Question: Aviation Bolts What Does The A Mean After The Bolt Number?

What does an stand for in aviation hardware?

AN fasteners are the industry standard for aircraft, and the name “AN” stands for Army/Navy. It is an indicator that the nuts are made to very specific standards to stand up to the toughest jobs without faltering. These nuts are made to military specifications.

What is the meaning of letter A in the bolt coding?

For example, in the bolt part number AN3DD5A, the “AN” designates that it is an Air Force-Navy Standard bolt, the “3” indicates the diameter in sixteenths of an inch (3/16), the “DD” indicates the material is 2024 aluminum alloy.

How do you identify aircraft bolts?

AN-type aircraft bolts can be identified by the code markings on the bolt heads. The markings generally denote the bolt manufacturer, the material of which the bolt is made, and whether the bolt is a standard AN-type or a special purpose bolt.

How do you read a bolt part number?

The series number (20004) indicates the bolt class and diameter in sixteenths of an inch (internal-wrenching, 1/4-inch diameter). The letter H before the dash number indicates that the bolt has a drilled head for safetying. The dash number (9) indicates the bolt grip in sixteenths of an inch.

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What grade are NAS bolts?

Common NAS and Mil-Spec screw types include cap screws, machine screws, set screws, and tapping screws. The default metal choice for most NAS screws is Grade 5 steel that can be plated with other metals. Elite Fasteners distributes flat head screws, flat head machine screws, plain cup point screws, and more.

What grade are an Bolts?

The most common grading system used for bolts in the U.S. is the SAE system, but you can find metric grading systems as well. There are several grades of bolts but the three common grades for SAE are 2, 5 and 8. The common class ( grades ) for metric are 5.8, 8.8, 10.9 and 12.9. Each grade has a specific bolt strength.

What is the metric equivalent to Grade 8?

Metric Bolt Conversion

Metric Nut Class SAE J429 Normally Used ASTM Grades
5.8 5 .
8.8 8 A325,A449
9.8 9 A193,B7 and B16
10.9 10 or 12 A490,A354, Grade 8D


What does a triangle mean on a bolt head?

The Triangle means it is a Close Tolerance bolt.

What are close tolerance bolts?

Close tolerance bolts are machined more accurately than general purpose bolts and they are used in applications requiring a very tight fit. Close tolerance bolts can be either AN or NAS and typically have a head marking consisting of a raised or recessed triangle.

What size is a AN3 bolt?

AN3 bolts have a 10-32 thread with a 3/16″ shank diameter. All sizes of AN3 bolts have a 0.406 inch thread length, regardless of grip length.

What bolt means?

(Entry 1 of 5) 1a: a lightning stroke also: thunderbolt. b: a shaft or missile designed to be shot from a crossbow or catapult especially: a short stout usually blunt-headed arrow. 2a: a wood or metal bar or rod used to fasten a door.

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How can you tell if a bolt is metric or imperial?

Telling the difference between a metric and imperial bolt is easy. If the bolt has lines on the head its standard or imperial. If the bolt has numbers on the head then its metric. These markings indicate how strong the bolt is they call this tensile strength.

How do you determine bolt length?

Fastener length is measured from where the material surface is assumed to be, to the end of the fastener. For fasteners where the head usually sits above the surface, the measurement is from directly under the head to the end of the fastener.

How can you tell if a bolt is metric?

The metric screw thread is identified by the capital letter M, followed by the nominal diameter. Metric threads are measured by the distance between two adjacent threads in millimeters (pitch). Threads on a standard (inch based) fastener are measured by counting the number of threads per inch.

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