TM 1-1500-204-23-1
All aircraft parked in a hangar must be
grounded at all times.
To
prevent
accidental
falls,
appropriate
maintenance platforms/safety stands or any
other approved locally procured/manufactured
safety stands/restraint equipment will be used
when working (above 10 feet) on aircraft in a
non-tactical environment.
b.
Earth Grounds. An earth ground (electrode) is a
conductive pipe or rod made of galvanized iron,
galvanized steel, or copperweld steel. The rod regularly
used for grounding is Rod, Ground: MX-148G Line Item
Number (LIN) S08698, National/NATO Stock Number
(NSN) 5975-00-224-5260. This ground rod is 3/4 inch in
diameter and 6 feet long, and it is made of galvanized
steel. It has one pointed end to be driven into the earth
and a bolt and nut at the other end for connecting a
grounding cable.
(1)
Use of earth grounds. The rod is driven
into the earth far enough to reach below the permanent
ground-moisture level. On the apron or ramp of a fixed
airfield, the top of the rod should be level with the
surrounding surface, at other types of facilities, the top
of the rod should be either low enough or high enough
so that people will not trip over it. If the top of the rod is
level with the surrounding surface, an area around the
top of the rod must be dished out so ground cable clips
can be attached to the rod.
(2)
Marking of earth grounds. A yellow circle
18 inches in diameter, with a 2-inch black border
surrounding it, should encircle each rod that is installed
in a hard surface. These circles should be painted on.
The words STATIC GROUND CONNECTION and a
numeric or alphanumeric identification of the rod should
be stenciled in black on the yellow circle. The number
and spacing of fixed rods should be determined by the
requirements of the local situation. Markings of this type
are not required for temporary ground rods.
c.
Earth Ground Testing. The electrical resistance
of each grounding system should be as low as possible
but not greater than 10,000 ohms. A log must be kept
for airfields to show the identification of each rod, the
date tested, and the reading in ohms. If the measured
resistance of a rod is greater than 10,000 ohms, the rod
should immediately be marked DEFECTIVE-DO NOT
USE and it should be removed or replaced as soon as
possible. A log is not required at temporary refueling
points.
(1)
Frequency of testing. Each ground rod
must be inspected when it is installed. Ground wires are
inspected monthly. The grounding system must be
inspected and tested annually or when there is a
possibility of mechanical damage. If any damage is
found, it must be repaired immediately.
(2)
Method of testing. Ground rods are tested
with a multimeter (Multimeter: TS-352B/U, LIN M81372,
NSN 6625-00-553-0142). Refer to FM 10-68 for specific
procedures when testing ground rods.
d.
Fabrication of Ground Cable. Fabricate static
grounding cable assembly, as shown in figure 3-1, using
the following procedures:
(1)
Cut wire rope (figure 3-1, 1) to length
needed.
(2)
If coated wire rope (1) is used; remove ¾
inch of coating from each end.
(3)
Loosen set screws (4) in clip (5).
(4)
Insert wire rope (1) into handle of clip (5)
and tighten set screws (4).
(5)
Insert unattached end of wire rope (1)
through cap (2). Rope will extend past end of cap.
(6)
Screw cap (2) into plug (3).
(7)
If desired, clips (5) may be attached to
both ends of wire rope (1) with a plug (3) attached to
handle of one of the clips as follows:
(a)
Cut short length of wire rope to attach
plug to clip.
(b)
Assemble items for alternate configuration
as in (2) through (6) above. See detail A for view of
alternate cable assembly.
NOTE
Never fasten electrical clip to a
painted surface.
(8)
Insert plug into receptacle on aircraft.
Attach clip to grounding stake.
(9)
Attach warning streamers, NAS 1756-12
or MS 51700-12, to coated wire rope.
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