1-1a-8 Chapter 2

Screws are fasteners with threads that are typically used on aircraft. They are similar to bolts but are designed with a looser thread fit and a shank threaded along the entire length. They are available in different tensile strengths, materials, and head types.

Structural screws are used in primary aircraft structures, like bolts and rivets. They have high tensile strength and are made from materials equivalent to structural bolts. They must be installed with a definite grip.

Machine screws are commonly used in aircraft for non-structural applications. They're available in various head styles and types, including flathead, countersunk, and roundhead, with different slots for screw driver usage.

Self-tapping screws are a type of screw designed to create their own threads in the material being fastened. They are often used in thin materials like sheet metal.

Setscrews are used to hold parts in place by applying pressure. They have a pointed or blunt end with a thread designed to engage a mating hole or groove, preventing rotation.

The head is the portion of the screw where the screwdriver fits.

The body is the section extending from the bottom of the screw's head to the beginning of the screw's threaded portion.

Threads are the helical grooves on the screw that engage a mating thread in the material being fastened, creating a secure connection.

The total length of a screw, measured from the top of the head to the bottom of the threads.

The distance from the underhead bearing surface to the start of the threads.

The length of the screw that extends from the head to the beginning of the threads.

The combined length of the body length and the threaded length.

A type of screw used in general applications, often made from carbon steel, corrosion-resistant steel, or brass.

A machine screw with a round head, often used in applications where a raised head is desired.

A machine screw designated as AN508. It's made of brass and is specifically designed for electrical applications.

A machine screw designated as AN515. It's designed for general purposes and is available with coarse threads.

A machine screw designated as AN520. It's designed for general purposes and has fine threads.

A screw specification indicating a low-carbon steel material with a tensile strength of 69,000 PSI minimum.

A screw specification indicating a medium carbon steel material with a higher tensile strength than Grade 2.

A screw specification indicating a medium carbon steel material with a tensile strength of 120,000 PSI minimum.

A screw specification indicating a medium carbon steel material with a tensile strength of 140,000 PSI minimum.

A screw specification indicating an alloy steel material with a tensile strength of 150,000 PSI minimum.

Steel, Corrosion Resistant. Tensile Strength: 125,000 PSI Min

Bronze, Commercial. Close Tolerance. Tensile Strength: 48,000 PSI Min

Steel, Carbon, Free Machining. Grade 0 to 4. Tensile Strength: 55,000 PSI Min. Rockwell Hardness: B66

Steel, Carbon, Heat Treated. Grade BO. Tensile Strength: 100,000 PSI Min.

Steel, Alloy, Quenched and Tempered. Grade BB. Tensile Strength: 105,000 PSI Min

Steel, Medium Carbon Quenched and Tempered. Grade 0 to 3/4. Tensile Strength: 120,000 PSI Min. Rockwell Hardness: C23-32

Steel, Alloy, Quenched and Tempered. Grade BC. Tensile Strength: 125,000 PSI Min.

Steel, Alloy, Quenched and Tempered. Grade BD. Tensile Strength: 150,000 PSI Min

Steel, 5% Chromium. Grade B5. Tensile Strength: 100,000 PSI Min.

Steel, 12% Chromium. Grade B6. Tensile Strength: 105,000 PSI Min

A screw or bolt made from steel containing 18% chromium and 8% nickel, known for its corrosion resistance.

A screw or bolt made from steel containing 18% chromium and 8% nickel, but also contains columbium to further enhance corrosion resistance.

A screw manufactured to be machinable, meaning it's easier to cut threads and shape.

A screw or bolt made from steel containing 18% chromium and 8% nickel, stabilized with titanium for corrosion resistance.

A screw made from alloy steel, known for its high tensile strength, often used in aerospace applications.

A screw made from alloy steel with a higher tensile strength than Grade B7, exceeding 125,000 PSI minimum.

A screw or bolt made from alloy steel with a minimum tensile strength of 125,000 PSI, commonly used in aerospace and high-stress applications.

