9/8/98 AC 43.13-1B

Par 7-140 Page 7-27

SECTION 8. INSPECTION AND REPAIR OF CONTROL CABLESAND TURNBUCKLES

7-140. GENERAL. Aircraft control cablesare generally fabricated from carbon steel orcorrosion-resistant steel wire of either flexibleor nonflexible-type construction.

7-141. CABLE DEFINITIONS. The fol-lowing cable components are defined in accor-dance with Military SpecificationsMIL-W-83420, MIL-C-18375, andMIL-W-87161.

a. Wire Center. The center of all strandsshall be an individual wire and shall be desig-nated as a wire center.

b. Strand Center or Core. A strand cen-ter is a single, straight strand made of pre-formed wires, similar to the other strandscomprising the cable, in arrangement andnumber of wires.

c. Independent Wire Rope Center(IWRC) 7 by 7. A 7 by 7 independent wirerope center as specified herein shall consist ofa cable or wire rope of six strands of sevenwires each, twisted or laid around a strandcenter or core consisting of seven wires. 7-142. FLEXIBLE CABLES. Flexible,preformed, carbon steel, Type I, composition Acables, MIL-W-83420, are manufactured fromsteel made by the acid-open-hearth, basic-openhearth, or electric-furnace process. The wireused is coated with pure tin or zinc. Flexible,preformed, corrosion-resistant, Type I, compo-sition B cables, MIL-W-87161,MIL-W-83420, and MIL-C-18375 are manu-factured from steel made by the electric-furnace process. (See table 7-3 and fig-ure 7-8.) These cables are of the 3 by 7,7 by 7, 7 by 19, or 6 by 19 IWRC construction,according to the diameter as specified in ta-ble 7-3. The 3 by 7 cable consists of three

strands of seven wires each. There is no corein this construction. The 3 by 7 cable has alength of lay of not more than eight times orless than five times the nominal cable diame-ter. The 7 by 7 cable consists of six strands, ofseven wires each, laid around a center strandof seven wires. The wires are laid so as to de-velop a cable which has the greatest bendingand wearing properties. The 7 by 7 cable has alength of lay of not more than eight times orless than six times the cable diameter. The7 by 19 cable consists of six strands laidaround a center strand in a clockwise direction.The wires composing the seven individualstrands are laid around a center wire in twolayers. The center core strand consists of a layof six wires laid around the central wire in aclockwise direction and a layer of 12 wires laidaround this in a clockwise direction. The sixouter strands of the cable consist of a layer ofsix wires laid around the center wire in acounterclockwise direction and a layer of12 wires laid around this in a counterclockwisedirection. The 6 by 19 cable consists of sixstrands of 19 wires each, laid around a 7 by 7.MIL-C-18375 cable, although not as strong asMIL-W-83420, is equal in corrosion resistanceand superior in non-magnetic and coefficientof thermal expansion properties. 7-143. NYLON-COATED CABLES.

a. Nylon-coated cable is made by ex-truding a flexible nylon coating over corro-sion-resistant steel (CRES) cable. The bareCRES cable must conform and be qualified toMIL-W-83420. After coating, the jacketed ca-ble must still conform to MIL-W-83420.

b. The service life of nylon-coated cableis much greater than the service life of thesame cable when used bare. Most cable wearoccurs at pulleys where the cable bends. Wear

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TABLE 7-3. Flexible cable construction and physical properties.

MINIMUM BREAKING STRENGTH (Pounds)

NOMINALDIAMETEROF WIRE

ROPECABLE

CONSTRUCTIONTOLERANCE

ONDIAMETER

(PLUS ONLY)

ALLOWABLEINCREASE

OFDIAMETER

ATCUT END

MIL-W-83420

COMP A

MIL-W-83420

COMP B(CRES)

MIL-C-18375

(CRES)

INCHES INCHES INCHES LBS LBS LBS1/323/641/161/163/323/321/8

5/323/167/321/4

9/325/1611/323/8

7/161/2

9/165/83/47/8

11 - 1/81 - 1/41 - 3/81 - 1/2

3 x 77 x 77 x 77 x 197 x 77 x 197 x 197 x 197 x 197 x 197 x 197 x 197 x 197 x 197 x 196 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC6 x 19 IWRC

0.0060.0080.0100.0100.0120.0120.0140.0160.0180.0180.0180.0200.0220.0240.0260.0300.0330.0360.0390.0450.0480.0500.0540.0570.0600.062

0.0060.0080.0090.0090.0100.0100.0110.0170.0190.0200.0210.0230.0240.0250.0270.0300.0330.0360.0390.0450.0480.0500.0540.0570.0600.062

110270480480920

1,0002,0002,8004,2005,6007,0008,0009,800

12,50014,40017,60022,80028,50035,00049,60066,50085,400

106,400129,400153,600180,500

110270480480920920

1,7602,4003,7005,0006,4007,8009,000

12,00016,30022,80028,50035,00049,60066,50085,400

106,400129,400153,600180,500

360

700

1,3002,0002,9003,8004,9006,1007,600

11,00014,90019,30024,30030,10042,90058,00075,200

is caused by friction between strands and be-tween wires. In bare cable, this is aggravatedby dirt and grit working its way into the cable;and the lubricant working its way out leavingdry, dirty wires rubbing against each other. Inlong, straight runs of cable, vibration work-hardens the wires causing the brittle wires tofracture with eventual failure of the cable.

c. The nylon-jacket protects the cable ina threefold manner. It keeps the lubricant fromoozing out and evaporating, it keeps dirt andgrit out, and it dampens the vibrations,

thereby, greatly reducing their effect on the ca-ble.

7-144. NONFLEXIBLE CABLES. (Referto table 7-4 and figure 7-9.) Nonflexible, pre-formed, carbon steel cables, MIL-W-87161,composition A, are manufactured by the sameprocesses as MIL-W-83420, composition B,flexible corrosion-resistant steel cables. Thenonflexible steel cables are of the 1 by 7(Type I) or 1 by 19 (Type II) construction ac-cording to the diameter as specified in ta-ble 7-4. The 1 by 7 cable consists of six

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Par 7-144 Page 7-29

FIGURE 7-8. Flexible cable cross section.

TABLE 7-4. Nonflexible cable construction and physical properties.

STRANDTYPE

NOMINALDIAMETER

OFWIRE

STRANDIn.

TOLERANCEON

DIAMETER(Plus Only)

In.

ALLOWABLEINCREASE

INDIAMETER

AT THE ENDIn.

CONSTRUCTION

MIL-W-87161MINIMUMBREAK

STRENGTHCOMP A & B

Lbs.IIIIIIIIIIIIIIIIIIIIIIIIIII

1/323/643/641/161/165/643/327/641/85/323/167/321/45/163/8

0.0030.0050.0050.0060.0060.0080.0090.0090.0130.0130.0130.0150.0180.0220.026

0.0060.0080.0080.0090.0090.0090.0100.0100.0110.0160.0190.0200.0210.0240.027

1 x 71 x 71 x 191 x 71 x 191 x 191 x 191 x 191 x 191 x 191 x 191 x 191 x 191 x 191 x 19

185375375500500800

1,2001,6002,1003,3004,7006,3008,200

12,50017,500

FIGURE 7-9. Nonflexible cable cross section.

wires laid around a center wire in a counter-clockwise direction. The 1 by 19 cable con-sists of a layer of six wires laid around a centerwire in a clockwise direction plus twelve wireslaid around the inner strand in a counterclock-wise direction.

7-145. CABLE SPECIFICATIONS. Cablediameter and strength data are given in ta-ble 7-3 and table 7-4. These values are accept-able for repair and modification of civil air-craft.

7-146. CABLE PROOF LOADS. Cableterminals and splices should be tested forproper strength before installation. Graduallyapply a test load equal to 60 percent of the ca-ble-breaking strengths given in table 7-3 and

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table 7-4, for a period of 3 minutes. Place asuitable guard over the cable during the test toprevent injury to personnel in the event of ca-ble failure.

7-147. REPLACEMENT OF CABLES.Replace control cables when they becomeworn, distorted, corroded, or otherwise dam-aged. If spare cables are not available, prepareexact duplicates of the damaged cable. Usematerials of the same size and quality as theoriginal. Standard swaged cable terminals de-velop the full cable strength and may be sub-stituted for the original terminals whereverpractical. However, if facilities and suppliesare limited and immediate corrective action isnecessary, repairs may be made by using cablebushings, eye splices, and the proper combina-tion of turnbuckles in place of the original in-stallation. (See figure 7-12(c).)

a. Location of Splices. Locate splices sothat no portion of the splice comes closer than2 inches to any fair-lead or pulley. Locateconnections at points where jamming cannotoccur during any portion of the travel of eitherthe loaded cable or the slack cable in the de-flected position.

b. Cutting and Heating. Cut cables tolength by mechanical means. The use of atorch, in any manner, is not permitted. Do notsubject wires and cables to excessive tem-perature. Soldering the bonding braid to thecontrol cable is not permitted.

c. Ball-and-Socket Type Terminals. Donot use ball-and-socket type terminals or othertypes for general replacement that do not posi-tively prevent cable untwisting, except wherethey were utilized on the original installationby the aircraft manufacturer.

d. Substitution of Cable. Substitution ofcable for hard or streamlined wires will not be

acceptable unless specifically approved by arepresentative of the FAA.

7-148. MECHANICALLY-FABRI-CATED CABLE ASSEMBLIES.

a. Swage-Type Terminals. Swage-typeterminals, manufactured in accordance withAN, are suitable for use in civil aircraft up to,and including, maximum cable loads. Whenswaging tools are used, it is important that allthe manufacturers’ instructions, including “goand no-go” dimensions, be followed in detailto avoid defective and inferior swaging. Ob-servance of all instructions should result in aterminal developing the full-rated strength ofthe cable. Critical dimensions, both before andafter swaging, are shown in table 7-5.

(1) Terminals. When swaging terminalsonto cable ends, observe the following proce-dures.

(a) Cut the cable to the proper lengthallowing for growth during swaging. Apply apreservative compound to the cable ends be-fore insertion into the terminal barrel.

NOTE: Never solder cable ends toprevent fraying, since the presence ofthe solder will greatly increase the ten-dency of the cable to pull out of theterminal.

(b) Insert the cable into the terminalapproximately 1 inch, and bend toward theterminal, then push the cable end entirely intothe terminal barrel. The bending action puts akink or bend in the cable end, and providesenough friction to hold the terminal in placeuntil the swaging operation can be performed.Bending also tends to separate the strands in-side the barrel, thereby reducing the strain onthem.

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Par 7-148 Page 7-31

TABLE 7-5. Straight-shank terminal dimensions. (Cross reference AN to MS: AN-666 to MS 21259, AN-667 toMS 20667, AN-668 to MS 20668, AN-669 to MS 21260.)

Before swaging After swaging

Cable size(inches)

Wire strands Outsidediameter

Borediameter

Borelength

Swaginglength

Minimumbreakingstrength(pounds)

Shankdiameter

*1/163/321/85/323/167/321/49/325/163/8

7 x 77 x 7

7 x 197 x 197 x 197 x 197 x 197 x 197 x 197 x 19

0.160.218.250.297.359.427.494.563.635.703

0.078.109.141.172.203.234.265.297.328.390

1.0421.2611.5111.7612.0112.2612.5112.7613.0113.510

0.9691.1881.4381.6881.9382.1882.4382.6882.9383.438

480920

2,0002,8004,2005,6007,0008,0009,800

14,400

0.138.190.219.250.313.375.438.500.563.625

*Use gauges in kit for checking diameters.

NOTE: If the terminal is drilled com-pletely through, push the cable into theterminal until it reaches the approxi-mate position shown in figure 7-10. Ifthe hole is not drilled through, insertthe cable until the end rests against thebottom of the hole.

FIGURE 7-10. Insertion of cable into terminal.

(c) Accomplish the swaging opera-tion in accordance with the instructions fur-nished by the manufacturer of the swagingequipment.

(d) Inspect the terminal after swagingto determine that it is free from the die marksand splits, and is not out-of-round. Check for

cable slippage in the terminal and for cut orbroken wire strands.

(e) Using a “go no-go” gauge or amicrometer, check the terminal shank diameteras shown in figure 7-11 and table 7-5.

FIGURE 7-11. Gauging terminal shank after swaging.

(f) Test the cable by proof-loading itto 60 percent of its rated breaking strength.

(2) Splicing. Completely severed ca-bles, or those badly damaged in a localizedarea, may be repaired by the use of an eye

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terminal bolted to a clevis terminal. (See fig-ure 7-12(a).) However, this type of splice canonly be used in free lengths of cable which donot pass over pulleys or through fair-leads.

FIGURE 7-12. Typical cable splices.

(3) Swaged ball terminals. On someaircraft cables, swaged ball terminals are usedfor attaching cables to quadrants and specialconnections where space is limited. Singleshank terminals are generally used at the cableends, and double shank fittings may be used ateither the end or in the center of the cable.Dies are supplied with the swaging machinesfor attaching these terminals to cables by thefollowing method.

(a) The steel balls and shanks have ahole through the center, and are slipped overthe cable and positioned in the desired loca-tion.

(b) Perform the swaging operation inaccordance with the instructions furnished bythe manufacturer of the swaging equipment.

(c) Check the swaged fitting with a“go no-go” gauge to see that the fitting isproperly compressed, and inspect the physicalcondition of the finished terminal. (See fig-ure 7-13.)

FIGURE 7-13. Typical terminal gauge.

(4) Cable slippage in terminal. Ensurethat the cable is properly inserted in the termi-nal after the swaging operation is completed.Instances have been noted wherein only1/4 inch of the cable was swaged in the termi-nal. Observance of the following precautionsshould minimize this possibility.

(a) Measure the length of the termi-nal end of the fitting to determine the properlength of cable to be inserted into the barrel ofthe fitting.

(b) Lay off this length at the end ofthe cable and mark with masking tape. Sincethe tape will not slip, it will provide a positivemarking during the swaging process.

(c) After swaging, check the tapemarker to make certain that the cable did notslip during the swaging operation.

(d) Remove the tape and paint thejunction of the swaged fitting and cable withred tape.

(e) At all subsequent service inspec-tions of the swaged fitting, check for a gap inthe painted section to see if cable slippage hasoccurred.

b. Nicopress Process. A patented processusing copper sleeves may be used up to the fullrated strength of the cable when the cable islooped around a thimble. This process mayalso be used in place of the five-tuck splice on

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Par 7-148 Page 7-33

cables up to and including 3/8 inch diameter.The use of sleeves that are fabricated of mate-rials other than copper will require engineeringapproval for the specific application by theFAA.

(1) Before undertaking a nicopresssplice, determine the proper tool and sleeve forthe cable to be used. Refer to table 7-6 and ta-ble 7-7 for details on sleeves, tools, and thenumber of presses required for the varioussizes of aircraft cable. The tool must be ingood working condition and properly adjustedto ensure a satisfactory splice.

