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Rotorcraft and Gyroplane Wiki - Sharepoint > GyroWiki > aircraft hardware, control cables, and turn buckles  

aircraft hardware, control cables, and turn buckles

 
 
9/8/98
AC 43.13-1B
chapter 7. aircraft hardware, control cables,
and turnbuckles
SECTION 1. RIVETS
7-1. GENERAL.
a. Standard solid-shank rivets and the
universal head rivets (AN470) are used in air­craft construction in both interior and exterior locations. All protruding head rivets may be replaced by MS20470 (supersedes AN470) rivets. This has been adopted as the standard for protruding head rivets in the United States.
b. Roundhead rivets (AN430) are used in the interior of aircraft except where clearance is required for adjacent members.
c. Flathead rivets (AN442) are used in the interior of the aircraft where interference of adjacent members does not permit the use of roundhead rivets.
d. Brazierhead rivets (AN455 and AN456) are used on the exterior surfaces of aircraft where flush riveting is not essential.
e. Countersunk head rivets MS20426
(supersedes AN426 100-degree) are used on the exterior surfaces of aircraft to provide a smooth aerodynamic surface, and in other ap­plications where a smooth finish is desired. The 100-degree countersunk head has been adopted as the standard in the United States. Refer to MIL-HD BK5 Metallic Materials and Elements for Fight Vehicle Structures, and U.S.A.F./Navy T./O. 1-1A-8, Structural Hard­ware."
f. Typical rivet types are shown in ta­ble 7-10.
7-2. MATERIAL APPLICATIONS.
a. Rivets made with 2117-T4 are the
most commonly used rivets in aluminum alloy structures. The main advantage of 2117-T4 is that it may be used in the condition received without further treatment.
b. The 2017-T3, 2017-T31, and 2024-T4
rivets are used in aluminum alloy structures where strength higher than that of the 2117-T4 rivet is needed. See Metallic Materials and Elements for Flight Vehicle Structures (MIL-HDBK-5) for differences between the types of rivets specified here.
c. The 1100 rivets of pure aluminum are
used for riveting nonstructural parts fabricated from the softer aluminum alloys, such as 1100, 3003, and 5052.
d. When riveting magnesium alloy structures, 5056 rivets are used exclusively due to their corrosion-resistant qualities in combination with the magnesium alloys.
e. Mild steel rivets are used primarily in riveting steel parts. Do not use galvanized rivets on steel parts subjected to high heat.
f. Corrosion-resistant steel rivets are
used primarily in riveting corrosion-resistant steel parts such as firewalls, exhaust stack bracket attachments, and similar structures.
Par 7-1
Page 7-1
AC 43.13-1B CHG 1
9/27/01
g. Monel rivets are used in special cases for riveting high-nickel steel alloys and nickel alloys. They may be used interchangeably with stainless steel rivets as they are more eas­ily driven. However, it is preferable to use stainless steel rivets in stainless steel parts.
h. Copper rivets are used for riveting copper alloys, leather, and other nonmetallic materials. This rivet has only limited usage in aircraft.
i. Hi-Shear rivets are sometimes used in connections where the shearing loads are the primary design consideration. Its use is re­stricted to such connections. It should be noted that Hi-Shear rivets are not to be used for the installation of control surface hinges and hinge brackets. Do not paint the rivets be­fore assembly, even where dissimilar metals are being joined. However, it is advisable to touch up each end of the driven rivet with primer to allow the later application of the general airplane finish.
j. Blind rivets in the NASM20600 I through NASM20603 series rivets and the me­chanically-locked stem NAS 1398, 1399, 1738, and 1739 rivets sometimes may be sub­stituted for solid rivets. They should not be used where the looseness or failure of a few rivets will impair the airworthiness of the air­craft. Design allowable for blind rivets are specified in MIL-HDBK-5. Specific structural applications are outlined in NASM33522. Nonstructural applications for such blind rivets
as NASM20604 and NASM20605 are con­tained in NASM33557.
CAUTION: For sheet metal repairs to air­frame, the use of blind rivets must be authorized by the airframe manufacturer or approved by a representative of the FAA.
For more information on blind rivets, see page 4-19, f. of this document.
7-3.—7-13. [RESERVED.]
Page 7-2
Par 7-2
9/8/98
AC 43.13-1B
SECTION 2. SCREWS
7-14. GENERAL. In general, screws differ from bolts by the following characteristics.
a. Screws usually have lower material strength, a looser thread fit, head shapes formed to engage a screwdriver, and the shank may be threaded along its entire length without a clearly defined grip. Screws may be divided into three basic groups: structural screws, ma­chine screws, and self-tapping screws. Screws are marked as required by the applicable Army Navy (AN), National Aerospace Standard (NAS), or Military Standard (MS) drawing. Normally a manufacturer places his trademark on the head of the screw. Several types of structural screws are available that differ from the standard structural bolts only in the type of head.
b. It would be impossible to cover all
screws that are available to the aviation mar­ket; therefore, only the most frequently used screws will be discussed in this text. Design specifications are available in MIL-HDBK-5, or U.S.A.F./Navy T.O.1-1A-8/NAVAIR 01-1A-8, Structural Hardware.
c. Typical screw types are shown in ta­ble 7-11.
7-15. STRUCTURAL SCREWS. NAS502, NAS503, AN509, NAS220 through NAS227,
and NAS583 through NAS590, may be used
for structural applications, similar to structural bolts or rivets. These screws are fabricated from a material with a high-tensile strength and differ from structural bolts only in the type of head.
7-16. MACHINE SCREWS. These screws are available in four basic head styles: flat-head (countersunk), roundhead, fillister, and socket head.
a. Flathead machine screws (AN505, AN510, AN507, NAS200, NAS514, NAS517, and NAS662) are used in countersunk holes where a flush surface is desired.
b. Roundhead machine screws (AN515 and AN520) are general-purpose screws for use in nonstructural applications.
c. Fillister head machine screws (AN500 through AN503, AN116901 through
AN116912, AN116913 through AN116924, AN116962 through AN116990, AN117002 through AN117030, and AN117042 through
AN117070) are general-purpose screws that may be used as capscrews in light mechanical applications and are usually drilled for safety wire.
d. Socket head machine screws
(NAS608 and NAS609) are designed to be
driven into tapped holes by means of internal wrenches. They may be used in applications requiring high strength, compactness of as­sembled parts, or sinking of heads below sur­faces into fitted holes.
7-17. PANHEAD SCREWS (NAS600 THROUGH NAS606, NAS610 THROUGH NAS616, NAS623, AND NAS1402
THROUGH NAS1406). Flathead screws (MS35188 through MS35203), panhead ma­chine screws (MS35024 through MS35219),
and truss-head screws (AN526) are general-purpose screws used where head height is not important.
7-18. SELF-TAPPING SCREWS. The
self-tapping screw taps their own mating thread when driven into untapped or punched holes slightly smaller than the diameter of the screw. Self-tapping machine screws (AN504 and AN530), may be used to attach minor
Par 7-14
Page 7-3
AC 43.13-1B
9/8/98
nonstructural parts. Self-tapping sheet metal
screws (AN504, AN530, AN531 and NAS548)
may be used in blind applications for the tem­porary attachment of sheet metal for riveting and the permanent assembly of nonstructural assemblies. The MS21318 is a roundhead drive screw used in the attachment of name-plates or in sealing drain holes, and is not in­tended to be removed after installation. They are normally installed by driving the screw into a drilled hole with a hammer.
CAUTION: Self-tapping screws should never be used as a replacement for standard screws, nuts, bolts, or rivets in any aircraft structure.
7-19. WOOD SCREWS AN545 and
AN550, MS35492 and MS35493 are screws
used in wood structures of aircraft.
