Fasteners in Aviation

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Aerospace Fastener Applications Part 2
An Aerospace Manufacturing Perspective
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Aerospace Rivets

• Primarily used to fasten aerospace skins to the
  sub-structure
• Concerned mainly with shear and tension loads.
• Two types of rivets
• Solid Rivet
• Blind Rivet

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Aerospace Rivets

• Rivets on the skin of a Boeing 737

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Aerospace Solid Rivets
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Aerospace Solid Rivets

• Universal solid rivets on the skin of a Boeing
  737

• Note that they are not flush with the skin

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Aerospace Solid Rivets

• Countersunk solid rivets on the engine pylon of
  a Boeing 737

• Note that these rivets are flush with the surface

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Aerospace Solid Rivets
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Aerospace Solid Rivets - Identification

• Rivets manufactured in accordance with the AN/MS
  standards are identified by a four part code
• AN or MS specification and head type
• one or two letters that indicate the material
• shank diameter in 1/32nd inch increments
• a dash followed by a number that indicates rivet
  length in 1/16th inch increments.

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Aerospace Solid Rivets - Identification

• Aircraft rivets are made of many materials, and
  come in a wide variety of shapes and sizes
• How do you select the right size?
• How do you select the right material?
• We must know what the part number tells us

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Aerospace Solid Rivets - Identification

• Example rivet identification
• standard universal head solid rivet
• Material 2117-T4 aluminium
• 1/8 inch diameter
• 5/16 inch in length
• Rivet ID either AN470AD4-5 or MS20470AD4-5

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Aerospace Solid Rivets - Identification

• Same rivet, different material1100 aluminium
• AN470A4-5 or MS20470A4-5.
• AN470 or MS20470 denote the specification for
  universal head types
• AD is the material code for 2117-T4
• (A1100, B5056, Ccopper, D2017, DD2024,
  Fstainless and MMonel)
• 4 4/32 or 1/8 inch diameter
• -5 5/16 inch length

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Aerospace Solid Rivet Installation

• Rivet installation summary
• Drill appropriately sized holes
• Deburr holes
• Secure pieces together with Clecos
• Install rivet, buck with rivet gun or use a rivet
  squeezer

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Aerospace Solid Rivet Installation

• .032 2024-T6 sheet aluminum to be joined with
  rivets
• Rivet gun
• Bucking bar
• Drill
• Drill bit and chuck key
• Center punch
• Cleco
• Cleco pliers

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Aerospace Solid Rivet Installation

• Drilling holes with a 30 drill bit
• Use 1/8 rivets with a 30 (.1285) drill bit

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Aerospace Solid Rivet Installation

• Deburr the holes by rotating (by hand) a much
  larger drill bit in the holes
• This removes any metal shavings caused by
  drilling

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Aerospace Solid Rivet Installation

• Position the pieces together and secure using
  Clecos
• Clecos maintain proper alignment of the pieces
  while rivets are being installed

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Aerospace Solid Rivet Installation

• Place the rivet in the hole
• Make sure you are using the correct size,
  material, and type of rivet

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Aerospace Solid Rivet Installation

• Align the rivet gun on the rivet head
• Hold the bucking bar on the opposite end of the
  rivet
• Pull the trigger on the rivet gun to hammer the
  rivet in place

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Aerospace Solid Rivet Installation

• Solid rivets can be installed using a rivet
  squeezer instead of a pneumatic rivet gun
• The squeezer is hand operated
• The squeezer uses various inserts depending on
  the type and size of rivet being installed

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Aerospace Blind Rivets

• Used when you cannot physically access one side
  of the work
• Blind rivets are hollow, and thus weaker than
  solid rivets
• To retain strength of the joint
• stronger material, larger diameter rivets, or
  more are necessary and of course
• 2050 heavier than a solid rivet because of
  steel stem

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Aerospace Blind Rivets
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Aerospace Rivets Fuselage Repair

• Exterior of a riveted patch fuselage skin patch

• Note that solid fasteners are used except in the
  middle of the patch
• Why would you use blind fasteners in this
  application?

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Aerospace Rivets Fuselage Repair

• Interior of a riveted fuselage skin patch

• Because the stringer on the interior of the
  fuselage prevents the bucking a solid rivet
  requires
• Blind rivets are the only option when access is
  restricted

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Quality Assurance of Aerospace Fasteners

• Aerospace Fasteners Material Selection
• Aerospace Fasteners Testing

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Aerospace Fasteners Material Selection

• Background
• Some factors to be considered before material
  selection are
• The max. and min. operating temperatures
• The corrosiveness of the environment
• Fatigue and impact loading
• Always try to use standard fasteners, such as AN,
  MS, MIL, NAS, SAE

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Aerospace Fasteners Material Selection

• Alloy Steels
• Aluminum
• Titanium
• Stainless Steel
• Superalloys

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Aerospace Fasteners Material Selection

• Aluminum is the predominant material used in the
  manufacture of commercial aircraft.
• Table 3 lists the typical aluminum alloys used in
  commercial aircraft.

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Basic Aerospace Fasteners Application

• The basic applications (or needs) for aerospace
  fasteners are
• Shear
• Tension
• Fatigue
• Fuel tightness
• High temperature
• Corrosion control

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Aerospace Fasteners Testing

• Analyzing a Joint
• Calculate all the load required for each type of
  joint failure
• Rivet Shear
• Sheet Tensile
• Bearing
• Sheet Shear
• Failure will occur in the mode that corresponds
  with the lowest load carrying capability.

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Aerospace Fastener Standardization

• Most aerospace hardware is manufactured per
  government standards
• The three most common aircraft fastener standards
  used are
• AN Air Force/Navy
• NAS National Aerospace Standards
• MS Military Standards

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Common Standardized Fasteners

• Bolts
• Nuts
• Washers
• Turnbuckles
• Cotter pins
• Screws
• Rivets
• Plumbing fittings (pipes and tubes)