Piper COMANCHE PA-24-180 Service Manual page 281

PIPER COMANCHE SERVICE MANUAL
APPENDIX NO. I
Control Cable Inspection
Aircraft control cable systems are subject to a variety of environmental conditions and forms of
deterioration that, with time, may be easy to recognize as wire/strand breakage or the not-so-readily
visible types of wear, corrosion, and/or distortion. The following data may help in detecting the presence
of these conditions:
A. Cable Damage
Critical areas for wire breakage are sections of the cable which pass through fairleads and around
pulleys. To inspect each section which passes over a pulley or through a fairlead, remove cable
from aircraft to the extent necessary to expose that particular section. Examine cables for broken
wires by passing a cloth along length of cable. This will clean the cable for a visual inspection, and
detect broken wires, if the cloth snags on cable. When snags are found, closely examine cable to
determine full extent of damage.
The absence of snags is not positive evidence that broken wires do not exist. Figure 27-lA shows a
cable with broken wires that were not detected by wiping, but were found during a visual
inspection. The damage became readily apparent (Figure 27-IB) when the cable was removed and
bent using the techniques depicted in Figure 27-1C.
B. External Wear Patterns
Wear will normally extend along cable equal to the distance cable moves at that location. Wear may
occur on one side of the cable only or on its entire circumference. Replace flexible and non-flexible
cables when individual wires in each strand appear to blend together (outer wires worn 40-50
percent) as depicted in Figure 27-2.
C. Internal Cable Wear
As wear is taking place on the exterior surface of a cable, the same condition is taking place
internally, particularly in the sections of the cable which pass over pulleys and quadrants. This
condition, shown in Figure 27-3, is not easily detected unless the strands of the cable are separated.
Wear of this type is a result of the relative motion between inner wire surfaces. Under certain
conditions the rate of this type wear can be greater than that occurring on the surface.
Added: 8/15/98
APPENDIX NO. I
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