7-20.—7-33. [RESERVED.]
Page 7-4
Par 7-18
9/8/98
AC 43.13-1B
SECTION 3. BOLTS
7-34. GENERAL. "Hardware" is the term used to describe the various types of fasteners and small items used to assemble and repair aircraft structures and components. Only hardware with traceability to an approved manufacturing process or source should be used. This traceability will ensure that the hardware is at least equal to the original or properly-altered condition. Hardware that is not traceable or is improperly altered, may be substandard or counterfeit, since their physical properties cannot be substantiated. Selection and use of fasteners are as varied as the types of aircraft; therefore, care should be taken to ensure fasteners are approved by the Federal Aviation Administration (FAA) for the in­tended installation, repair, or replacement. Threaded fasteners (bolts/screws) and rivets are the most commonly used fasteners because they are designed to carry shear and/or tensile loads.
7-35. BOLTS. Most bolts used in aircraft structures are either general-purpose, internal-wrenching, or close-tolerance AN, NAS, or MS bolts. In certain cases, fastener manufac­turers produce bolts of different dimensions or greater strength than the standard types. Such bolts are made for a particular application, and it is of extreme importance to use like bolts in replacement. Design specifications are available in MIL-HDBK-5 or USAF/Navy T.O. 1-1A-8/NAVAIR 01-1A-8. References should be made to military specifications and industry design standards such as NAS, the Society of Automotive Engineers (SAE), and Aerospace Material Standards (AMS). Typical bolt types are shown in table 7-12.
7-36. IDENTIFICATION. Aircraft bolts may be identified by code markings on the bolt heads. These markings generally denote the material of which the bolt is made, whether the
bolt is a standard AN-type or a special-purpose bolt, and sometimes include the manufacturer.
a. AN standard steel bolts are marked with either a raised dash or asterisk, corrosion-resistant steel is marked by a single dash, and AN aluminum-alloy bolts are marked with two raised dashes.
b. Special-purpose bolts include high-strength, low-strength, and close-tolerance types. These bolts are normally inspected by magnetic particle inspection methods. Typical markings include "SPEC" (usually heat-treated for strength and durability), and an aircraft manufacturer's part number stamped on the head. Bolts with no markings are low strength. Close-tolerance NAS bolts are marked with either a raised or recessed triangle. The mate­rial markings for NAS bolts are the same as for AN bolts, except they may be either raised or recessed. Bolts requiring non-destructive in­spection (NDI) by magnetic particle inspection are identified by means of colored lacquer, or head markings of a distinctive type. (See fig­ure 7-1.)
7-37. GRIP LENGTH. In general, bolt grip lengths of a fastener is the thickness of the material the fastener is designed to hold when two or more parts are being assembled. Bolts of slightly greater grip length may be used, provided washers are placed under the nut or bolthead. The maximum combined height of washers that should be used is 1/8 inch. This limits the use of washers necessary to compen­sate for grip, up to the next standard grip size. Over the years, some fasteners specifications have been changed. For this reason, it is rec­ommended when making repairs to an aircraft, whose original hardware is being replaced, that you must first measure the bolt before order­ing, rather than relying on the parts manual for
Par 7-34
Page 7-5
AC 43.13-1B
9/8/98
of 0.0006 inch for a 5/8 inch bolt. Bolt holes should be flush to the surface, and free of de­bris to provide full bearing surface for the bolt head and nut. In the event of over-sized or elongated holes in structural members, ream­ing or drilling the hole to accept the next larger bolt size may be permissible. Care should be taken to ensure items, such as edge distance, clearance, and structural integrity are main­tained. Consult the manufacturer's structural repair manual, the manufacturer's engineering department, or the FAA before drilling or reaming any bolt hole in a critical structural member.
7-40. TORQUES. The importance of cor­rect torque application cannot be overempha­sized. Undertorque can result in unnecessary wear of nuts and bolts, as well as the parts they secure. Overtorque can cause failure of a bolt or nut from overstressing the threaded areas. Uneven or additional loads that are applied to the assembly may result in wear or premature failure. The following are a few simple, but important procedures, that should be followed to ensure that correct torque is applied.
NOTE: Be sure that the torque ap­plied is for the size of the bolt shank
not the wrench size.
a. Calibrate the torque wrench at least once a year, or immediately after it has been abused or dropped, to ensure continued accu­racy.
b. Be sure the bolt and nut threads are clean and dry, unless otherwise specified by the manufacturer.
c. Run the nut down to near contact
with the washer or bearing surface and check the friction drag torque required to turn the nut. Whenever possible, apply the torque to the nut and not the bolt. This will reduce rota­tion of the bolt in the hole and reduce wear.
Figure 7-1. Typical aircraft bolt markings.
identification. In the case of plate nuts, if proper bolt grip length is not available, add shims under the plate. All bolt installations which involve self-locking or plain nuts should have at least one thread of the bolt protruding through the nut.
7-38. LOCKING OR SAFETYING OF BOLTS. Lock or safety all bolts and/or nuts, except self-locking nuts. Do not reuse cotter pins or safety wire.
7-39. BOLT FIT. Bolt holes, particularly those of primary connecting elements, have close tolerances. Generally, it is permissible to use the first-lettered drill size larger than the nominal bolt diameter, except when the AN hexagon bolts are used in light-drive fit (reamed) applications and where NAS close-tolerance bolts or AN clevis bolts are used. A light-drive fit can be defined as an interference
Page 7-6
Par 7-37
9/8/98
AC 43.13-1B
d. Add the friction drag torque to the
desired torque. This is referred to as "final torque," which should register on the indicator or setting for a snap-over type torque wrench.
e. Apply a smooth even pull when ap­plying torque pressure. If chattering or a jerk­ing motion occurs during final torque, back off the nut and retorque.
NOTE: Many applications of bolts in aircraft/engines require stretch checks prior to reuse. This requirement is due primarily to bolt stretching caused by overtorquing.
f. When installing a castle nut, start alignment with the cotter pin hole at the mini­mum recommended torque plus friction drag torque.
NOTE: Do not exceed the maximum torque plus the friction drag. If the hole and nut castellation do not align, change washer or nut and try again. Exceeding the maximum recom­mended torque is not recommended.
g. When torque is applied to bolt heads or capscrews, apply the recommended torque plus friction drag torque.
h. If special adapters are used which will change the effective length of the torque wrench, the final torque indication or wrench setting must be adjusted accordingly. Deter­mine the torque wrench indication or setting with adapter installed as shown in figure 7-2.
i. Table 7-1 shows the recommended torque to be used when specific torque is not supplied by the manufacturer. The table in­cludes standard nut and bolt combinations, currently used in aviation maintenance. For further identification of hardware, see chap­ter 7, section 11.
7-41. STANDARD AIRCRAFT HEX
HEAD BOLTS (AN3 THROUGH AN20).
These are all-purpose structural bolts used for general applications that require tension or shear loads. Steel bolts smaller than No. 10-32, and aluminum alloy bolts smaller than 1/4 inch diameter, should not be used in primary structures. Do not use aluminum bolts or nuts in applications requiring frequent re­moval for inspection or maintenance.
7-42. DRILLED HEAD BOLTS (AN73 THROUGH AN81). The AN drilled head
bolt is similar to the standard hex bolt, but has a deeper head which is drilled to receive safety wire. The physical differences preventing di­rect interchangeability are the slightly greater head height, and longer thread length of the
AN73 through AN81 series. The AN73
through AN81 drilled head bolts have been su­perseded by MS20073, for fine thread bolts and MS20074 for coarse thread bolts. AN73, AN74, MS20073, and MS20074 bolts of like
thread and grip lengths are universally, func­tionally, and dimensionally interchangeable.
