MIL-HDBK-274 Electrical Grounding For Aircraft SafetyThis handbook has been prepared to provide U.S. Navy and Marine Corps aircraft maintenance and operations personnel with the background and technical details of the different types of aircraft grounds and how they are applied. In addition, this handbook provides background information for aircraft grounding, static electricity theory and how it affects aircraft, and techniques used for measurement of grounding points. This handbook is intended for use by all U.S. Navy and Marine Corps aircraft maintenance and operations personnel for the purposes of ensuring that aircraft are properly and safely grounded. This handbook is for guidance only and cannot be cited as a requirement.

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MIL-HDBK-274A

Radio Frequency (RF) Grounds. RF grounds are grounds that protect systems from voltages and currents induced from internal system generated electromagnetic fields and from external electromagnetic fields.

Static Electricity. An accumulation of electric charge on an insulated body (See Section

4.2 for more detail).

Static/ESD Grounds. Static/electrostatic discharge (ESD) grounds are defined as those having resistances of less than 10,000 ohms referenced to Earth.  Static/ESD grounds are used to dissipate or "bleed" accumulated charges from triboelectric action, particle impingement, or electric field inducement.  This slow bleeding avoids arcing and sparking which may occur from high potential (voltage) electrostatic charges built-up between different electrical potential

points.  Static/ESD currents are typically on the order of microamperes (µA) but occur between points of several thousand volts difference in electrical potential.

Temporary Grounding. In areas where no static or power grounds exist, metal rods may be driven into the ground at points adjacent to the proposed aircraft parking position.

Triboelectric Effects. A type of contact electrification in which certain materials become electrically charged after they come into contact with another different material and are then separated (such as through rubbing).  The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, and other properties.

3.2 Acronyms and abbreviations.

µA                  -     microampere

A                    -     ampere

A/C                -     aircraft

AC                 -     alternating current

ANSI             -     American National Standards Institute

C                    -     Coulomb

DBA              -     Distribution Box Assembly

DC                 -     Direct Current

DoD               -     Department of Defense

DoDD            -     Department of Defense Directive DoDI              -     Department of Defense Instruction EED               -     Electroexplosive Device

EID                -     Electrically Initiated Device

ESD               -     Electrostatic Discharge

FARP             -     Forward Arming and Refueling Point

FOD               -     Foreign Object Damage

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