FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 15. Grounding and Bonding | 11-190. Creepage Distance
9/8/98
AC 43.13-1B
11-189. BONDING JUMPER INSTAL-
LATIONS. Bonding jumpers should be made
as short as practicable, and installed in such a
manner that the resistance of each connection
does not exceed .003 ohm. The jumper should
not interfere with the operation of movable
aircraft elements, such as surface controls, nor
should normal movement of these elements re
sult in damage to the bonding jumper.
a. Bonding Connections. To ensure a
low-resistance connection, nonconducting fin
ishes, such as paint and anodizing films,
should be removed from the attachment sur
face to be contacted by the bonding terminal.
On aluminum surfaces, a suitable conductive
chemical surface treatment, such as Alodine,
should be applied to the surfaces within
24 hours of the removal of the original finish.
Refer to SAE, ARP 1870 for detailed instruc
tions. Electric wiring should not be grounded
directly to magnesium parts.
b. Corrosion Protection. One of the
more frequent causes of failures in electrical
system bonding and grounding is corrosion.
Aircraft operating near salt water are particu
larly vulnerable to this failure mode. Because
bonding and grounding connections may in
volve a variety of materials and finishes, it is
important to protect completely against dis
similar metal corrosion. The areas around
completed connections should be post-finished
in accordance with the original finish require
ments or with some other suitable protective
finish within 24 hours of the cleaning process.
In applications exposed to salt spray environ
ment, a suitable noncorrosive sealant, such as
one conforming to MIL-S-8802, should be
used to seal dissimilar metals for protection
from exposure to the atmosphere.
c. Corrosion Prevention. Electrolytic
action may rapidly corrode a bonding connec
tion if suitable precautions are not taken.
Aluminum alloy jumpers are recommended for
most cases; however, copper jumpers should
be used to bond together parts made of stain
less steel, cadmium plated steel, copper, brass,
or bronze. Where contact between dissimilar
metals cannot be avoided, the choice of jumper
and hardware should be such that corrosion is
minimized, and the part likely to corrode
would be the jumper or associated hardware.
Tables 11-14 through 11-16 and figures 11-20
through 11-22 show the proper hardware com
binations for making a bond connection. At
locations where finishes are removed, a pro
tective finish should be applied to the com
pleted connection to prevent subsequent
corrosion.
d. Bonding Jumper Attachment. The
use of solder to attach bonding jumpers should
be avoided. Tubular members should be
bonded by means of clamps to which the
jumper is attached. Proper choice of clamp
material should minimize the probability of
corrosion.
e. Ground Return Connection. When
bonding jumpers carry substantial ground re
turn current, the current rating of the jumper
should be determined to be adequate and that
a negligible voltage drop is produced.
11-190. CREEPAGE DISTANCE. Care
should be used in the selection of electrical
components to ensure that electrical clearance
and creepage distance along surfaces between
adjacent terminals, at different potentials, and
between these terminals and adjacent ground
surfaces are adequate for the voltages in
volved.
Par 11-189
Page 11-75