7-43. ENGINE BOLTS. These are hex
head bolts (AN101001 through AN101900), drilled shank hex head bolts (AN101901
through AN102800), drilled hex head (one
hole) bolts (AN102801 through AN103700), and drilled hex head (six holes) bolts
(AN103701 through AN104600). They are
similar to each other except for the holes in the head and shank. Hex head bolts (AN104601 through AN105500), drilled shank hex head bolts (AN105501 through AN106400), drilled hex head (one hole) bolts (AN106401 through AN107300), and drilled hex head (six holes)
bolts (AN107301 through AN108200) are similar to the bolts described in para­graph 7-42, except that this series is manufac­tured from corrosion-resistant steel.
Par 7-40
Page 7-7
AC 43.13-1B
9/8/98
Figure 7-2. Torque wrench with various adapters.
Page 7-8
Par 7-43
9/8/98
AC 43.13-1B
Table 7-1. Recommended torque values (inch-pounds).
CAUTION
THE FOLLOWING TORQUE VALUES ARE DERIVED FROM OIL FREE CADMIUM PLATED THREADS.
TORQUE LIMITS RECOMMENDED FOR INSTAL­LATION (BOLTS LOADED PRIMARILY IN SHEAR)
MAXIMUM ALLOWABLE
TORQUE LIMITS
TIGHTENING
Thread Size
Tension type nuts
Shear type nuts MS20364
Nuts MS20365 and
Nuts MS20364 and
MS20365 and AN310
and AN320 (24,000 psi in
AN310 (90,000 psi in
AN320 (54,000 psi in
(40,000 psi in bolts)
bolts)
bolts)
bolts)
FINE THREAD SERIES
8-36
12-15
7-9
20
12
10-32
20-25
12-15
40
25
1/4-28
50-70
30-40
100
60
5/16-24
100-140
60-85
225
140
3/8-24
160-190
95-110
390
240
7/16-20
450-500
270-300
840
500
1/2-20
480-690
290-410
1100
660
9/16-18
800-1000
480-600
1600
960
5/8-18
1100-1300
600-780
2400
1400
3/4-16
2300-2500
1300-1500
5000
3000
7/8-14
2500-3000
1500-1800
7000
4200
1-14
3700-5500
2200-3300*
10,000
6000
1-1/8-12
5000-7000
3000-4200*
15,000
9000
1-1/4-12
9000-11,000
5400-6600*
25,000
15,000
COARSE THREAD SERIES
8-32
12-15
7-9
20
12
10-24
20-25
12-15
35
21
1/4-20
40-50
25-30
75
45
5/16-18
80-90
48-55
160
100
3/8-16
160-185
95-100
275
170
7/16-14
235-255
140-155
475
280
1/2-13
400-480
240-290
880
520
9/16-12
500-700
300-420
1100
650
5/8-11
700-900
420-540
1500
900
3/4-10
1150-1600
700-950
2500
1500
7/8-9
2200-3000
1300-1800
4600
2700
The above torque values may be used for all cadmium-plated steel nuts of the fine or coarse thread series which have approximately equal number of threads and equal face bearing areas. * Estimated corresponding values.
7-44. CLOSE-TOLERANCE BOLTS.
Close-tolerance, hex head, machine bolts (AN173 through AN186), 100-degree counter­sunk head, close-tolerance, high-strength bolts (NAS333 through NAS340), hex head, close-tolerance, short thread, titanium alloy bolts (NAS653 through NAS658), 100-degree countersunk flathead, close-tolerance titanium
alloy bolts (NAS663 through NAS668), and
drilled hex head close-tolerance titanium alloy
bolts (NAS673 through NAS678), are used in
applications where two parts bolted together are subject to severe load reversals and vibra­tion. Because of the interference fit, this type
of bolt may require light tapping with a mallet to set the bolt shank into the bolt hole.
NOTE: Elimination of friction in in­terference fit applications may some­times be attained by placing the bolt in a freezer prior to installation. When this procedure is used, the bolt should be allowed to warm up to am­bient temperature before torquing.
CAUTION: Caution must be exer­cised in the use of close-tolerance bolts for all critical applications, such as
Par 7-43
Page 7-9
AC 43.13-1B
9/8/98
landing gear, control systems, and helicopter rotary controls. Do not substitute for close-tolerance fasteners without specific instructions from the aircraft manufacturer or the FAA.
7-45. INTERNAL WRENCHING BOLTS (NAS144 THROUGH NAS158 AND NAS172 THROUGH NAS176). These are high-strength bolts used primarily in tension appli­cations. Use a special heat-treated washer (NAS143C) under the head to prevent the large radius of the shank from contacting only the sharp edge of the hole. Use a special heat-treated washer (NAS143) under the nut.
7-46. INTERNAL WRENCHING BOLTS (MS20004 THROUGH MS20024) AND SIX HOLE, DRILLED SOCKET HEAD BOLTS (AN148551 THROUGH AN149350). These are very similar to the bolts in paragraph 7-45, except these bolts are made from different al­loys. The NAS144 through NAS158 and NAS172 through NAS176 are interchangeable
with MS20004 through MS20024 in the same
thread configuration and grip lengths. The AN148551 through AN149350 have been su­perseded by MS9088 through MS9094 with
the exception of AN149251 through 149350, which has no superseding MS standard.
7-47. TWELVE POINT, EXTERNAL WRENCHING BOLTS, (NAS624 THROUGH NAS644). These bolts are used primarily in high-tensile, high-fatigue strength applications. The twelve point head, heat-resistant machine bolts (MS9033 through
MS9039), and drilled twelve point head ma­chine bolts (MS9088 through MS9094), are similar to the (NAS624 through NAS644); but are made from different steel alloys, and their shanks have larger tolerances.
7-48. CLOSE-TOLERANCE SHEAR BOLTS (NAS464). These bolts are designed for use where stresses normally are in shear only. These bolts have a shorter thread than bolts designed for torquing.
7-49. NAS6200 SERIES BOLTS. These are close tolerance bolts and are available in two oversized diameters to fit slightly elon­gated holes. These bolts can be ordered with an "X" or "Y" after the length, to designate the oversized grip portion of the bolt (i.e., NAS6204-6X for a 1/4 inch bolt with a 1/64 inch larger diameter). The elongated hole may have to be reamed to insure a good fit.
7-50. CLEVIS BOLTS (AN21
THROUGH AN36). These bolts are only used in applications subject to shear stress, and are often used as mechanical pins in control systems.
7-51. EYEBOLTS (AN42 THROUGH AN49). These bolts are used in applications where external tension loads are to be applied. The head of this bolt is specially designed for the attachment of a turnbuckle, a clevis, or a cable shackle. The threaded shank may or may not be drilled for safetying.
7-52.-7-62. [RESERVED.]
Page 7-10
Par 7-44
9/8/98
AC 43.13-1B
SECTION 4. NUTS
7-63. GENERAL. Aircraft nuts are avail­able in a variety of shapes, sizes, and material strengths. The types of nuts used in aircraft structures include castle nuts, shear nuts, plain nuts, light hex nuts, checknuts, wingnuts, and sheet spring nuts. Many are available in either self-locking or nonself-locking style. Typical nut types are shown in table 7-13. Refer to the aircraft manufacturer's structural repair man­ual, the manufacturer's engineering depart­ment, or the FAA, before replacing any nut with any other type.
7-64. SELF-LOCKING NUTS. These nuts are acceptable for use on certificated aircraft subject to the aircraft manufacturer's recom­mended practice sheets or specifications. Two types of self-locking nuts are currently in use, the all-metal type, and the fiber or nylon type.
a. DO NOT use self-locking nuts on parts subject to rotation.
b. Self-locking castellated nuts with cotter pins or lockwire may be used in any system.
c. Self-locking nuts should not be used with bolts or screws on turbine engine air­planes in locations where the loose nut, bolt, washer, or screw could fall or be drawn into the engine air intake scoop.
d. Self-locking nuts should not be used with bolts, screws, or studs to attach access panels or doors, or to assemble any parts that are routinely disassembled before, or after each flight. They may be used with anti-friction bearings and control pulleys, provided the in­ner race of the bearing is secured to the sup­porting structure by the nut and bolt.
e. Metal locknuts are constructed with either the threads in the locking insert, out-of-round with the load-carrying section, or with a saw-cut insert with a pinched-in thread in the locking section. The locking action of the all-metal nut depends upon the resiliency of the metal when the locking section and load-carrying section are engaged by screw threads. Metal locknuts are primarily used in high tem­perature areas.
f. Fiber or nylon locknuts are con­structed with an unthreaded fiber or nylon locking insert held securely in place. The fiber or nylon insert provides the locking action be­cause it has a smaller diameter than the nut. Fiber or nylon self-locking nuts are not in­stalled in areas where temperatures exceed 250 °F. After the nut has been tightened, make sure the bolt or stud has at least one thread showing past the nut. DO NOT reuse a fiber or nylon locknut, if the nut cannot meet the minimum prevailing torque values. (See ta­ble 7-2.)
g. Self-locking nut plates are produced in a variety of forms and materials for riveting or welding to aircraft structures or parts. Certain applications require the installation of self-locking nuts in channel arrangement permit­ting the attachment of many nuts in a row with only a few rivets.
7-65. NUT IDENTIFICATION FIN­ISHES. Several types of finishes are used on self-locking nuts. The particular type of finish is dependent on the application and tempera­ture requirement. The most commonly used finishes are described briefly as follows.
Par 7-63
Page 7-11
AC 43.13-1B
9/8/98
Table 7-2. Minimum prevailing torque values for re­used self-locking nuts.
(3) Iridescent Dichromate. Cadmium-plated work is dipped in a solution of sodium dichromate and takes on a surface film of basic chromium chromate which resists corrosion. Finish is yellow to brown in color.
NOTE: Cadmium-plated nuts are re­stricted for use in temperatures not to exceed 450 °F. When used in tem­peratures in excess of 450 °F, the cadmium will diffuse into the base ma­terial causing it to become very brittle and subject to early failure.
b. Silver plating. Silver plating is applied to locknuts for use at higher temperatures. Important advantages are its resistance to ex­treme heat (1,400 °F) and its excellent lubri­cating characteristics. Silver resists galling and seizing of mating parts when subjected to heat or heavy pressure.
c. Anodizing for Aluminum. An inor­ganic oxide coating is formed on the metal by connecting the metals and anodes in a suitable electrolyte. The coating offers excellent corro­sion resistance and can be dyed in a number of colors.
d. Solid Lubricant Coating. Locknuts are also furnished with molybdenum disulfide for lubrication purposes. It provides a clean, dry, permanently-bonded coating to prevent seizing and galling of threads. Molybdenum disulfide is applied to both cadmium and sil­ver-plated parts. Other types of finishes are available, but the finishes described in this chapter are the most widely used.
7-66. CASTLE NUT (AN310). The castle nut is used with drilled shank hex head bolts, clevis bolts, drilled head bolts, or studs that are subjected to tension loads. The nut has slots or castellations cut to accommodate a cotter pin or safety wire as a means of safetying.
FINE THREAD SERIES |
THREAD SIZE
MINIMUM PREVAILING TORQUE
7/16 - 20
8 inch-pounds
1/2 - 20
10 inch-pounds
9/16 - 18
13 inch-pounds
5/8 -18
18 inch-pounds
3/4 - 16
27 inch-pounds
7/8 - 14
40 inch-pounds
1 - 14
55 inch-pounds
1-1/8 - 12
73 inch-pounds
1-1/4 - 12
94 inch-pounds
COARSE THREAD SERIES |
THREAD SIZE
MINIMUM PREVAILING TORQUE
7/16 - 14
8 inch-pounds
1/2 - 13
10 inch-pounds
9/16 - 12
14 inch-pounds
5/8 - 11
20 inch-pounds
3/4 - 10
27 inch-pounds
7/8 - 9
40 inch-pounds
1 - 8
51 inch-pounds
1-1/8 - 8
68 inch-pounds
1-1/4 - 8
88 inch-pounds
a. Cadmium-Plating. This is an electro-lytically deposited silver-gray plating which provides exceptionally good protection against corrosion, particularly in salty atmosphere, but is not recommended in applications where the temperature exceeds 450 °F. The following additional finishes or refinements to the basic cadmium can be applied.
(1) Chromic Clear Dip. Cadmium sur­faces are passivated, and cyanide from the plating solution is neutralized. The protective film formed gives a bright, shiny appearance, and resists staining and finger marks.
(2) Olive Drab Dichromate. Cadmium-plated work is dipped in a solution of chromic acid, nitric acid, acetic acid, and a dye which produces corrosion resistance.
Page 7-12
Par 7-65
9/8/98
AC 43.13-1B
7-67. CASTELLATED SHEAR NUT (AN320). The castellated shear nut is de­signed for use with hardware subjected to shear stress only.
7-68. PLAIN NUT (AN315 AND AN335).
The plain nut is capable of withstanding large tension loads; however, it requires an auxiliary locking device, such as a checknut or safety wire. Use of this type on aircraft structures is limited.
7-69. LIGHT HEX NUTS (AN340 AND AN345). These nuts are used in nonstructural applications requiring light tension. Like the AN315 and AN335, they require a locking de­vice to secure them.
7-71. WINGNUTS (AN350). The wingnut is used where the desired torque is obtained by use of the fingers or handtools. Wingnuts are normally drilled to allow safetying with safety wire.
7-72. SHEET SPRING NUTS (AN365).
Sheet spring nuts are commonly called speed nuts. They are used with standard and sheet metal self-tapping screws in nonstructural ap­plications. They are used to support line and conduit clamps, access doors, etc. Their use should be limited to applications where they were originally used in assembly of the air­craft.
7-73.-7-84. RESERVED.
7-70. CHECKNUT (AN316). The checknut is used as a locking device for plain nuts, screws, threaded rod ends, and other devices.
Par 7-67
Page 7-13 (and 7-14)
9/8/98
AC 43.13-1B
SECTION 5. WASHERS
7-85. GENERAL. The type of washers used
in aircraft structure are plain washers, , and special washers. Typical washer types are shown in table 7-14.
7-86. PLAIN WASHERS (AN960 AND
AN970). Plain washers are widely used with hex nuts to provide a smooth bearing surface, act as a shim to obtain the proper grip length, and to position castellated nuts in relation to drilled cotter pin holes in bolts. Use plain washers under lock washers to prevent damage to bearing surfaces. Cadmium-plated steel washers are recommended for use under boltheads and nuts used on aluminum alloy or magnesium structures to prevent corrosion. The AN970 steel washer provides a larger bearing surface than the plain type, and is often used in wooden structures under boltheads and nuts to prevent local crushing of the surface.
7-87. LOCKWASHERS (AN935 AND
AN936). Lock washers may be used with ma­chine screws or bolts whenever the self-locking or castellated type nut is not applica­ble. Do not use lock washers where frequent removal is required, in areas subject to corro­sion, or in areas exposed to airflow. Use a plain washer between the lock washer and material to prevent gouging the surface of the metal.
CAUTION: Lock washers are not to be used on primary structures, secon­dary structures, or accessories where failure might result in damage or dan­ger to aircraft or personnel.
7-88. BALL SOCKET AND SEAT WASHERS (AN950 AND AN955). Ball socket and seat washers are used in special ap­plications where the bolt is installed at an an­gle to the surface or when perfect alignment with the surface is required. These washers are used together as a pair.
