Fasteners Identification and Types
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Questions and Answers

Which of the following standards identifies threaded fasteners and rivets?

  • ISO
  • AN (correct)
  • ASTM
  • IEEE

    • What is typically indicated by a Class 4 fit for aircraft fasteners?

  • No defined grip length
  • Very loose fit
  • Easy to turn with fingers
  • Use of a wrench required (correct)

    • What distinguishes a bolt from a screw in terms of threaded section?

  • Screws do not have threaded sections.
  • Bolts have longer threaded sections.
  • Bolts have shorter threaded sections. (correct)
  • Both have the same size threaded sections.

    • Which fastening method provides quicker dismantling for aircraft parts?

    <p>Bolting</p> Signup and view all the answers

    What is the primary concern when selecting substitutes for aircraft fasteners?

    <p>Strength and compatibility with original fastener</p> Signup and view all the answers

    Which of the following is NOT a head style for AN bolts?

    <p>Countersunk</p> Signup and view all the answers

    What class fit are aircraft screws generally manufactured with?

    <p>Class 2</p> Signup and view all the answers

    What does the letter 'S' stamped on the head of a bolt typically indicate?

    <p>Special bolt</p> Signup and view all the answers

    What distinguishes AN-type aircraft bolts from other bolts?

    <p>Code markings on the bolt heads</p> Signup and view all the answers

    Which marking indicates corrosion-resistant steel for AN standard bolts?

    <p>A single raised dash</p> Signup and view all the answers

    What feature distinguishes self-locking nuts from non-self-locking nuts?

    <p>They do not require external locking devices</p> Signup and view all the answers

    What type of nut is specifically designed to accommodate a cotter pin or lockwire?

    <p>Castle nut</p> Signup and view all the answers

    How can NAS bolts be identified differently from AN bolts?

    <p>By raised or recessed markings</p> Signup and view all the answers

    Which bolt is typically used in applications subjected only to shearing stress?

    <p>Castellated shear nut</p> Signup and view all the answers

    What is a primary characteristic that limits the use of the plain hex nut on aircraft structures?

    <p>It requires an auxiliary locking device</p> Signup and view all the answers

    What type of bolt marking indicates a standard AN-type bolt?

    <p>Raised X or asterisk</p> Signup and view all the answers

    What type of nut must always be secured with an external locking device?

    <p>Non-self-locking nut</p> Signup and view all the answers

    What is the function of color lacquer or distinctive markings on bolts inspected magnetically?

    <p>Determine if they have been inspected</p> Signup and view all the answers

    What is the primary purpose of the wing nut, AN350?

    <p>To allow for easy removal and finger-tightening</p> Signup and view all the answers

    Under what conditions should self-locking nuts not be used?

    <p>Where either the nut or bolt will rotate</p> Signup and view all the answers

    How does the locking mechanism of the Boots self-locking nut function?

    <p>It incorporates a spring that maintains tension between sections</p> Signup and view all the answers

    What are the characteristics of the stainless steel self-locking nut?

    <p>Its locking action occurs as it is tightened against a surface</p> Signup and view all the answers

    What feature is unique to the Elastic stop nut?

    <p>It has a nylon locking collar that increases resistance</p> Signup and view all the answers

    What should be checked before reusing an elastic stop nut?

    <p>The condition of the nylon locking collar</p> Signup and view all the answers

    Which material is the Rol-top nut made from?

    <p>Cadmium-plated steel</p> Signup and view all the answers

    What is the primary function of the nylon collar in the Elastic stop nut?

    <p>To create friction that enhances locking capability</p> Signup and view all the answers

    What is necessary for the effective use of self-locking nuts on certificated aircraft?

    <p>Compliance with manufacturer restrictions</p> Signup and view all the answers

    What characteristic differentiates the Boots self-locking nut from standard nuts?

    <p>Construction that includes a spring and dual sections</p> Signup and view all the answers

    How is corrosion-resistant steel indicated on AN standard bolts?

    <p>By a single raised dash</p> Signup and view all the answers

    What is the significant difference between the Castle nut and the Castellated shear nut?

