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

TABLE VI. Grounding matrix for shore-based operations.

*Aircraft Grounding Matrix for Shore-based Operations
Aircraft Operation	Flight Line (Designated grounding point)	Hangar (Designated grounding point)	FARP (Designated grounding point)
	Certified Static Ground or Mooring Padeye (Note 1, 2)	Certified Power Ground identified IAW 5.2 and 5.5, and indicating less than 25 ohms resistance (Note 3)	Certified Static Ground, mooring padeye or grounding rod installed IAW 5.9.2, Temporary Grounding (Note 1, 2, 7)
Parked without External Power	x	x	x
Maintenance performed without External Power	x	x	x
MEPP external power applied; Diesel Driven Generator (for example. NC-8, NC-10) (Note 4)	x	x	x
MEPP external power applied; Electric Driven Generator (for example,. MMG) (Note 4)	NIA	x	NIA
Hangar Power Applied	NIA	x	NIA
FLEDS (Flight Line Electric Distribution System) (Note 5)	x	NIA	NIA
FuelingIDefueling (Note 6 & 7)	x	NIA	x
Ordnance LoadIDownload	x	NIA	x
Vertical Replenishment (Note 1, 7)	x	NIA	x

*Refer to NATOPS Flight Manual or MIM for detailed grounding instructions of specific

aircraft.

NOTES:

1. When grounding to a padeye, good metal to metal contact is recommended. This can be obtained by grinding the clamp teeth into the padeye to ensure the connection is free of paint, corrosion and dirt.

2. A Certified Static Ground will have less than 10,000 ohms resistance referenced to