7-89. TAPER PIN WASHERS (AN975).
Taper pin washers are used with the threaded taper pin. NAS143 and MS20002 washers are used with NAS internal wrenching bolts and internal wrenching nuts. They may be plain or countersunk. The countersunk washer (desig­nated as NAS143C and MS20002C) is used to seat the bolthead shank radius, and the plain washer is used under the nut.
7-90.—7-100. [RESERVED.]
Par 7-85
Page 7-15 (and 7-16)
9/8/98
AC 43.13-1B
SECTION 6. PINS
7-101. TAPER PINS. Plain (AN385) and threaded (AN386) taper pins are used in joints which carry shear loads and where the absence of play is essential. The plain taper pin is usu­ally drilled and secured with wire. The threaded taper pin is used with a taper-pin washer (AN975) and shear nut (safetied with a cotter pin) or self-locking nut (if undrilled). Typical pin types are shown in table 7-15.
7-102. FLATHEAD PINS (AN392 THROUGH AN406). Commonly called a clevis pin, this pin is used in conjunction with tie-rod terminals and in secondary controls which are not subject to continuous operation. The pin is normally installed with the head up, or forward, to prevent loss should the cotter pin fail or work out.
7-103. COTTER PINS (AN380). Cotter pins are used for securing bolts, screws, nuts, and pins. Use AN381 or MS24665 cotter pins in locations where nonmagnetic material or re­sistance to corrosion is desired. Cotter pins should not be reused.
7-104. SPRING PINS. The spring pin is
designed for use in double-shear applications. The pins are manufactured with the diameter greater than the holes in which they are to be used. Spring pins are stronger than mild car­bon steel straight pins, taper pins, or grooved pins of the equivalent size. The spring pin is compressed as it is driven into the hole, and exerts continuous spring pressure against the sides of the hole to prevent loosening by vi­bration. Spring pins require no other means of securing, and can be used inside one another to increase shear strength.
a. Be careful when using these pins,
since spring-pin performance depends entirely on the fit and the durability of the fit under
vibration or repeated load conditions (espe­cially in soft materials, such as aluminum al­loys and magnesium). They should not be used in an aircraft component or system where the loss or failure of the pin might endanger safe flight.
b. The joints where spring pins are used
for fastening shall be designed like riveted and bolted joints. Spring pins should not be mixed with other structural fasteners in the same joint. These pins, for primary structural appli­cations, should be used only where there will be no rotation or relative movement of the joint. Spring pins may be reused if a careful inspection reveals no deformation of the pin or hole.
c. Be careful to observe that the hole has not enlarged or deformed preventing proper functioning of the spring pin. Where hole misalignment results in the pin gap closing or necessitates excess inserting force, the spring pin will not be used. The spring pin should not be used as a substitute for a cotter pin. When a spring pin is used in a clevis joint, it is recommended that the pin be held by the outer members of the unit for maximum efficiency and reduced maintenance.
7-105. QUICK-RELEASE PINS. These
pins are used in some applications where rapid removal and replacement of equipment is nec­essary. When equipment is secured with these pins, no binding of the spindle should be pres­ent. Spindle binding could cause the locking balls to remain in the open position which could result in the pin falling out under vibra­tion.
7-106—7-121. [RESERVED.]
Par 7-101
Page 7-17 (and 7-18)
9/8/98
AC 43.13-1B
SECTION 7. SAFETYING
7-122. GENERAL. The word safetying is a term universally used in the aircraft industry. Briefly, safetying is defined as: "Securing by various means any nut, bolt, turnbuckle etc., on the aircraft so that vibration will not cause it to loosen during operation." These practices are not a means of obtaining or maintaining torque, rather a safety device to prevent the disengagement of screws, nuts, bolts, snap rings, oil caps, drain cocks, valves, and parts. Three basic methods are used in safetying; safety-wire, cotter pins, and self-locking nuts. Retainer washers and pal nuts are also some­times used.
a. Wire, either soft brass or steel is used on cylinder studs, control cable turnbuckles, and engine accessory attaching bolts.
b. Cotter pins are used on aircraft and engine controls, landing gear, and tailwheel as­semblies, or any other point where a turning or actuating movement takes place.
c. Self-locking nuts are used in applica­tions where they will not be removed often. Repeated removal and installation will cause the self-locking nut to lose its locking feature. They should be replaced when they are no longer capable of maintaining the minimum prevailing torque. (See table 7-2.)
d. Pal or speed nuts include designs which force the nut thread against the bolt or screw thread when tightened. These nuts should never be reused and should be replaced with new ones when removed.
7-123. SAFETY WIRE. Do not use stain­less steel, monel, carbon steel, or aluminum alloy safety wire to secure emergency mecha­nisms such as switch handles, guards covering handles used on exits, fire extinguishers,
emergency gear releases, or other emergency equipment. Some existing structural equip­ment or safety-of-flight emergency devices re­quire copper or brass safety wire (.020 inch di­ameter only). Where successful emergency operation of this equipment is dependent on shearing or breaking of the safety wire, par­ticular care should be used to ensure that safe-tying does not prevent emergency operation.
a. There are two methods of safety wiring; the double-twist method that is most commonly used, and the single-wire method used on screws, bolts, and/or nuts in a closely-spaced or closed-geometrical pattern such as a triangle, square, rectangle, or circle. The sin­gle-wire method may also be used on parts in electrical systems and in places that are diffi­cult to reach. (See figures 7-3 and 7-3a.)
b. When using double-twist method of
safety wiring, .032 inch minimum diameter wire should be used on parts that have a hole diameter larger than .045 inch. Safety wire of .020 inch diameter (double strand) may be used on parts having a nominal hole diameter between .045 and .062 inch with a spacing between parts of less than 2 inches. When using the single-wire method, the largest size wire that the hole will accommodate should be used. Copper wire (.020 inch diameter), alu­minum wire (.031 inch diameter), or other similar wire called for in specific technical or­ders, should be used as seals on equipment such as first-aid kits, portable fire extinguish­ers, emergency valves, or oxygen regulators.
CAUTION: Care should be taken not to confuse steel with aluminum wire.
c. A secure seal indicates that the com­ponent has not been opened. Some emergency devices require installation of brass or soft
Par 7-122
Page 7-19
AC 43.13-1B
9/8/98
bqltheaos castle nuts
NOTE
the safetywire is shown in stalled for right-hand threads the SaFETYWIRE
IS ROUTED IN THE OPPOSITE DIRECTION FOfl LEFT-HAND THBtAfjS
Figure 7-3. Securing screws, nuts, bolts, and snaprings.
6t08 twist per inch
copper shear safety wire. Particular care should be exercised to ensure that the use of safety wire will not prevent emergency opera­tion of the devices.
7-124. SAFETY-WIRING PROCEDURES.
There are many combinations of safety wiring with certain basic rules common to all appli­cations. These rules are as follows.
a. When bolts, screws, or other parts are
closely grouped, it is more convenient to safety wire them in series. The number of bolts, nuts, screws, etc., that may be wired together de­pends on the application.
b. Drilled boltheads and screws need not be safety wired if installed with self-locking nuts.
Figure 7-3a. Wire twisting by hand.
Page 7-20
Par 7-123
9/8/98
AC 43.13-1B
c. To prevent failure due to rubbing or vibration, safety wire must be tight after in­stallation.
d. Safety wire must be installed in a man­ner that will prevent the tendency of the part to loosen.
e. Safety wire must never be over-stressed. Safety wire will break under vibra­tions if twisted too tightly. Safety wire must be pulled taut when being twisted, and main­tain a light tension when secured. (See fig­ure 7-3a.)
f. Safety-wire ends must be bent under and inward toward the part to avoid sharp or projecting ends, which might present a safety hazard.
g. Safety wire inside a duct or tube must not cross over or obstruct a flow passage when an alternate routing can be used.