    <p>The Castle nut is deeper and can withstand larger tensile loads.</p> Signup and view all the answers

    Which characteristic distinctly identifies the AN aluminum alloy bolts?

    <p>Marked with two raised dashes</p> Signup and view all the answers

    What type of nuts must be secured by external locking devices?

    <p>Non-self-locking nuts</p> Signup and view all the answers

    What marking is used for close tolerance NAS bolts?

    <p>Raised triangle</p> Signup and view all the answers

    Which of the following is NOT a type associated with non-self-locking nuts?

    <p>Light hex nut</p> Signup and view all the answers

    What feature must an auxiliary locking device provide when used with the plain hex nut?

    <p>It must secure the nut against loosening.</p> Signup and view all the answers

    How can bolts inspected by magnetic or fluorescent methods be identified?

    <p>By their color or head marking of a distinctive type</p> Signup and view all the answers

    Which type of nut is primarily used for miscellaneous light tension requirements?

    <p>Light hex nut</p> Signup and view all the answers

    What must be evident in the construction of self-locking nuts?

    <p>They contain an integral locking feature.</p> Signup and view all the answers

    What is the primary reason bolting is preferred over riveting for some aircraft joints?

    <p>Bolts allow for easy replacement without weakening the joint.</p> Signup and view all the answers

    What type of fit do aircraft bolts typically use?

    <p>Class 3 fit for general applications.</p> Signup and view all the answers

    Which statement best describes the assembly process of a bolt compared to a screw?

    <p>A bolt is typically tightened by turning the nut while a screw is tightened by turning its head.</p> Signup and view all the answers

    What precaution should be taken if duplicate aircraft fasteners are unavailable?

    <p>Carefully consider specifications before selection.</p> Signup and view all the answers

    Which distinguishing feature identifies special bolts in aviation?

    <p>The letter 'S' stamped on the head.</p> Signup and view all the answers

    How are aircraft screws typically manufactured in terms of fit?

    <p>Class 2 fit for ease of assembly.</p> Signup and view all the answers

    What is the main purpose of the grip length on bolts compared to screws?

    <p>To affect the overall strength of the joint.</p> Signup and view all the answers

    Which head style is NOT associated with AN-type bolts?

    <p>Internal wrenching head.</p> Signup and view all the answers

    Which class fit allows bolts to be turned easily by fingers?

    <p>Class 1 fit.</p> Signup and view all the answers

    What distinguishes a bolt's threaded section length in applications?

    <p>It is critical for ensuring proper engagement.</p> Signup and view all the answers

    What is a specific limitation of using self-locking nuts in applications involving rotation?

    <p>They may result in damage to the bolt threads.</p> Signup and view all the answers

    Which feature of the Boots self-locking nut enhances its performance under severe vibration?

    <p>The dual nut design with a locking spring.</p> Signup and view all the answers

    How does the nylon collar in the Elastic stop nut contribute to its locking mechanism?

    <p>By creating downward pressure when a bolt is inserted.</p> Signup and view all the answers

    What is the mechanism by which the locking action of the stainless steel self-locking nut occurs?

    <p>Compression of the threaded insert against the bolt.</p> Signup and view all the answers

    What material finish is typically associated with the Rol-top nut?

    <p>Cadmium plating.</p> Signup and view all the answers

    What is a common characteristic of the elastic stop nut that enhances its reusable nature?

    <p>The durability of the nylon locking collar.</p> Signup and view all the answers

    Why is it necessary to ensure that the fibre of the elastic stop nut has not lost its locking friction?

    <p>To maintain a secure fit during reuse.</p> Signup and view all the answers

    What unique property does the nylon collar in an elastic stop nut possess regarding environmental exposure?

    <p>It remains unaffected by common solvents and temperatures.</p> Signup and view all the answers

    What essential feature must be present for effective use of self-locking nuts on certificated aircraft?

    <p>Specific structural support provided by manufacturers.</p> Signup and view all the answers

    What distinguishes the Elastic stop nut from the other types of self-locking nuts mentioned?