(2) To compress a sleeve, have it well-centered in the tool groove with the major axisof the sleeve at right angles to the tool. If thesleeve appears to be out of line after the pressis started, open the tool, re-center the sleeve,and complete the press.

c. Thimble-Eye Splice. Before under-taking a thimble-eye splice, initially positionthe cable so the end will extend slightly be-yond the sleeve, as the sleeve will elongatesomewhat when it is compressed. If the cableend is inside the sleeve, the splice may nothold the full strength of the cable. It is desir-able that the oval sleeve be placed in closeproximity to the thimble points, so that whencompressed, the sleeve will contact the thimbleas shown in figure 7-14. The sharp ends of thethimble may be cut off before being used;however, make certain the thimble is firmlysecured in the cable loop after the splice hasbeen completed. When using a sleeve requir-ing three compressions, make the center com-pression first, the compression next to thethimble second, and the one farthest from thethimble last.

d. Lap Splice. Lap or running splicesmay also be made with copper oval sleeves.When making such splices, it is usually neces-sary to use two sleeves to develop the full

FIGURE 7-14. Typical thimble-eye splice.

strength of the cable. The sleeves should bepositioned as shown in figure 7-12(b), and thecompressions made in the order shown. As inthe case of eye splices, it is desirable to havethe cable ends extend beyond the sleeves suffi-ciently to allow for the increased length of thecompressed sleeves.

e. Stop Sleeves. Stop sleeves may be usedfor special cable end and intermediate fittings.They are installed in the same manner as nico-press oval sleeves.

NOTE: All stop sleeves are plain cop-per. Certain sizes are colored for iden-tification.

f. Terminal Gauge. To make a satisfac-tory copper sleeve installation, it is importantthat the amount of sleeve pressure be kept uni-form. The completed sleeves should bechecked periodically with the proper gauge.Hold the gauge so that it contacts the majoraxis of the sleeve. The compressed portion atthe center of the sleeve should enter the gaugeopening with very little clearance, as shown infigure 7-15. If it does not, the tool must beadjusted accordingly.

g. Other Applications. The preceding in-formation regarding copper oval sleeves andstop sleeves is based on tests made with flexi-ble aircraft cable. The sleeves may also be

AC 43.13-1B 9/8/98

Page 7-34 Par 7-148

TABLE 7-6. Copper oval sleeve data.

Copper oval sleeve stock No.

Cable size Plain Plated* Manual toolNo.

Sleeve lengthbefore com-pression (ap-

prox.)(inches)

Sleeve lengthafter com-

pression (ap-prox.)

(inches)

Number ofpresses

Testedstrength(pounds)

3/64 18-11-B4 28-11-B4 51-B4-887 3/8 7/16 1 3401/16 18-1-C 28-1-C 51-C-887 3/8 7/16 1 5503/32 18-2-G 28-2-G 51-G-887 7/16 1/2 1 1,1801/8 18-3-M 28-3-M 51-M-850 9/16 3/4 3 2,3005/32 18-4-P 28-4-P 51-P-850 5/8 7/8 3 3,0503/16 18-6-X 28-6-X 51-X-850 1 1 1/4 4 4,3507/32 18-8-F2 28-8-F2 51-F2-850 7/8 1 1/16 4 5,7901/4 18-10-F6 28-10-F6 3-F6-950 1 1/8 1 1/2 3 7,1805/16 18-13-G9 28-13-G9 3-G9-950 1 1/4 1 5/8 3 11,130

No. 635Hydraulic tool

dies3/8 18-23-H5 28-23-H5 Oval H5 1 1/2 1 7/8 1 16,8007/16 18-24-J8 28-24-J8 Oval J8 1 3/4 2 1/8 2 19,7001/2 18-25-K8 28-25-K8 Oval K8 1 7/8 2 1/2 2 25,2009/16 18-27-M1 28-27-M1 Oval M1 2 2 5/8 3 31,0255/8 18-28-N5 28-28-N5 Oval N5 2 3/8 3 1/8 3 39,200*Required on stainless cables due to electrolysis caused by different types of metals.

TABLE 7-7. Copper stop sleeve data.

Cable size (inch) Sleeve No. Tool No. Sleeve Sleeve Tested strength (pounds)3/64 871-12-B4 51-B4-887 7/32 11/64 2801/16 871-1-C 51-C-887 7/32 13/64 5253/32 871-17-J

(Yellow)51-MJ 5/16 21/64 600

1/8 S71-18-J(Red)

51-MJ 5/16 21/64 800

5/32 871-19-M 51-MJ 5/16 27/64 1,2003/16 871-20-M

(Black)51-MJ 5/16 27/64 1,600

7/32 871-22-M 51-MJ 5/8 7/16 2,3001/4 871-23-F6 3-F6-950 11/16 21/32 3,5005/16 871-26-F6 3-F6-950 11/16 21/32 3,800

NOTE: All stop sleeves are plain copper. Certain sizes are colored for identification.

used on wire ropes of other construction, ifeach specific type of cable is proof-tested ini-tially. Because of variation in rope strengths,grades, construction, and actual diameters, thetest is necessary to insure proper selection ofmaterials, the correct pressing procedure, andan adequate margin of safety for the intendeduse. FIGURE 7-15. Typical terminal gauge.

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Par 7-149 Page 7-35

7-149. CABLE SYSTEM INSPECTION.Aircraft cable systems are subject to a varietyof environmental conditions and deterioration.Wire or strand breakage is easy to visually rec-ognize. Other kinds of deterioration such aswear, corrosion, and/or distortion are not easilyseen; therefore, control cables should be re-moved periodically for a more detailed inspec-tion.

a. At each annual or 100 hour inspec-tion, all control cables must be inspected forbroken wires strands. Any cable assembly thathas one broken wire strand located in a criticalfatigue area must be replaced.

b. A critical fatigue area is defined as theworking length of a cable where the cable runsover, under, or around a pulley, sleeve, orthrough a fair-lead; or any section where thecable is flexed, rubbed, or worked in any man-ner; or any point within 1 foot of a swaged-onfitting.

c. A swaged-on fitting can be an eye,fork, ball, ball and shank, ball and doubleshank, threaded stud, threaded stud and turn-buckle, compression sleeve, or any hardwareused as a termination or end fitting on the ca-ble. These fittings may be attached by variousswaging methods such as rotary swaging, rollswaging, hydraulic pressing, and hand swagingtools. (See MIL-T-781.) The pressures ex-erted on the fittings during the swaging proc-ess sometimes pinch the small wires in the ca-ble. This can cause premature failure of thepinched wires, resulting in broken wires.

d. Close inspection in these critical fa-tigue areas, must be made by passing a clothover the area to snag on broken wires. Thiswill clean the cable for a visual inspection, anddetect broken wires if the cloth snags on thecable. Also, a very careful visual inspection

must be made since a broken wire will not al-ways protrude or stick out, but may lie in thestrand and remain in the position of the helixas it was manufactured. Broken wires of thistype may show up as a hairline crack in thewire. If a broken wire of this type is sus-pected, further inspection with a magnifyingglass of 7 power or greater, is recommended.Figure 7-16 shows a cable with broken wiresthat was not detected by wiping, but was foundduring a visual inspection. The damage be-came readily apparent when the cable was re-moved and bent as shown in figure 7-16.

FIGURE 7-16. Cable inspection technique.

e. Kinking of wire cable can be avoidedif properly handled and installed. Kinking iscaused by the cable taking a spiral shape as theresult of unnatural twist. One of the mostcommon causes for this twist is improper un-reeling and uncoiling. In a kinked cable,strands and wires are out of position, whichcreates unequal tension and brings excessivewear at this part of the cable. Even though thekink may be straightened so that the damageappears to be slight, the relative adjustmentbetween the strands has been disturbed so thatthe cable cannot give maximum service andshould be replaced. Inspect cables for apopped core or loose strands. Replace any ca-ble that has a popped core or loose strands re-gardless of wear or broken wires.

AC 43.13-1B CHG 1 9/27/01

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f. Nylon-jacketed cable with any cracksor necking down in the diameter of the jacketshall be replaced. Usable cable life is overwhen these conditions begin to appear in thenylon jacket.

g. External wear patterns will extendalong the cable equal to the distance the cablemoves at that location and may occur on oneside of the cable or on its entire circumference.Replace flexible and nonflexible cables whenthe individual wires in each strand appear toblend together (outer wires worn 40 to 50 per-cent) as depicted in figure 7-17. Actual in-stances of cable wear beyond the recom-mended replacement point are shown in fig-ure 7-18.

FIGURE 7-17. Cable wear patterns.

h. As wear is taking place on the exteriorsurface of a cable, the same condition is takingplace internally, particularly in the sections ofthe cable which pass over pulleys and quad-rants. This condition (shown in figure 7-19) isnot easily detected unless the strands of the ca-ble are separated. This type of wear is a resultof the relative motion between inner wire sur-faces. Under certain conditions, the rate of thistype of wear can be greater than that occurringon the surface.

FIGURE 7-18. Worn cable (replacement necessary).

i. Areas especially conducive to cablecorrosion are battery compartments, lavatories,wheel wells, etc.; where a concentration ofcorrosive fumes, vapors, and liquids can ac-cumulate. Carefully examine any cable forcorrosion, when it has a broken wire in a sec-tion that is not in contact with a wear-producing airframe component, such as a pul-ley, fair-lead, etc. If the surface of the cable iscorroded, relieve cable tension and carefullyforce the cable open by reverse twisting andvisually inspect the interior. Corrosion on theinterior strands of the cable constitutes failure,and the cable must be replaced. If no internalcorrosion is detected, remove loose externalrust and corrosion with a clean, dry, coarse-weave rag, or fiber brush. Do not use metallic

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Par 7-149 Page 7-37

FIGURE 7-19. Internal end view of cable wear.

wool or solvents to clean installed cables. Useof metallic wool will embed dissimilar metalparticles in the cables and create further corro-sion problems. Solvents will remove internalcable lubricant allowing cable strands toabrade and further corrode. After thoroughcleaning, sparingly apply specificationMIL-C-16173, grade 4, corrosion-preventivecompound to cable. Do not apply the materialso thick that it will interfere with the operationof cables at fair-leads, pulleys, or groovedbellcrank areas.

j. Examine cable runs for incorrect rout-ing, fraying, twisting, or wear at fair-leads,pulleys, antiabrasion strips, and guards. Lookfor interference with adjacent structure,equipment, wiring, plumbing, and other con-trols. Inspect cable systems for binding, fulltravel, and security of attaching hardware.Check for slack in the cable system by at-tempting to move the control column and/orpedals while the gust locks are installed on thecontrol surfaces. With the gust locks removed,

actuate the controls and check for friction orhard movement. These are indications that ex-cessive cable tension exists.

NOTE: If the control movement is stiffafter maintenance is performed on con-trol surfaces, check for parallel cablestwisted around each other, or cablesconnected in reverse.

k. Check swaged terminal referencemarks for an indication of cable slippagewithin the fitting. Inspect the fitting assemblyfor distortion and/or broken strands at the ter-minal. Ensure that all bearings and swivel fit-tings (bolted or pinned) pivot freely to preventbinding and subsequent failure. Check turn-buckles for proper thread exposure and brokenor missing safety wires/clips.

l. Inspect pulleys for roughness, sharpedges, and presence of foreign material em-bedded in the grooves. Examine pulley bear-ings to ensure proper lubrication, smooth rota-tion; and freedom from flat spots, dirt, andpaint spray. During the inspection, rotate thepulleys, which only turn through a small arc, toprovide a new bearing surface for the cable.Maintain pulley alignment to prevent the cablefrom riding on the flanges and chafing againstguards, covers, or adjacent structure. Checkall pulley brackets and guards for damage,alignment, and security.

m. Various cable system malfunctionsmay be detected by analyzing pulley condi-tions. These include such discrepancies as toomuch tension, misalignment, pulley bearingproblems, and size mismatches between cablesand pulleys. Examples of these condition areshown in figure 7-20.