(1) Check the units to be safety wired to make sure that they have been correctly tor-qued, and that the wiring holes are properly aligned to each other. When there are two or more units, it is desirable that the holes in the units be aligned to each other. Never overtor-que or loosen to obtain proper alignment of the holes. It should be possible to align the wiring holes when the bolts are torqued within the specified limits. Washers may be used (see paragraph 7-37) to establish proper alignment. However, if it is impossible to obtain a proper alignment of the holes without undertorquing or overtorquing, try another bolt which will permit proper alignment within the specified torque limits.
(2) To prevent mutilation of the twisted section of wire, when using pliers, grasp the wires at the ends. Safety wire must not be nicked, kinked, or mutilated. Never twist the wire ends off with pliers; and, when cutting off
ends, leave at least four to six complete turns (1/2 to 5/8 inch long) after the loop. When removing safety wire, never twist the wire off with pliers. Cut the safety wire close to the hole, exercising caution.
h. Install safety wire where practicable with the wire positioned around the head of the bolt, screw, or nut, and twisted in such a man­ner that the loop of the wire fits closely to the contour of the unit being safety wired.
7-125. TWISTING WITH SPECIAL TOOLS. Twist the wire with a wire twister as follows. (See figure 7-4.)
CAUTION: When using wire twist­ers, and the wire extends 3 inches be­yond the jaws of the twisters, loosely wrap the wire around the pliers to prevent whipping and possible per­sonal injury. Excessive twisting of the wire will weaken the wire.
a. Grip the wire in the jaws of the wire twister and slide the outer sleeve down with your thumb to lock the handles or lock the spring-loaded pin.
b. Pull the knob, and the spiral rod spins and twists the wire.
c. Squeeze handles together to release wire.
7-126. SECURING OIL CAPS, DRAIN
COCKS, AND VALVES. (See figure 7-4a.) When securing oil caps and drain cocks, the safety wire should be anchored to an adjacent fillister-head screw. This method of safety wiring is applied to wingnuts, filler plugs, sin­gle-drilled head bolts, fillister-head screws, etc.; which are safety wired individually. When securing valve handles in the vertical position, the wire is looped around the threads of the pipe leading into one side of the valve,
Par 7-124
Page 7-21
AC 43.13-1B
9/8/98
double-twisted around the valve handle, and anchored around the threads of the pipe lead­ing into the opposite side of the valve. When castellated nuts are to be secured with safety wire, tighten the nut to the low side of the se­lected torque range, unless otherwise specified; and, if necessary, continue tightening until a slot lines with the hole. In blind tapped hole applications of bolts or castellated nuts on studs, the safety wiring should be in accor­dance with the general instructions of this chapter. Hollow-head bolts are safetied in the manner prescribed for regular bolts.
NOTE: Do not loosen or tighten properly tightened nuts to align safety-wire holes.
NOTE: Although there are numerous safety wiring techniques used to se­cure aircraft hardware, practically all are derived from the basic examples shown in figures 7-5 through 7-5b.
Figure 7-4. Use of a typical wire twister.
VALVES
Figure 7-4a. Securing oil caps, drain cocks, and valves.
Page 7-22
Par 7-126
9/8/98
AC 43.13-1B
EXAMPLE 1 EXAMPLE 2 EXAMPLE 3 EXAMPLE 4
Examples 1, 2, 3, and 4 apply to all types of bolts, fillister-head screws, square-head plugs, and other similar parts which are wired so that the loosening tendency of either part is counteracted by tightening of the other part. The direction of twist from the second to the third unit is counterclockwise in exam­ples 1, 3, and 4 to keep the loop in position against the head of the bolt. The direction of twist from the second to the third unit in example 2 is clockwise to keep the wire in position around the second unit. The wire entering the hole in the third unit will be the lower wire, except example 2, and by making a counterclockwise twist after it leaves the hole, the loop will be secured in place around the head of that
bolt.
EXAMPLE 5 EXAMPLE 6 EXAMPLE 7 EXAMPLE 8
Examples 5, 6, 7, & 8 show methods for wiring various standard items, NOTE: Wire may be wrapped over the unit rather than around it when wiring castellated nuts or on other items when there is a clear­ance problem.
EXAMPLE 9
Example 9 shows the method for wiring bolts in different planes. Note that wire should always be ap­plied so that tension is in the tightening direction.
Figure 7-5. Safety-wiring procedures.
EXAMPLE 10
Hollow-head plugs shall be wired as shown with the tab bent inside the hole to avoid snags and possible injury to person­nel working on the engine.
EXAMPLE 11
Correct application of single wire to closely spaced multi­ple group.
Par 7-126
Page 7-23
AC 43.13-1B
9/8/98
EXAMPLE 14
Example 14 shows bolt wired to a right-angle brac ket with the wi re wrapped around the bracket.
EXAMPLE 15
Example 15 shows correct method for wiring adjustable connecting rod.
EXAMPLE 16
Example 16 shows correct method for wiring the cou­pling nut on flexible line to the straight connector brazed on rigid tube.
EXAMPLE 17
EXAMPLE 18
EXAMPLE 19
EXAMPLE 20
EXAMPLE 21
Fittings incorporating wire lugs shall be wired as shown in Exam­ples 17 and 18. Where no lock-wire lug is provided, wire should be applied as shown in examples 19 and 20 with caution being exerted to ensure that wire is wrapped tightly around the fitting.
Small size coupling nuts shall be wired by wrapping the wire around the nut and inserting it through the holes as shown.
Figure 7-5a. Safety-wiring procedures.
Page 7-24
Par 7-126
9/8/98
AC 43.13-1B
EXAMPLE 24
Coupling nuts on a tee shall be wired, as shown above, so that tension is always in the tightening di­rection.
EXAMPLE 25 EXAMPLE 26
Straight Connector (Bulkhead Type)
EXAMPLE 27 EXAMPLE 28
Examples 26, 27, and 28 show the proper method for wiring various standard fittings with checknut wired independently so that it need not be disturbed when removing the coupling nut.
Figure 7-5b. Safety-wiring procedures.
Par 7-126
Page 7-25
AC 43.13-1B
9/8/98
7-127. SECURING WITH COTTER PINS.
a. Cotter pins are used to secure such items as bolts, screws, pins, and shafts. Their use is favored because they can be removed and installed quickly. The diameter of the cotter pins selected for any application should be the largest size that will fit consistent with the diameter of the cotter pin hole and/or the slots in the nut. Cotter pins should not be re­used on aircraft.
b. To prevent injury during and after pin installation, the end of the cotter pin can be rolled and tucked.
NOTE: In using the method of cotter pin safetying, as shown in figures 7-6 and 7-7, ensure the prong, bent over the bolt, is seated firmly against the bolt shank, and does not exceed bolt diameter. Also, when the prong is bent over the nut, ensure the bent prong is down and firmly flat against the nut and does not contact the sur­face of the washer.
Figure 7-6. Securing with cotter pins.
TO SHAN
Figure 7-7. Alternate method for securing with cotter pins.
7-128.—7-139. [RESERVED.]
Page 7-26
Par 7-127
9/8/98
AC 43.13-1B
SECTION 8. INSPECTION AND REPAIR OF CONTROL CABLES
AND TURNBUCKLES
7-140. GENERAL. Aircraft control cables are generally fabricated from carbon steel or corrosion-resistant steel wire of either flexible or nonflexible-type construction.
