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

1. SCOPE

1.1 Purpose. This 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.

1.2 Background. The philosophical position and technical information presented in this handbook are based upon results of a previous naval study documented in NAVAIR Report AIR-

5181-1000, "Airframe Electrical Grounding Requirements Program Final Report." That study demonstrated that hazards exist during aircraft maintenance and established that there are valid technical reasons to ground aircraft. It also recognized that a rigorous grounding philosophy is necessary to maximize personnel and aircraft safety. Aircraft grounding methods presented in this handbook describe procedures for static grounding of aircraft during all maintenance actions including fueling/de-fueling and ordnance loading or unloading evolutions. The procedures in this handbook apply to both fixed wing and rotary wing aircraft. The grounding methods presented in this handbook make a clear distinction between static grounding and power grounding. Information related to construction of facility radio frequency (RF) grounds, lightning grounds, power safety grounds, and sensitive equipment grounds are addressed in the Naval Facilities Engineering Command (NAVFAC) UFC 3-570-01,Unified Facilities Criteria (UFC) document titled, "Static Electricity and Lightning Protection Systems."

1.3 Structure. This handbook provides guidance on grounding for safety of personnel, aircraft and aircraft equipment. It may also be used for guidance to verify facility ground points.

2. APPLICABLE DOCUMENTS

2.1 General. The documents listed below are not necessarily all of the documents referenced herein, but are those needed to understand the information provided by this handbook.

2.2 Government documents.

2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein.