Aerospace, Aviation Metals Review

Metals and other materials used within aerospace / aviation applications are typically the same materials used in other industries. Although the design requirements for aerospace and commercial products may differ significantly, the required design values for the strength of materials and elements and other needed material characteristics are often identical.

Metals and other materials used within aerospace (military) are governed by MIL-HDBK-5 superceded by DOR/FAA/AR-MMPDS-01 Metallic Materials Properties and Standardization. DOR/FAA/AR-MMPDS-01 is technically identical to Mil-Hdbk-5J. Commercial and industrial applications may use the identical material standard identification or reference standard number identifier.

Engineering design references for data and various test methods are listed within DOR/FAA/AR-MMPDS-01 and contains general requirements which in combination with the specific material specifications set the requirements for structural design, analysis and testing of fixed and rotary wing aircraft.

Other controlling specifications for aerospace/aviation metals and materials are the tracability requirements defined by MIL-STD -130. This tracability requirements standard provides the criteria by which companies develop specific item identification marking requirements for their products to track the materials pedigree.

Aviation Federal Aviation Standards (FAA):

The FAA requires that the structural strength and integrity of type-certificated aircraft conform to all airworthiness requirements. These requirements apply to performance, structural strength, and integrity as well flight characteristics. To meet these requirements, each aircraft must meet the same standards. To accomplish standardization, all materials and hardware must be manufactured to a standard of quality. Specifications and standards for aircraft hardware are usually identified by the organization that originated them. Some of the common standardizing organizations include:

AMS - Aeronautical Material Specifications
AN - Air Force-Navy
AND - Air Force-Navy Design
AS - Aeronautical Standard
ASA - American Standards Association
ASTM - American Society for Testing Materials
MS - Military Standard
NAF - Naval Aircraft Factory
NAS - National Aerospace Standard
SAE - Society of Automotive Engineers

Example: When a MS20426-AD4-6 rivet is required, the specifications have already been written for it in the Military Standard (MS) specifications. That information is available to the aircraft manufacturers and to the rivet manufacturers as well as to the mechanic. The specifications designate the material to be used as well as the head type, diameter, and length of the rivet. The use of standardized materials in the production of aircraft makes each aircraft exactly the same as the previous one and makes them less expensive to build.

Typical Material Applications in Aviation and Aerospace:

Aluminum and Aluminum Alloys:

Typical sheet metal applications include alloys of 2024, 3003, 2018 and others.
Structural applications may use 7075, 6061, 6063.

Steel Alloys:

Though a wide range of carbon and alloy steels are used the following represent typical alloys in selected applications

31xx - 44xx Nickel and Molybdenum steel for high fatique and other high strength applications, such as hydrualic components, engine componets, etc.

Carbon steels: 11xx, 12xx and 13xx for load being application such as bracket, securing harware on selected components.

Other engineering materials include:

Brass
Stainless Steel
Inconel
Monel
Magnesium
Copper and Copper Alloys
Others

Nonmetallic Aircraft Materials:

The use of magnesium, plastic, fabric, and wood in aircraft construction has nearly disappeared since the mid-1950s. Aluminum has also greatly diminished in use, from 80 percent of airframes in 1950 to about 15 percent aluminum and aluminum alloys today for airframe construction. Replacing those materials are nonmetallic aircraft materials, such as reinforced plastics and advanced composites.