7-141. CABLE DEFINITIONS. The fol­lowing cable components are defined in accor­dance with Military Specifications MIL-W-83420, MIL-C-18375, and MIL-W-87161.
a. Wire Center. The center of all strands shall be an individual wire and shall be desig­nated as a wire center.
b. Strand Center or Core. A strand cen­ter is a single, straight strand made of pre­formed wires, similar to the other strands comprising the cable, in arrangement and number of wires.
c. Independent Wire Rope Center (IWRC) 7 by 7. A 7 by 7 independent wire rope center as specified herein shall consist of a cable or wire rope of six strands of seven wires each, twisted or laid around a strand center or core consisting of seven wires.
7-142. FLEXIBLE CABLES. Flexible, preformed, carbon steel, Type I, composition A cables, MIL-W-83420, are manufactured from steel made by the acid-open-hearth, basic-open hearth, or electric-furnace process. The wire used is coated with pure tin or zinc. Flexible, preformed, corrosion-resistant, Type I, compo­sition B cables, MIL-W-87161,
MIL-W-83420, and MIL-C-18375 are manu­factured from steel made by the electric-furnace process. (See table 7-3 and fig­ure 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 ta­ble 7-3. The 3 by 7 cable consists of three
strands of seven wires each. There is no core in this construction. The 3 by 7 cable has a length of lay of not more than eight times or less than five times the nominal cable diame­ter. The 7 by 7 cable consists of six strands, of seven wires each, laid around a center strand of seven wires. The wires are laid so as to de­velop a cable which has the greatest bending and wearing properties. The 7 by 7 cable has a length of lay of not more than eight times or less than six times the cable diameter. The 7 by 19 cable consists of six strands laid around a center strand in a clockwise direction. The wires composing the seven individual strands are laid around a center wire in two layers. The center core strand consists of a lay of six wires laid around the central wire in a clockwise direction and a layer of 12 wires laid around this in a clockwise direction. The six outer strands of the cable consist of a layer of six wires laid around the center wire in a counterclockwise direction and a layer of 12 wires laid around this in a counterclockwise direction. The 6 by 19 cable consists of six strands of 19 wires each, laid around a 7 by 7. MIL-C-18375 cable, although not as strong as MIL-W-83420, is equal in corrosion resistance and superior in non-magnetic and coefficient of thermal expansion properties.
7-143. NYLON-COATED CABLES.
a. Nylon-coated cable is made by ex­truding a flexible nylon coating over corro­sion-resistant steel (CRES) cable. The bare CRES cable must conform and be qualified to MIL-W-83420. After coating, the jacketed ca­ble must still conform to MIL-W-83420.
b. The service life of nylon-coated cable
is much greater than the service life of the same cable when used bare. Most cable wear occurs at pulleys where the cable bends. Wear
Par 7-140
Page 7-27
AC 43.13-1B
9/8/98
Table 7-3. Flexible cable construction and physical properties.
MINIMUM BREAKING STRENGTH (Pounds)
NOMINAL DIAMETER OF WIRE
ROPE
CABLE
CONSTRUCTION
TOLERANCE ON
DIAMETER
(PLUS ONLY)
ALLOWABLE
INCREASE OF
DIAMETER
AT CUT END
MIL-W-83420
COMP A
MIL-W-83420
COMP B
(CRES)
MIL-C-18375
(CRES)
INCHES
INCHES
INCHES
LBS
LBS
LBS
1/32
3 x 7
0.006
0.006
110
110
3/64
7 x 7
0.008
0.008
270
270
1/16
7 x 7
0.010
0.009
480
480
360
1/16
7 x 19
0.010
0.009
480
480
3/32
7 x 7
0.012
0.010
920
920
700
3/32
7 x 19
0.012
0.010
1,000
920
1/8
7 x 19
0.014
0.011
2,000
1,760
1,300
5/32
7 x 19
0.016
0.017
2,800
2,400
2,000
3/16
7 x 19
0.018
0.019
4,200
3,700
2,900
7/32
7 x 19
0.018
0.020
5,600
5,000
3,800
1/4
7 x 19
0.018
0.021
7,000
6,400
4,900
9/32
7 x 19
0.020
0.023
8,000
7,800
6,100
5/16
7 x 19
0.022
0.024
9,800
9,000
7,600
11/32
7 x 19
0.024
0.025
12,500
3/8
7 x 19
0.026
0.027
14,400
12,000
11,000
7/16
6 x 19 IWRC
0.030
0.030
17,600
16,300
14,900
1/2
6 x 19 IWRC
0.033
0.033
22,800
22,800
19,300
9/16
6 x 19 IWRC
0.036
0.036
28,500
28,500
24,300
5/8
6 x 19 IWRC
0.039
0.039
35,000
35,000
30,100
3/4
6 x 19 IWRC
0.045
0.045
49,600
49,600
42,900
7/8
6 x 19 IWRC
0.048
0.048
66,500
66,500
58,000
1
6 x 19 IWRC
0.050
0.050
85,400
85,400
75,200
1 - 1/8
6 x 19 IWRC
0.054
0.054
106,400
106,400
1 - 1/4
6 x 19 IWRC
0.057
0.057
129,400
129,400
1 - 3/8
1 - 1/2
6 x 19 IWRC 6 x 19 IWRC
0.060
0.062
0.060
0.062
153,600
180,500
153,600
180,500
is caused by friction between strands and be­tween wires. In bare cable, this is aggravated by dirt and grit working its way into the cable; and the lubricant working its way out leaving dry, dirty wires rubbing against each other. In long, straight runs of cable, vibration work-hardens the wires causing the brittle wires to fracture with eventual failure of the cable.
c. The nylon-jacket protects the cable in a threefold manner. It keeps the lubricant from oozing out and evaporating, it keeps dirt and grit out, and it dampens the vibrations,
thereby, greatly reducing their effect on the ca­ble.
7-144. NONFLEXIBLE CABLES. (Refer
to table 7-4 and figure 7-9.) Nonflexible, pre­formed, carbon steel cables, MIL-W-87161, composition A, are manufactured by the same processes as MIL-W-83420, composition B, flexible corrosion-resistant steel cables. The nonflexible steel cables are of the 1 by 7 (Type I) or 1 by 19 (Type II) construction ac­cording to the diameter as specified in ta­ble 7-4. The 1 by 7 cable consists of six
Page 7-28
Par 7-143
9/8/98
AC 43.13-1B
DIAMETER
DIAMETER
DIAMETER
3X7
DIAMETER
7X7
7X19
6X19
Figure 7-8. Flexible cable cross section.
TABLE 7-4. Nonflexible cable construction and physical properties.
STRAND TYPE
NOMINAL
DIAMETER
OF WIRE
STRAND
In.
TOLERANCE
ON DIAMETER (Plus Only)
In.
ALLOWABLE
INCREASE
IN
DIAMETER
AT THE END
In.
CONSTRUCTION
MIL-W-87161
MINIMUM
BREAK STRENGTH
COMP A & B
Lbs.
I
1/32
0.003
0.006
1 x 7
185
I
3/64
0.005
0.008
1 x 7
375
II
3/64
0.005
0.008
1 x 19
375
I
1/16
0.006
0.009
1 x 7
500
1/16
0.006
0.009
1 x 19
500
5/64
0.008
0.009
1 x 19
800
3/32
0.009
0.010
1 x 19
1,200
7/64
0.009
0.010
1 x 19
1,600
1/8
0.013
0.011
1 x 19
2,100
5/32
0.013
0.016
1 x 19
3,300
3/16
0.013
0.019
1 x 19
4,700
7/32
0.015
0.020
1 x 19
6,300
1/4
0.018
0.021
1 x 19
8,200
5/16
0.022
0.024
1 x 19
12,500
3/8
0.026
0.027
1 x 19
17,500
7-145. CABLE SPECIFICATIONS. Cable diameter and strength data are given in ta­ble 7-3 and table 7-4. These values are accept­able for repair and modification of civil air­craft.
