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.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - 30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 - 38 - 39 - 40 - 41 - 42 - 43 - 44 - 45 - 46 - 47 - 48 - 49 - 50 - 51 - 52 - 53 - 54 - 55 - 56 - 57 - 58 - 59 - 60 - 61

MIL-HDBK-274A

FIGURE 2. Possible return path for accumulated charge during remote discharge of clouds.

4.4.1.2.2 Personal contact. A person in contact with an aircraft charged by induction to

60 kV could discharge 9 Joules (J) of energy from the aircraft.

Equation: (2)

Where:

U = i C·V2

= i (0.005µF) · (60 kV)2

= 9J

C = aircraft capacitance to ground (microfarads) V = voltage from aircraft to ground (volts)

U = energy level (Joules)

This level well exceeds the threshold value for lethal shock and could be fatal. To further analyze potential hazards the following equations are used: