An Introduction to Military Standards
What is Mil Spec? What are Military Standards?
The terms military standard and military specification are used interchangeably. They can be abbreviated to MIL STD, MIL-STD and mil spec respectively. Military standards have traditionally been applied to anything the military ordered, and these standards crept into many other areas of government procurement and other products built by defense contractors. If it was requisitioned by the Department of Defense, it had to meet military spec, i.e. military standards.
If your drawing or test document says something must meet mil spec 1629, it must meet military standard 1629, abbreviated as MIL-STD-1629 or mil std 1629.
Many military standards predate ISO and ANSI standards in the same areas Military standards on things like documentation and drawings have gradually been incorporated or replaced with standards by groups like ANSI International and the International Standards Organization. Military standards on marking items and packaging remain primarily military specifications, though general industry standards are creeping in.
Military Standards for Drawings and Documentation
MIL-STD-100 was the military standard on engineering drawing practices. MIL-STD-103 gives the standard abbreviations for electrical and electronic terms. MIL-STD-106 lists the mathematical signs and symbols used with regard to the physical sciences.
MIL-STD-12 gives the abbreviations to be used on military and Department of Defense drawings, specifications and technical documents. MIL-STD-8 was the old military standard for dimensioning and tolerancing. MIL-STD-8 was replaced by ASME/ANSI standard Y14.5.
MIL-STD-38784 is the military standard and style guide for technical manuals. This is different from style guides like the Associated Press style guide.
MIL-STD-973 is the DoD standard for configuration management. Configuration Management or CM refers to the process of managing changes to things ranging from drawings to technical specification documents to test procedures. Documents have unique identifiers assigned to them. Changes to documents are reviewed and approved. Updated documents are reviewed before being formally published with a new revision letter and publication date so that readers know that earlier versions exist and when the version they are reading was released. For many newer military and military contractor's drawings, ISO standards for configuration management are specified instead of military standards.
Military Standards for IT
MIL-STD-1815 is the military standard for the ADA programming language. MIL-STD-1840 is the military standard for the automated interchange of technical information. MIL-STD-2096 gives the data requirements of microcircuits.
The majority of other military standards for information technology and programming languages are now drawn from the IEEE and ISO. Circuit cards and test equipment are now programmed in general technical languages, though CATLAS may be used for automated test sets used to verify PCB assembly is properly configured.
Military Standards for Marking and Identifying Objects
MIL-STD-101 gives the color code for pipelines and for compressed gas cylinders. MIL-STD-102 is the standard for anti-friction bearing identification codes. MIL-STD-1247 is the standard for marking hoses and pipes based on their functions and the hazard they pose. MIL-STD-1285 is the standard for marking electrical and electronic parts. MIL-STD-1189 gives the Department of Defense’s standard for bar code symbols.
MIL-STD-129 is the standard for marking items for shipment and storage. Military standard MIL-STD-130 is the standard for identification markings put on U.S. military property.
MIL-STD-1458 is the standard for marking and labeling radioactive materials. MIL-STD-190 is the standard for the identification markings of rubber products.MIL-STD-450 is the standard for signs marking contaminated or dangerous areas.This is similar to ANSI Z535.
MIL-STD-456 is the standard for date codes used on electronic parts, indicating when the part was manufactured. MIL-STD-595 was the standard for colors used in government procurement. This military standard was replaced with federal standard 595C.
Military Standards for Reliability, Safety and Maintainability
MIL-STD-721 gives the definition of terms used for reliability and maintainability used in other DoD standards. MIL-STD-2074 gives the classification of failures for reliability testing. MIL-STD-470 outlines the standards for a maintainability program.
Maintainability is defined as the ability of a design to compartmentalize failures, such as a circuit suffering from an electrical short or with a bullet hole through it able to close off the damaged area and switch to fall back circuits and keep going. The unit is easy to maintain because you don't have to shut it down and take it all the way apart to repair it.
MIL-STD-1390 describes the concept of levels of repair and how to perform a level of repair analysis or LORA. In a level of repair analysis, a logical analysis is performed to determine if it is best to repair an item, replace it or throw it out. The LORA decision must factor in the cost of each outcome as well as the part’s performance. For example, choosing to repair something and put it back in an aircraft may be cheap but may not be safe.
MIL-STD-2084 is the standard for the maintainability of avionic and electronic systems like PCB assemblies and their enclosures when used on aircraft.
MIL-STD-1629 gives the DOD’s procedure for performing a failure mode, effects and criticality analysis. This can also be called an FMEAC analysis. This analysis is the process of determining the root cause of a failure or identifying possible ways a design could fail so that the design could be improved. For example, if a helicopter will fall out of the sky if one of the two wires to the rotors is cut, the solution may be adding another one or two wires.
MIL-STD-756 is the standard for modeling and predicting the reliability of systems. The estimated failure rate of a product can be used to determine if it is reliable enough for military use and test designs for reliability and safety before they are built and tested mechanically. A PCB assembly would be tested to determine if it could still relay data to the pilot if one of the wires or circuit cards burned out.
Military Standards for Packaging and Shipping
MIL-STD-2073 is the DOD standard for military packaging. MIL-STD-648 gives the military’s design criteria for specialized shipping containers. MIL-STD-649 is the standard for preparing aluminum and magnesium products for shipment and storage.
MIL-STD-726 was a standard outlining the requirements for packaging. MIL-STD-726 has been replaced by MIL-STD-2073-2.
MIL-STD-731 outlines the quality of wood members to be used in shipping such as the wood used to make pallets and crates. MIL-STD-3010 describes the test procedures to be used for packaging materials to verify that they can handle the rough handling they will see in the field before military components are boxed up and shipped in them.
Standards for Definitions Used in Other Military Standards
MIL-STD-1313 is the standard for microelectronic terms and definitions. MIL-STD-1332 gives the definitions for tactical terms. MIL-STD-1241 lists the optical terms and definitions used in military standards.
MIL-STD-1309 gives the definitions of terms used for testing, measurement and diagnostics used in all other military standards. MIL-STD-280 gives the definitions used to explain item levels.
MIL-STD-280 also sets the standard for item exchangeability, a technical term for the ability to remove and replace one part with another and have “plug and play” functionality. For example, level 0 generally refers to the top level part while level 1 refers to the items assembled into the design. If level 0 is a helicopter, level 1 could refer to the rotor assembly or motor assembly. Level 2 would be made up of the motor’s components and rotor’s components. For a PCB assembly, PCB enclosures would be level 1 while the final PCB assembly would be level 0.