A screw or bolt with a special marking to show the material is corrosion-resistant steel.

A screw or bolt with a cross marking indicating it's made from alloy steel with high tensile strength.

A screw or bolt with a recessed triangle marking, showing it has close tolerances for the shank and head, ensuring a precise fit.

A screw or bolt marked with a triangle and a dimple inside, signifying it's high strength and has close tolerances in the shank and head.

A screw or bolt marked with a triangle and an X inside indicating it's made from alloy steel with high strength and has close tolerances in the shank and head.

A screw or bolt with the letter 'R' marking, indicating the threads have been rolled after heat treatment, resulting in a stronger thread.

A screw or bolt marked with two parallel dashes, indicating the material is aluminum alloy.

Socket head screws use a wrench to tighten them. They are designed for applications requiring high strength, precision parts, and compact assembly.

Pan head and truss head screws are used for general purpose applications where the head height is unimportant. They are available with cross-recessed heads only.

These screws are used for temporarily attaching sheet metal for riveting and for permanent assembly of nonstructural assemblies where the ability to install the screws in a blind application is required. They cut their own threads upon installation.

They are available in flathead, socket head, and roundhead styles. They require internal wrenches to drive into tapped holes in the casting after the hole has been underdrilled.

They are used for applications requiring high strength, precision parts, and compact assembly.

They are manufactured from steel or corrosion-resistant steel.

They are available in different sizes and lengths. The first dash number indicates the screw size, and the second dash number indicates the screw length.

They are available in a variety of tensile strengths, materials, and head types.

They are made from aluminum alloy, which is a light-weight metal commonly used in aircraft construction.

They are made from steel that has been treated to resist the effects of corrosion.

These screws are often used in applications where high temperatures are encountered. They are made from a special type of corrosion-resistant steel.

A screw that is designed to create its own threads in the material being fastened. Often used for attaching thin material like sheet metal.

A specific type of screw used for fastening metal parts. It is often used for non-structural applications.

A screw used for fastening parts in primary aircraft structures. They have higher tensile strength and are made from materials similar to bolts.

A screw designed to hold parts in place by applying pressure.

A type of structural screw manufactured from corrosion-resistant steel. It is often used in aircraft applications.

A type of machine screw with a specific head style and diameter.

A screw with a cross-shaped recess for a screwdriver.

A screw that is plated with flash cadmium for corrosion resistance.

A type of screw with a specific material quality and corrosion resistance.

The designation of a screw's diameter and grip length. It often indicates the screw size and length.

The designation used to identify different types of screws based on materials, head style, and other characteristics.

A screw part number indicating its material, strength, head style, and other features.

Designates a 100-degree flathead machine screw and is followed by a number code indicating size and length.

A screw size, specifying the thread diameter. For example, in the part number AN507C428-8, "428" refers to a 1/4-inch diameter screw with 28 threads per inch.

A screw length in inches. For example, in the part number AN507C428-8, "8" indicates a screw length of 1/2-inch.

Corrosion-resistant steel material, typically found in AN507 screws. This material refers to a specialty steel alloy that has been formulated to resist rust and corrosion, increasing durability in environments with moisture exposure.

The maximum height of the screw's head

The maximum tensile strength of the screw material, measured in pounds per square inch (PSI), indicating the force required to pull the screw apart.

The maximum shear strength of the screw material, measured in pounds per square inch (PSI), indicating the force required to break the screw by a shearing force.

A standard for flat and roundhead machine screws, often designated with the prefix "NAS" followed by the number 200 or 202, indicating the head style.

An indication of a brass screw, typically found in NAS200/NAS202 screws.

An indication of cadmium plating applied to the screw.

A standard for flathead machine screws, often accompanied by the prefix "NAS514" followed by a number code for size and length.

A standard for 100-degree flathead machine screws, often designated with the prefix "NAS517" followed by a number code to identify the size and grip length.

A standard for 100-degree flathead machine screws, typically prefixed with "NAS662" followed by a number code indicating size and length.

