6.
All cable rigging tensions given must be corrected to ambient temperature in the area where the tension is being checked by using Chart 2701.
7.
See Figure 27-1 for the proper method of adjusting rod ends to prevent possible damage and binding of bearing surface in rod end.
— CAUTION — IF THE FLAPS AND AILERONS ARE BOTH DISCONNECTED FROM THE CONTROL SYSTEM, AND LEFT TO HANG ON THEIR HINGES, BE CAREFUL IN LETTING ONE ROTATE DOWN AFTER HAVING RELEASED THE OTHER, AS THEY WILL “LOCK-UP” AND DAMAGE THEIR SKINS.
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CHART 2701. CABLE TENSION VS. AMBIENT TEMPERATURRE
TEMPERATURE, DEGREES FAHRENHEIT
120 110 100 90 80 70 60 50 40 30
20
Figure 27-1. Rod End Installation Method
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2B8
CONTROL CABLE INSPECTION
Aircraft control cable systems are subject to a variety of environmental conditions and forms of deteriora-tion 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:
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 2A 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 27-2B) when the cable was removed and bent using the techniques depicted in Figure 27-2C.
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 27-3.
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 27-4, is not easily detected unless the strands of the cable are separated. Wear of this type is a result of
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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.
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CORROSION
Carefully examine any cable for corrosion that has a broken wire in a section not in contact with wear pro-ducing airframe components such as pulleys, fairleads, etc. It may be necessary to remove and bend the cable to properly inspect it for internal strand corrosion as this condition is usually not evident on the outer surface of the cable. Replace cable segments if internal strand rust or corrosion is found.
Areas especially conducive to cable corrosion are battery compartments, lavatories, wheel wells, etc., where concentrations of corrosive fumes, vapors, and liquids can accumulate.
– Note – Check all exposed sections of cable for corrosion after a cleaning and/or metal-brightening operation has been accomplished in that area.
CABLE MAINTENANCE
Frequent inspections and preservation measures such as rust prevention treatments for bare cable areas will help to extend cable service life. Where cables pass through fairleads, pressure seals, or over pulleys, remove accumulated heavy coatings of corrosion prevention compound. Provide corrosion protection for these cable sections by lubricating with a light coat of graphite grease or general purpose, low-temperature oil.
– CAUTION – AVOID USE OF VAPOR DEGREASING, STEAM CLEANING, METHYLETHYLKETONE (MEK) OR OTHER SOLVENTS TO REMOVE CORROSION-PREVENTATIVE COMPOUNDS, AS THESE METHODS WILL ALSO REMOVE CABLE INTERNAL LUBRICANT.
CABLE FITTINGS
Check swaged terminal reference marks for an indication of cable slippage within fitting. Inspect fitting assembly for distortion and/or broken strands at the terminal. Assure that all bearings and swivel fittings (bolted or pinned) pivot freely to prevent binding and subsequent failure. Check turnbuckles for proper thread exposure and broken or missing safety wires/clips.
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