amt hardware two

Components included in aircraft hardware

Fasteners and small hardware items used to assemble or repair aircraft

Four common methods of joining aircraft parts

Riveting, bolting, brazing, and welding

Three common standard identification systems for aircraft hardware

AN, NAS, and MS

Class 1 thread fit

Loose fit

Class 2 thread fit

Free fit

Class 3 thread fit

Medium fit, commonly used for aircraft bolts

Class 4 thread fit

Close fit

Thread fit class usually used for aircraft screws

Class 2

Tightening direction for right-hand threads

Clockwise

Tightening direction for left-hand threads

Counterclockwise

Primary application distinction for aircraft bolts versus screws

Bolts are used when higher strength is required, whereas screws are used when strength is less critical

Standard tightening method for a bolt versus a screw

A bolt is typically tightened by turning a nut, whereas a screw is tightened by turning its head

Load types handled by AN general-purpose bolts

Tension and shear

Application requirement for close-tolerance aircraft bolts

Used when a tight drive fit is required

Head marking for NAS close-tolerance bolts

Triangle

Primary application of internal-wrenching bolts

High-strength tension and shear applications

Substitution rule regarding regular AN bolts and internal-wrenching bolts

Regular AN bolts cannot be substituted for internal-wrenching bolts

Clevis bolt loading restriction

Approved for shear loads only; never used for tension loads

Primary function of an eyebolt

Used for external tension loads and as an attachment point

Jo-bolt description

High-strength blind fastener

Main characteristic and disadvantage of a lockbolt

A permanent structural fastener that is difficult to remove

Three types of lockbolts

Pull, stump, and blind

AN bolt code diameter unit measurement

In sixteenths of an inch ($\frac{1}{16}\,\text{in}$)

AN bolt code length unit measurement

In eighths of an inch ($\frac{1}{8}\,\text{in}$)

Material designation letter DD in an AN bolt code

2024 aluminum

Material designation letter C in an AN bolt code

Corrosion-resistant steel

Material composition of an AN bolt with no material letters in its code

Cadmium-plated steel

Meaning of the letter A at the end of an AN bolt part number

Undrilled shank

Requirements for plain aircraft nuts

Must be used with a separate locking device

Primary application and limitation of self-locking nuts

Used where vibration could cause loosening, but generally cannot be used on parts that rotate

Device used to secure castellated (castle) nuts

Cotter pin

Primary purpose of a plain washer

Distributes the load and protects the surface

Primary purpose of a lock washer

Helps prevent fasteners from loosening

Primary purpose of safety wire

Prevents fasteners from loosening due to vibration

Direction safety wire must pull a fastener

In the tightening direction

Primary purpose of quick-release fasteners

Allows fast removal and installation of access covers and panels

Primary joint function of rivets in aircraft structures

Permanent attachment

Most common aircraft rivet alloy designation

2117

Material associated with 5056 alloy rivets

Magnesium

Key characteristic of 2017 and 2024 alloy rivets

High-strength rivets requiring precise heat-treatment timing