What type of screwdriver fits cross-recessed screws?
a. A cross-point screwdriver.
What type of screwdriver should you use if there's not enough room for a standard screwdriver?
a. An offset screwdriver.
How do you know whether you're using the right size screwdriver?
a. The blade will fit the screw slot snugly.
What type of hammer is most widely used by mechanics?
a. Ball-peen hammer.
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
Why should you pull a wrench, rather than pushing it?
a. To keep from injuring your hand.
Which wrench is good for loosening and tightening odd-size nuts and bolts?
a. An adjustable-jaw wrench.
Should you use a speed handle on the socket wrench to break nuts loose?
a. No, use a hinge handle.
What type of file should you use on hard steel?
a. Start with a smooth file and finish with a dead-smooth file.
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.
Why do you use thickness gauges?
a. To measure clearance between two objects.
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.
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).
How do you reduce the setting on a torque wrench?
a. Turn the handle counterclockwise.
How often must a torque wrench be verified?
a. Every 60 calendar days.
In preparing a torque wrench for storage, what do you set the scale on?
a. The lowest usable setting.
How do you identify a section of tubing in the oxygen system?
a. With green coding tape labeled "breathing oxygen".
What kind of fitting do you use to route tubing through a bulkhead?
a. Bulkhead fitting.
How are special bolts usually identified?
a. By the letter S on the bolt head.
What should you consider in selecting the shank and grip length of a bolt?
a. Check for proper diameter, length, and good mechanical fit.
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.
What safetying device is used with a castle nut?
a. Cotter pin.
When can you use single-strand safety wiring?
a. When the bolts or screws are closely grouped.
How do you secure an AN connector plug?
a. Safety wire it at installation with at least 0.020-inch wire.
How do you safety a V-band clamp?
a. Run a double strand through the clamp, and twist the ends together.
Why does aircraft wiring have many small strands of wire instead of a solid core?
a. To make the wire more flexible.
What methods are authorized marking wires and cables?
a. Direct marking and Indirect marking.
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.
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.
What's the maximum distance between ties on a wire bundle?
a. Twelve inches.
What is the advantage of flat tape over round cord?
a. Tape won't cut into wire bundles.
What are the two types of terminals?
a. Soldered and solderless.
Why shouldn't terminal eyelets be enlarged?
a. It reduces the amount of material and thus its current-carrying capabilities.
How are terminal lugs secured to terminal studs?
a. So that any movement of the lug will cause tightening.
What method of splicing is most widely used?
a. Crimp-on method.
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.
Which component of the connector is the fixed part?
a. The receptacle.
What ensures proper mating of the connector plug and receptacle?
a. A key and keyway arrangement in the barrel.
What information gives the class, size and type of connector?
a. The part number stamped on the barrel.
How much will thermofit shrink when heated with the heat-shrinking tool?
a. At least half of its original diameter.
What type of material is used in fabricating boots, end caps, sleeving, and tubing?
a. Thermofit material.
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.
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.
What is the maximum ohm value for a bonding or grounding jumper connection?
a. No more than 0.1 ohm.
What is the purpose of shielded wire?
a. To provide a barrier to electrostatic interference with instruments, radios, etc.
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.
What type of solder is preferred when temperature limitations are critical?
a. 63/37 solder.
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.
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.
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.
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.
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.
Why should copper tips be filed cold?
a. A tip that's filed hot will oxidize quickly and cause tinning to be difficult.
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.
How can thermal strippers prevent blistering or excessive melting of insulation?
a. By having a controlled-heat output.
When can you use needle-nose pliers as a bending tool?
a. When the jaw tips are covered with copper tubing.
What can you use to clean gold plating from printed circuit pads?
a. A white rubber ink eraser.
What keeps you from being tempted to grab a falling work piece?
a. Work pieces are securely supported before you start.
What should you do to keep from being struck in the eye by pieces cut from wire strands?
a. Wearing of proper eye protection.
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.
State five safeguards against being burned by a hot soldering iron.
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.
How is the insulation clearance of a wire determined?
a. By the diameter of the wire (including insulation).
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.
What method is used to make shielded wire solder connections?
a. The pigtail method.
Why must you remove all foreign matter and oxides from metal being soldered?
a. So the solder will bond to the metal properly.
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.
Can fine sandpaper be used to clean component leads? Explain.
a. No. The sandpaper could nick or scratch the component lead.
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.
How should you connect a heat sink?
a. Place it between the insulation and the terminal, not touching either one.
What is the purpose of a solder connection?
a. To aid the connection's mechanical strength, increase its electrical conductivity, and help prevent corrosion.
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.
What is wicking?
a. The process of removing excess solder along the surface of a heated wire.
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.
How is a component lead soldered onto a turret terminal?
a. To the upper section of the terminal.
What is the minimum and maximum wrap for connecting a conductor to a turret terminal?
a. 180° minimum, 270° maximum.
When should the solder be applied to a terminal connection?
a. When the terminal is hot enough to melt the solder readily.
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.
List the three ways used to attach conductors to bifurcated terminals?
a.Top, side, and bottom routes.
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.
How should insulation lengths compare on multiple wires attached to a bifurcated terminal?
a. They should be uniform.
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.
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.
What is the maximum diameter recommended for solder in printed circuit repair?
a. 1/32 inch.
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.
What should you do if you have difficulty when soldering a connection?
a. Stop, let the connection cool completely, and then try again.
Name the two types of lead terminations recommended for printed circuits.
a. Clinched or unclinched.
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.
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.
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.
How should a printed circuit board be mounted to reduce pressure during vacuum desoldering procedures?
a. In the vertical position.
What are the three basic types for microelectronic circuit packages?
a. Modules, glass-to-metal packages, and flat packs.
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.
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.
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.
What is the maximum wattage of a soldering iron used to solder modules to a printed circuit board?
a. 27 watts.
What must you do to flat pack leads before you mount them?
a. Trimmed and formed.
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.
What would you do before tinning DIPs?
a. Put a heat sink on the leads.
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.
List the five types of printed circuit conductor damage.
a. Nicks, scratches, breaks, lifting, and terminal area damage.
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.
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.
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.
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.
Use the conversion formula to convert 15° C to Fahrenheit.
a. 59° F
Use the conversion formula to convert 95° F to Centigrade.
a. 35° C
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.
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.
How does increasing the pressure of a confined gas affect its volume when temperature is constant?
a. Volume decreases.
When temperature decreases, how does a decrease in pressure of a confined gas affect its volume?
a. Volume decreases.
Name two types of magnets.
a. Natural and artificial magnets
Name two types of artificial magnets.
a. Permanent and temporary.
What is reluctance?
a. The opposition a material offers to the magnetic lines of force
What is residual magnetism?
a. The amount of magnetism that remains in a temporary magnet.
What is retentivity?
a. The ability of a material to retain residual magnetism.
What is permeability?
a. The ease with which magnetic lines of force distribute themselves throughout the material.