A standard for roundhead machine screws, designated by the prefix "AN508" followed by numbers for size and length.

Standards for roundhead machine screws, designated by the prefix "AN515" or "AN520", followed by numbers for size and length. AN515 screws are made of steel and are designed for general purposes. AN520 screws are available in aluminum alloy and are also intended for general use.

A type of screw used in non-structural applications, available in various head styles and types, with different slots for screwdriver usage.

A machine screw with a round head, often used when a raised head is desired.

A screw specification indicating a low-carbon steel material with a tensile strength of 69,000 PSI minimum.

A screw specification indicating a medium carbon steel material with a higher tensile strength than Grade 2.

A screw specification indicating a medium carbon steel material with a tensile strength of 120,000 PSI minimum.

A screw specification indicating a medium carbon steel material with a tensile strength of 140,000 PSI minimum.

A screw specification indicating an alloy steel material with a tensile strength of 150,000 PSI minimum.

Screws with a round, slightly domed head. Often used in applications where a raised head is desired.

Screws classified with a letter 'C' before the first dash number, indicating they are made from corrosion-resistant steel.

A type of screw that's not intended to be removed after installation. It's driven into a drilled hole with a hammer, often used for nameplates or sealing drain holes.

The total length of a screw, measured from the top of the head to the bottom of the threads.

The distance from the underhead bearing surface to the start of the threads.

The length of the screw that extends from the head to the beginning of the threads.

The combined length of the body length and the threaded length.

A screw specification indicating a low-carbon steel material with a tensile strength of 69,000 PSI minimum.

A screw specification indicating a medium carbon steel material with a higher tensile strength than Grade 2.

A screw specification indicating a medium carbon steel material with a tensile strength of 120,000 PSI minimum.

A screw specification indicating a medium carbon steel material with a tensile strength of 140,000 PSI minimum.

A screw specification indicating an alloy steel material with a tensile strength of 150,000 PSI minimum.

A 1/4-inch diameter screw, .625 grip, Type II plating, Phillips recess.

A 1/4-inch diameter screw, .625 grip, Type I plating, Frearson recess.

The first dash number indicates the screw size, the second dash number indicates the screw grip and length.

A 1/4-28 screw, 0.500 grip, pan head, cross-recessed, Type II plating.

A 1/4-28 screw, 0.500 grip, pan head, cross-recessed, Type I plating.

The dash number indicates the size and length of the screw.

10-32 aluminum alloy screw, 1/2-inch long, slotted head.

Carbon steel, Federal Specification QQ-S-633.

4-40, carbon steel, slotted-head screw, 1-1/2 inch long.

Carbon steel, Federal Specification QQ-S-633.

The screw size and the hardness of the material being tapped.

A screw specifically designed for use in sheet metal, capable of creating its own threads as it is driven into the material.

A screw used to secure parts in place by applying pressure, often with a pointed or blunt end that engages a mating hole or groove.

A screw with a head that requires a wrench to tighten it, usually made from steel or corrosion-resistant steel. They are designed for high strength, precision applications, and compact assembly.

A type of screw specifically used in aircraft, often made from steel, brass, or aluminum alloy.

A marking on a screw or bolt indicating the material is made of corrosion-resistant steel.

A marking on a screw or bolt indicating it is made of alloy steel with high tensile strength.

A marking on a screw or bolt indicating it has close tolerances for the shank and head, ensuring a precise fit.

A marking on a screw or bolt indicating it is made from alloy steel with high tensile strength and has close tolerances in the shank and head.

A marking on a screw or bolt indicating it is made from alloy steel with high tensile strength and has close tolerances in the shank and head.

A marking on a screw or bolt indicating that the threads have been rolled after heat treatment, making the threads stronger.

A marking on a screw or bolt indicating the material is aluminum alloy.

A type of screw with a flat head, commonly used in applications where a low profile is desired, often with a cross-recessed head.

A screw used to attach parts together temporarily, often with the intention of later replacing the screw with rivets.