FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 18. Conduits | 11-253. Flexible Conduit
AC 43.13-1B
11-253. FLEXIBLE CONDUIT. Flexible
aluminum conduit conforming to Specifica-
tion MIL-C-6136 is available in two types:
Type I, Bare Flexible Conduit, and Type II,
Rubber Covered Flexible Conduit. Flexible
brass conduit conforming to Specification
MIL-C-7931 is available and normally used
instead of flexible aluminum where necessary
to minimize radio interference. Also avail-
able is a plastic flexible tubing. (Reference
MIL-T-8191A.) Flexible conduit may be used
where it is impractical to use rigid conduit,
such as areas that have motion between con-
duit ends or where complex bends are neces-
sary. The use of transparent adhesive tape is
recommended when cutting flexible tubing
with a hacksaw to minimize fraying of the
braid. The tape should be centered over the
cutting reference mark with the saw
9/8/98
cutting through the tape. After cutting the
flexible conduit, the transparent tape should
be removed, the frayed braid ends trimmed,
burrs removed from inside the conduit, and
coupling nut and ferrule installed. Minimum
acceptable bending radii for flexible conduit
are shown in table 11-24.
TABLE 11-24. Minimum bending radii for flexible alu-
minum or brass conduit.
Nominal I.D. of conduit
(inches)
Minimum bending radius
inside (inches)
3/16
1/4
3/8
1/2
5/8
3/4
1
1 1/4
1 1/2
1 3/4
2
2 1/2
2 1/4
2 3/4
3 3/4
3 3/4
3 3/4
4 1/4
5 3/4
8
8 1/4
9
9 3/4
10
11-254.11-259. [RESERVED.]
Page 11-102
Par 11-253