Aircraft Rivets
  • Rivet Codes - A rivet is any type of fastener that obtains its clamping action by having one of its ends mechanically upset.
    • Airforce Navy - AN
    • Military Standards 20 - MS20
    • AN 470 AD 4 - 5
      • First component of the system denotes the numbering system used (AN/MS20)
      • The second component, the 3 digit number, denotes the style of the rivet head
        • Universal - 470
        • Countersunk- 426
          • To ensure head-to-gunset contact, it is recommended that the countersink head protrude about .005-.007 of an inch from the skin of the aircraft.
            • To smooth it after installation, use a microshaver.
        • Flat head - 442
        • Round Head - 455
      • The third is a 1 or 2 digit code representing the alloy in the rivet.
        • A - 1100 - Pure aluminum - Plain Head
          • Lacks sufficient strength for structural applications
          • Used on Fairings, Engine Baffles, and Furnishings.
          • Is driven cold so shear strength increases because of cold working.
        • AD - 2117 - Copper Alloy - Dimple Head
          • High strength and shock resistance
          • Most widely used for manufacturers and Maintenance
        • B - 5056 - Magnesium - Raised Cross
          • Contain about 5% magnesium
          • Maximum sheer strength is 28,000 PSI
        • D - 2017- Copper Alloy- Icebox rivets - Raised do
          • Crack free rivet with shear strength of 34KSI
          • Icebox rivets - Kept at freezing temperatures (annealed state) until ready to use. They become hard when they warm up to room temperature.
        • DD - 2024 - Copper Alloy - Icebox rivets - Two Raised Dots
        • E - 7050 - Zinc Alloy - Raised Ring
          • Has been percipitation heat treated
        • Staineless steel rivets are used for fastening corrosion resistant steel sheets in applications such as firewalls and exhaust shrouds
          • they have no markings
        • Monel rivets are identified with two recessed dimples in their head.
          • They are used in place of stainless steel rivets where their lower sheer strength is not a detriment.
      • The fourth is the shank diameter, indicated in 1/32 of an inch
      • The fifth is the length, indicated in 1/16 of an inch
    • Head Design - the two standards used are universal and countersunk
      • Counter Sinking - a process in which the metal in the top sheet is cut away in the shape of the rivet head.
      • Dimpling - A process that mechanically dents the sheets being joined to accomidate the rivet head.
      • Crown Flush Rivets - have a slightly crowned heda to allow full contact with the gun-set
        • It forms a fully cold worked rivet that needs no microshaving
  • Special Rivets
    • Blind Rivets - are installed with access to only one end of the rivet.
    • Pop Rivets - have limited use on aircraft and are never used for structural repairs.
      • Useful for temporarily lining up holes.
      • Available in flat head, countersunk head, and modified flush heads with standard diameters of 1/8, 5/32, and 3/16
      • Made from soft aluminum alloy, copper, steel, and monel.
    • Friction Lock Rivets (Cherry Friction lock Rivets)
      • Still used for repairing light aircraft
      • Available in universal and 100 degree countersunk head styles and 1/8, 5/32, 3/16 inch diameters
        • larger sizes can be specifically ordered in sizes up to 5/16 in
      • A friction lock Can Not replace a solid shank rivet size for size it must be at least one size larger in diameter
    • Mechanical-Lock Rivets - Designed to prevent center stem of a rivet from falling out as a result of vibration encountered during aircraft operation by permanently locking the stem into place and vibration can not shake it loose.
      • Huck-Locks - were the first mechanical-lock rivets
        • Used as structural replacements for solid shank rivets.
        • Available in for standard diameters 1/8, 5/32, 3/16 and 1/4 in and come in three different alloy combinations:
          • 5056 sleeve with a 2024 pin
          • A-286 sleeve with an A-286 pin
          • Monel 400 sleeve with a A-286 pin
      • Cherrylocks - the center stem is locked into place with a lock ring resulting in shear and bearing strengths that are high enough to allow them to be used for solid shank rivets.
        • Two head styles; 100 degree countersunk and universal with diameters of 1/8, 5/32 and 3/16 of an inch with an oversize for each of 1/64
        • Made of 2017 aluminum alloy, 5056 aluminum alloy, Monel, or stainless steel.
        • a disadvantage is that if a rivet is too short for an application, the lock ring sets prematurely resulting in a malformed shank header.
      • Olympic-loks - a light weight spindle type blind rivet, with a lock ring stowed at the head.
        • Head styles are universal, 100 degree flush, and 100 degree flush shear. Diameters are 1/8, 5/32 and 3/16 inch
        • Alloys are 2017-T4, A-286, 5056, and Monel.
      • Cherry Max - IS strong enough to replace solid shank rivets, size for size.
        • Composed of five main parts; Pulling stem, a driving anvil, a safe lock locking collar, a rivet sleeve, and a bulbed blind head.
        • Available in universal and countersunk head styles in diameters of 1/8, 5/32, 3/15, and 1/4
        • Sleeve is made from 5056, Monel, and inco 600
        • Stems are made from alloy steel, CRES, and inco x-750
        • The ultimate sheer strength is 50ksi to 70ksi at temperatures of 250-1400 degrees F
      • Removal of mechanical-lock rivets - (all brands of lock rivets are removed using the same technique)
        • You must first file a flat spot on the rivet's center stem.
        • a center punch is used to punch out the stem so the lock ring can be drilled out
        • then you can tap out the remaining stem
        • Then drill out the remaining head
    • Hi-Shear rivets
      • Has the same strength characteristics as a high strength bolt
      • It's secured by a crushing collar
      • Available in two head styles flat and countersunk.
      • Made to withstand high shear loads
      • Made from steel alloy having the same tensile strength as an equal size AN bolt
  • Special Fasteners
    • Lock Bolts There are three type of lock-bolts used in aviation
      • Pull-type Lockbolt - Has a pulling stem on which a pneumatic installation gun fits. The gun pulls the materials together and then drives the locking collar into the grooves of the lock-bolt. Once secure the gun fractures the pulling pin at it's breaking point
      • Blind-type Lockbolt - To install a blind lock-bolt, it is placed into a blind hole and an installation gun is placed over the pulling stem. As the gun pulls the stem, a blind head forms and pulls the materials together. Once the materials are pulled tightly, a locking collar locks the bolt in place and the stem is broken off.
      • Stump-type Lockbolts - Is installed in places where there is not enough room to use the standard pulling tool. The tool is similar to that used in the installation of Hi-Shear rivets.
        • Available for both shear and tension applications. With shear lockbolts, the head is kept thin and there are only two grooves provided
        • The locking collars used on both shear and tension bolts are color coded for easy identification
    • Hi-Loks - Manufactured in several different alloys such as titanium, stainless steel, and aluminum
      • Posses sufficient strength to withstnd bearing and shearing loads, and are available with flat and countersunk heads.
      • the threads are compatible with standard AN bolts and nuts.
    • Hi-Lites - Is made from lighter materials and has a shorter transition from the threaded section to the shank. It's main advantage is its high strength to weight ratio.
      • Available in 3/16 - 3/8 in
      • Installed with either a Hi-lok lockiing collar or a swaged collar
    • Cherrybucks - Is a one-piece special fastener that combines two titanium alloys which are bonded together to form a strong structural fastener
      • Composed of 6AL-4V alloy while Ti-Cb alloy is used in the lower shank.
      • Since there is only once piece these are safe to install inside jet air intakes
    • Taper-Lok - Is the strongest special fasteners used in aircraft
      • They exert a force on the conical walls of a hole. It mimics the action of a driven solid shank rivet, however a taper-lok does this without shank swelling.
    • Hi-Tigue - Has a bead that encircles the bottom of its shank and is a further advancement in special fastener design
      • Available in aluminum, titanium, and stainless steel alloys. The collars are available as sealing, or non-sealing
    • Jo-Bolts - Used in close-tolerance holes where strength requirements are high but physical clearance precludes the use of standard AN, MS, or NAS bolts.
    • Removal of special fasteners - Split the collar with a small cape chisel. Knock away the two halves and tap the fastener from the hole.
    • Threaded Rivets - Rivnuts - Use to attach rubber deicer boots to aircraft wing and tail surfaces.
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