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FIGURE 7-20. Pulley wear patterns.

n. Inspect fair-leads for wear, breakage,alignment, cleanliness, and security. Examinecable routing at fair-leads to ensure that defec-tion angles are no greater than 3°€maximum.Determine that all guides and anti-abrasionstrips are secure and in good condition.

o. Examine pressure seals for wear and/ormaterial deterioration. Seal guards should bepositioned to prevent jamming of a pulley incase pressure seal fails and pieces slide alongthe cable.

7-150. CORROSION AND RUST PRE-VENTION. To ensure a satisfactory servicelife for aircraft control cables, use a cable lu-bricant to reduce internal friction and preventcorrosion.

a. If the cable is made from tinned steel,coat the cable with rust-preventive oil, and

wipe off any excess. It should be noted thatcorrosion-resistant steel cable does not requirethis treatment for rust prevention.

b. Lubrication and corrosion preventivetreatment of carbon steel cables may be ef-fected simultaneously by application of com-pound MIL-C-16173, grade 4, orMIL-C-11796, Class I. MIL-C-16173 com-pound should be brushed, sprayed, or wiped onthe cable to the extent it penetrates into thestrands and adequately covers the cable sur-faces. It will dry “tack free” in 24 hours at77 °F. MIL-C-11796 compound is applied bydipping the cable for 1/2 minute into a tank ofcompound heated to 77 ° ± 5 °C (170 ° ± 9 °F)for 1/2 minute then removing it and wiping offthe excess oil. (An example of cable corro-sion, attributable to battery acid, is shown infigure 7-21.)

9/27/01 AC 43.13-1B CHG 1

Par 7-151 Page 7-39 (and 7-40)

FIGURE 7-21. Corrosion.

7-151. WIRE SPLICES. Standard manu-facturing splices have been mistaken for de-fects in the cable because individual wire endsplices were visible after assembly of a fin-ished cable length. In some instances, the pro-cess of twisting outer strands around the corestrand may also slightly flatten individual outerwires, particularly in the area of a wire splice.This flattening is the result of die-sizing thecable, and does not affect the strength of thecable. These conditions (as shown in fig-ure 7-22) are normal, and are not a cause forcable rejection.

FIGURE 7-22. Manufacturer’s wire splice.

7-152. CABLE MAINTENANCE. Fre-quent inspections and preservation measuressuch as rust-prevention treatments for barecarbon steel cable areas, will help to extendcable service life. Where cables pass throughfair-leads, pressure seals, or over pulleys, re-move accumulated heavy coatings of corro-sion-prevention compound. Provide corrosionprotection for these cable sections by lubricat-ing with a light coat of grease or general-purpose, low-temperature oil.

7-153. CABLE TENSION ADJUST-MENT. Carefully adjust, control cable tensionin accordance with the airframe manufacturer’srecommendations. On large aircraft, take thetemperature of the immediate area into consid-eration when using a tension meter. For longcable sections, use the average of two or threetemperature readings to obtain accurate tensionvalues. If necessary, compensate for extremesurface temperature variations that may be en-countered if the aircraft is operated primarilyin unusual geographic or climatic conditionssuch as arctic, arid, or tropic locations. Userigging pins and gust locks, as necessary, to en-sure satisfactory results. At the completion ofrigging operations, check turnbuckle adjustmentand safetying in accordance with section 10 ofthis chapter.

7-154. 7-164. [RESERVED.]