    <p>It includes a nylon locking collar for enhanced security.</p> Signup and view all the answers

    Study Notes

    Fasteners: Identification and Types

    • Fasteners (threaded and rivets) are identified by AN (Air Force-Navy), NAS (National Aircraft Standard), or MS (Military Standard) numbers.
    • Fastening processes must create a joint as strong as the joined parts.
    • Alternative fasteners (bolts, screws) allow for easier disassembly and reassembly of aircraft parts without weakening joints. Riveting or welding these parts each time they are serviced would soon weaken or ruin the joint. Some joints require more tensile strength and stiffness than rivets can provide.
    • Bolts have a short threaded section and a long unthreaded grip. Screws have a long threaded section and may directly fit the material.
    • Bolts are tightened by turning the nut; the bolt head may be designed for turning.
    • Screws are tightened by turning their head.
    • Replacement fasteners should ideally be identical to the originals. Using like fasteners is important. If duplicates are unavailable, use substitutes with extreme care.
    • Fit classes exist: Class 1 (loose), Class 2 (free), Class 3 (medium), and Class 4 (close).
    • Aircraft bolts are typically Class 3.
    • Class 1 fits can be tightened by hand; Class 4 fits require a wrench. Aircraft screws are usually Class 2 (free) for ease of assembly.
    • Special bolts have an "S" stamp on the head.

    Bolt Identification

    • Bolt identification is based on head shape, securing method, material, and use.
    • AN bolts have markings for manufacturer, material, and type (standard or special purpose).
      • Standard steel AN bolts have "X" or asterisk markings.
      • Corrosion-resistant steel has a single dash.
      • Aluminum alloy has two dashes.
    • Additional data (diameter, length, grip length) are in the part number.
    • NAS bolts have raised or recessed triangles; material markings match AN bolts (raised or recessed).
    • Magnatlux or Zyglo inspected bolts have colored lacquer or distinctive head markings.
    • Aluminum, brass, or insert nuts are identified by metallic luster/color or construction.

    Nuts (Aircraft)

    • Nuts are classified as self-locking or non-self-locking.
    • Non-self-locking nuts require external locking (cotter pins, wire, locknuts).
    • Self-locking nuts have built-in locking mechanisms.
    • Common non-self-locking nuts include: plain nuts, castle nuts, castellated shear nuts, plain hex nuts, light hex nuts, plain checknuts, and wing nuts.
    • Different nut types (e.g., AN310, AN320, AN315, AN335, AN340, AN345, AN316, AN350) have specific applications and features (e.g., strength, safety features). Spring-loaded "self-locking" nuts maintain tightness despite vibration.

    Self-Locking Nuts (Examples)

    • Boots self-locking nuts: A two-part design with a spring-loaded locking mechanism for vibration resistance; load-carrying and locking sections. The spring keeps them spaced so bolts thread through the load-carrying section and then push the locking section and engage. Spring exerts continuous tightening force. Load-carrying section has standard thread strength. Three spring styles and various shapes/sizes.
    • Rol-top nuts: Cadmium-plated steel.
    • Bellows type nuts: Aluminum alloy only.
    • Stainless steel self-locking nuts: Use a compression mechanism to lock. Two-part nut: a case with a beveled locking shoulder, and a threaded insert with a locking shoulder and slotted keyway. The locking shoulder gets wedged/compressed and locks bolt, tighten for lock.
    • Elastic stop nuts: A standard nut with an added nylon collar. The nylon collar creates downward pressure to lock the nut. Nylon is resistant to water damage. When tightened, friction pushes the nylon, creates downward pressure on the load-carrying part, ensuring positive contact between nut and bolt threads. Aircraft bolts are available in aluminum alloy with anodized finish or cadmium-plated steel. Check that material hasn't become brittle. Use only when able to securely turn.

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    Description

    Explore the different types of fasteners used in aircraft assembly, including threaded fasteners, rivets, bolts, and screws. Learn about identification standards like AN, NAS, and MS, as well as the importance of fit classes and proper replacement practices. This quiz is essential for understanding fastening processes in aerospace applications.

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