depot-level repair, the Aircraft Intermediate
wire. Each group of wires twisted together forms a
Maintenance Department (AIMD) will perform a
strand. A group of strands twisted around a central core
visual inspection of the hardware for missing or
is known as a wire rope or cable. A filler wire is a wire
damaged components. Upon completion of the
used to fill the voids between wires in a strand and
inspection, the AIMD will tag all equipment in
between strands in a wire rope. They provide stability
accordance with the Inspection and Proofload Testing
to the shape of the strand or wire rope with little
of Lifting Slings and Restraining Devices for Aircraft
strength contribution. Wire rope construction is
and Related Components manual, NAVAIR 17-1-114.
designated by two numbers. The first being the number
of strands in a cable, and the second being the number
Preinstallation Inspection
of wires in each strand. The following wire rope
constructions are used in the fabrication of aircraft
Before each use, or once a month as in the case of
hoisting slings. See figure 1-22.
emergency handling slings, a complete visual
A 7 7 wire rope consists of six strands of seven
inspection of the wire rope, fabric or webbing,
wires each twisted around a single core strand of seven
structural steel or aluminum, and chain slings must be
wires. The 7 7 construction is used on wire ropes
performed.
measuring 1/16 and 3/32 inch in diameter. Similarly,
7 19 wire rope is constructed with six strands of 19
wires each twisted about a core strand also containing
WARNING
19 wires. The 7 19 wire ropes measure from 1/8 to 3/8
inch in diameter. A 6 19 independent wire rope core
Slings that fail to pass the inspections, or slings
(IWRC) cable consists of six strands, each containing
suspected of having been used during hoisting
19 wires twisted about a core that is of a 7 7
operations beyond the rated capacity of the sling, will
construction. The 6 19 (IWRC) wire rope measures
not be used under any circumstance. Unserviceable
from 7/16 to 1 1/2 inches in diameter. During the
slings are forwarded to the applicable Aircraft
inspection of a wire rope, the measurements of the
Intermediate Maintenance Department for further
diameter and lay length (pitch length) often lead to
analysis and disposition.
confusion. The diameter and lay length are defined as
follows:
WIRE ROPE.--To assist in understanding
1. Diameter. The diameter of a wire rope is the
various inspection criteria for wire rope, a basic
diameter of a circle circumscribed around the cable
knowledge of wire rope construction is required. Each
individual cylindrical steel rod or thread is known as a
Figure 1-22.--Cross sections of wire rope.
1-27
