CABLE
MAINTENANCE.-Cable
~
control
systems require more maintenance than rigid linkage
systems; therefore, they must be inspected more
thoroughly. Cables must be kept clean and inspected
periodically for broken wires, corrosion, kinking, and
excessive wear.
Broken wires are most apt to occur in lengths of
cable that pass over pulleys or through fairleads. On
certain periodic inspections, cables are checked for
broken wires by passing a cloth along the length of the
cable.
Where the cloth snags the cable is an
indication of one or more broken wires.
WmNG
Your bare hands should NEVER be used to
check for broken wires.
Using your bare
hands to check for broken wires could
result in personal injury.
Tests have proven that control cables may have
broken wires and still be capable of carrying their
designated load.
However, any 7 x 19 cable that
shows more than six broken wires in any l-inch
length, or any 7 x 7 cable that shows more than three
broken wires in any l-inch length, must be replaced.
A maximum of three broken wires per inch is
allowable in the length of cables passing over pulleys,
drums, or through fairleads. Figure 9-20 shows how
to determine if a cable is serviceable.
Corrosion, kinking, and excessive wear should be
given particular attention during cable inspection. If
a cable is found to be kinked or badly worn, it should
A
CABLE
WITH
BROKEN
WIRES
DISTRIBUTED
NOT
OVER
6
IN
I-INCH
D
TANCE
IS
STILL
SERVICEABLE.
THESE
WIRES
ARE
BROKEN.
HIS
IS
A
7
X
19
CONTROL
ABLE
MADE
OF
6
STRANOS
AROUND
1
CENTER
STRAND.
EACH
OF
7
STRANDS
HAS
19
WIRES
MAKING
7
X
19
OR
133
WIRES
IN
ALL.
'A
CABLE
WITH
MORE
THAN
6
WIRES
BROKEN
WITHIN
A
I-INCH
DISTANCE
MUST
BE
REPLACED.
Figure 9-20.-Determining
serviceable cable.
be replaced, even though the number of broken wires
is less than that specified for replacement. If the
surface of the cable is corroded, relieve the tension on
the cable and carefully untwist it to visually inspect
the interior. Any corrosion on the interior strands of
the cable constitutes failure, and the cable must be
replaced. If no internal corrosion is detected, remove
loose, external corrosion with a clean, dry rag or fiber
brush and apply the specified preservative compound.
NOTE: Do not use metal wool or solvents to
clean installed cable. Metal wool will embed
tiny dissimilar metal particles and create
further corrosion problems.
The use of
solvents will
remove the internal
cable
lubricant
and allow the cable strands to
abrade and further corrode.
When a cable is found to be unserviceable and a
spare cable is not available, an exact duplicate of the
damaged cable may be prepared. This will involve
cutting a length of cable to the proper length,
attaching the necessary end fittings, and testing the
assembly.
To determine the proper length to which the new
cable will be cut, you should first determine the
overall length of the finished cable assembly. This
may be accomplished by measuring the old cable
assembly or by reading the measurements provided in
the MIM for the aircraft concerned.
Replacing cables in the aircraft, especially those
routed through inaccessible spaces, can be difficult.
One method is to secure a snaking line to the cable to
be replaced, remove the pulleys from the brackets,
and pull out the old cable while pulling the snaking
line into the cable system run at the same time. Attach
the new cable assembly to the snaking line, and pull
the snaking line out to pull the new assembly into
place. Replace the pulleys and attach the new cable in
the system.
QUICK DISCONNECTS.-Quick
disconnects
are used in cable systems that may require frequent
disconnecting. One type of quick disconnect is made
with steel balls swaged to the ends of the cable,
slipped
into a slotted
bar, and secured with
spring-loaded
sleeves on each end of the bar.
Figure 9-21 shows the procedures for disconnecting
and connecting this type of quick-disconnect fitting.
9-26
