas. It is a colorless, odorless, highly flammable gas you won’t know is there until it’s too late; it is also highly flammable and can explode.
  259. What can you use to neutralize Ni-Cad electrolyte on your skin?
    a. Vinegar, citrus (such as lemons or limes), or a 5 percent boric acid solution.
  260. What kind of protective clothing should you wear when servicing Ni-Cad batteries?
    a. An alkali-proof rubber apron, rubber gloves, and face mask.
  261. Why is smoking prohibited in the battery shop?
    a. Because hydrogen gas is very explosive.
  262. What does a lead-acid battery’s electrolyte consist of?
    a. Sulfuric acid and water.
  263. How are spilling and leaking prevented in aircraft batteries?
    a. By using a specially designed pressure valve that is permanently installed in each cell.
  264. What are the thin porous sheets of insulating material in the battery called and what are they used for?
    a. They are called separators and are used to electrically insulate the plates from each other.
  265. What is the battery capacity’s measured in (unit of measurement)?
    a. Ampere hours (Ah).
  266. What do the plates of a nickel-cadmium battery consist of?
    a. Nickel oxide on the positive plate and metallic cadmium on the negative.
  267. What is the open-circuit voltage of a Ni-Cad cell?
    a. 1.25 volts.
  268. From what are the separators in the Ni-Cad made?
    a. Either the combination of nylon and cellophane or of a material called permion.
  269. At what point does the vent cap release gas pressure?
    a. When gas pressure reaches between 2 to 10 psi.
  270. What is the electrolyte mixture made up of in a Ni-Cad?
    a. 30 percent solution of potassium hydroxide (KOH) in distilled water.
  271. What is thermal runaway?
    a. An uncontrollable rise in battery temperature that can destroy the battery.
  272. What is used to check the electrolyte level in a Ni-Cad battery cell?
    a. A clear plastic or glass tube.
  273. What do you use to adjust electrolyte in a Ni-Cad battery cell?
    a. A polyethylene wash bottle with a tube attached.
  274. What is the thermometer used for?
    a. To monitor battery temperature.
  275. What is the purpose of the metering display on the RF80-K Charger/Analyzer?
    a. It displays battery voltage, cell voltage, or charge/ discharge current.
  276. How long must the AFTO Form 161 be kept with the SLAB and how long must it be maintained?
    a. The form must stay with the battery until the battery is issued to the flightline at which time the form is required to be filed and maintained for at least 1 year but preferably throughout the battery’s service life.
  277. What is the Combination Maintenance charge?
    a. It is a two step charge used on batteries with an open circuit voltage between 20.5 - 24.9 volts. This is the preferred method to charge all batteries that pass their discharge capacity test.
  278. Why must a SLAB’s voltage not be allowed to rise above 31.5 VDC?
    a. Venting will occur and valuable electrolyte will be permanently lost.
  279. What is the purpose of discharge capacity testing a lead-acid battery?
    a. To verify the SLAB is capable of being discharged to its ampere hours capacity rating.
  280. What happens to a lead-acid battery that fails the capacity test?
    a. The battery will be recharged using the Combined Maintenance charge; it can fail 3 times before being condemned.
  281. After they are cleaned and inspected, what check must be performed on all nickel-cadmium batteries that are brought into the shop?
    a. A capacity check.
  282. At what voltage is the shorting device placed on the Ni-Cad battery?
    a. .5 volts.
  283. How many chances must you give a cell to pass the capacity test before the cell is condemned?
    a. Three.
  284. When are the cells of a Ni-Cad battery considered equalized?
    a. When the cell voltage of each cell is zeroized, dropping below .5 volt.
  285. By what method is the nickel-cadmium battery charged?
    a. Reflex charge or constant-current method.
  286. When adjusting the electrolyte level in a Ni-Cad battery, how far above the plates should the level be?
    a. 1/8 inch.
  287. When would galvanic corrosion occur?
    a. When dissimilar metals come in contact with each other and moisture is present to form an external circuit.
  288. How would you describe pitting corrosion?
    a. It is first noticeable as a powdery deposit that when cleaned away, leaves pits on the surface.
  289. Where does intergranular corrosion take place?
    a. At the grain boundaries of a metal alloy.
  290. What type of corrosion is caused by the simultaneous effects of tensile stress and corrosion?
    a. Stress corrosion cracking.
  291. What preventive measure would provide early corrosion detection?
    a. Inspection.
  292. Cite three areas that are prone to corrosion.
    a. Any three of the following: (1)Overlapping joints, (2)Areas around fasteners (bolts, rivets), hinges, and antennas, (3)Drain holes that may be plugged, (4)Fittings and plumbing, (5)Structure under floorboards, (6)Areas where moisture may accumulate, (7)Areas where dissimilar materials are in contact, (8)Wheel wells and exposed areas, (9)Air intakes and exhausts, (10)Fire extinguishing systems and components.
  293. Why must you rinse a component after cleaning it with an oily based cleaning solvent?
    a. To prevent an accumulation of dust or dirt.
  294. How should you treat a small surface that has paint chipping off?
    a. Spot painting.
Card Set
2A656 VOL 2 Q&A
2A656 VOL 2 Q&A