7-146. CABLE PROOF LOADS. Cable terminals and splices should be tested for proper strength before installation. Gradually apply a test load equal to 60 percent of the ca­ble-breaking strengths given in table 7-3 and
Figure 7-9. Nonflexible cable cross section.
wires laid around a center wire in a counter­clockwise direction. The 1 by 19 cable con­sists of a layer of six wires laid around a center wire in a clockwise direction plus twelve wires laid around the inner strand in a counterclock­wise direction.
Par 7-144
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AC 43.13-1B
9/8/98
table 7-4, for a period of 3 minutes. Place a suitable guard over the cable during the test to prevent injury to personnel in the event of ca­ble failure.
7-147. REPLACEMENT OF CABLES.
Replace control cables when they become worn, distorted, corroded, or otherwise dam­aged. If spare cables are not available, prepare exact duplicates of the damaged cable. Use materials of the same size and quality as the original. Standard swaged cable terminals de­velop the full cable strength and may be sub­stituted for the original terminals wherever practical. However, if facilities and supplies are limited and immediate corrective action is necessary, repairs may be made by using cable bushings, eye splices, and the proper combina­tion of turnbuckles in place of the original in­stallation. (See figure 7-12(c).)
a. Location of Splices. Locate splices so that no portion of the splice comes closer than 2 inches to any fair-lead or pulley. Locate connections at points where jamming cannot occur during any portion of the travel of either the loaded cable or the slack cable in the de­flected position.
b. Cutting and Heating. Cut cables to length by mechanical means. The use of a torch, in any manner, is not permitted. Do not subject wires and cables to excessive tem­perature. Soldering the bonding braid to the control cable is not permitted.
c. Ball-and-Socket Type Terminals. Do
not use ball-and-socket type terminals or other types for general replacement that do not posi­tively prevent cable untwisting, except where they were utilized on the original installation by the aircraft manufacturer.
d. Substitution of Cable. Substitution of cable for hard or streamlined wires will not be
acceptable unless specifically approved by a representative of the FAA.
7-148. MECHANICALLY-FABRI­CATED CABLE ASSEMBLIES.
a. Swage-Type Terminals. Swage-type terminals, manufactured in accordance with AN, are suitable for use in civil aircraft up to, and including, maximum cable loads. When swaging tools are used, it is important that all the manufacturers' instructions, including "go and no-go" dimensions, be followed in detail to avoid defective and inferior swaging. Ob­servance of all instructions should result in a terminal developing the full-rated strength of the cable. Critical dimensions, both before and after swaging, are shown in table 7-5.
(1) Terminals. When swaging terminals onto cable ends, observe the following proce­dures.
(a) Cut the cable to the proper length allowing for growth during swaging. Apply a preservative compound to the cable ends be­fore insertion into the terminal barrel.
NOTE: Never solder cable ends to prevent fraying, since the presence of the solder will greatly increase the ten­dency of the cable to pull out of the terminal.
(b) Insert the cable into the terminal approximately 1 inch, and bend toward the terminal, then push the cable end entirely into the terminal barrel. The bending action puts a kink or bend in the cable end, and provides enough friction to hold the terminal in place until the swaging operation can be performed. Bending also tends to separate the strands in­side the barrel, thereby reducing the strain on them.
Page 7-30
Par 7-146
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AC 43.13-1B
Table 7-5. Straight-shank terminal dimensions. (Cross reference AN to MS: AN-666 to MS 21259, AN-667 to MS 20667, AN-668 to MS 20668, AN-669 to MS 21260.)
Before swaging
After swaging
Cable size (inches)
Wire strands
Outside diameter
Bore diameter
Bore length
Swaging length
Minimum breaking strength (pounds)
Shank
diameter *
1/16
7 x 7
0.160
0.078
1.042
0.969
480
0.138
3/32
7 x 7
.218
.109
1.261
1.188
920
.190
1/8
7 x 19
.250
.141
1.511
1.438
2,000
.219
5/32
7 x 19
.297
.172
1.761
1.688
2,800
.250
3/16
7 x 19
.359
.203
2.011
1.938
4,200
.313
7/32
7 x 19
.427
.234
2.261
2.188
5,600
.375
1/4
7 x 19
.494
.265
2.511
2.438
7,000
.438
9/32
7 x 19
.563
.297
2.761
2.688
8,000
.500
5/16
7 x 19
.635
.328
3.011
2.938
9,800
.563
3/8
7 x 19
.703
.390
3.510
3.438
14,400
.625
NOTE: If the terminal is drilled com­pletely through, push the cable into the terminal until it reaches the approxi­mate position shown in figure 7-10. If the hole is not drilled through, insert the cable until the end rests against the bottom of the hole.
cable slippage in the terminal and for cut or broken wire strands.
(e) Using a "go no-go" gauge or a micrometer, check the terminal shank diameter as shown in figure 7-11 and table 7-5.
Figure 7-10. Insertion of cable into terminal.
(c) Accomplish the swaging opera­tion in accordance with the instructions fur­nished by the manufacturer of the swaging equipment.
Figure 7-11. Gauging terminal shank after swaging.
(f) Test the cable by proof-loading it to 60 percent of its rated breaking strength.
(d) Inspect the terminal after swaging (2) Splicing. Completely severed ca-
to determine that it is free from the die irmife bles, or those badly damaged in a localized
and splits, and is not out-of-round. Check for area, may be repaired by the use of an eye
Par 7-148
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AC 43.13-1B
9/8/98
terminal bolted to a clevis terminal. (See fig­ure 7-12(a).) However, this type of splice can only be used in free lengths of cable which do not pass over pulleys or through fair-leads.
Figure 7-13. Typical terminal gauge.
(4) Cable slippage in terminal. Ensure that the cable is properly inserted in the termi­nal after the swaging operation is completed. Instances have been noted wherein only 1/4 inch of the cable was swaged in the termi­nal. Observance of the following precautions should minimize this possibility.
(a) Measure the length of the termi­nal end of the fitting to determine the proper length of cable to be inserted into the barrel of the fitting.
(b) Lay off this length at the end of the cable and mark with masking tape. Since the tape will not slip, it will provide a positive marking during the swaging process.
(c) After swaging, check the tape marker to make certain that the cable did not slip during the swaging operation.
(d) Remove the tape and paint the junction of the swaged fitting and cable with red tape.
(e) At all subsequent service inspec­tions of the swaged fitting, check for a gap in the painted section to see if cable slippage has occurred.
b. Nicopress Process. A patented process using copper sleeves may be used up to the full rated strength of the cable when the cable is looped around a thimble. This process may also be used in place of the five-tuck splice on
Figure 7-12. Typical cable splices.
(3) Swaged ball terminals. On some aircraft cables, swaged ball terminals are used for attaching cables to quadrants and special connections where space is limited. Single shank terminals are generally used at the cable ends, and double shank fittings may be used at either the end or in the center of the cable. Dies are supplied with the swaging machines for attaching these terminals to cables by the following method.
(a) The steel balls and shanks have a hole through the center, and are slipped over the cable and positioned in the desired loca­tion.
(b) Perform the swaging operation in accordance with the instructions furnished by the manufacturer of the swaging equipment.
(c) Check the swaged fitting with a "go no-go" gauge to see that the fitting is properly compressed, and inspect the physical condition of the finished terminal. (See fig­ure 7-13.)
Page 7-32
Par 7-148
9/8/98
AC 43.13-1B
cables up to and including 3/8 inch diameter. The use of sleeves that are fabricated of mate­rials other than copper will require engineering approval for the specific application by the FAA.
(1) Before undertaking a nicopress splice, determine the proper tool and sleeve for the cable to be used. Refer to table 7-6 and ta­ble 7-7 for details on sleeves, tools, and the number of presses required for the various sizes of aircraft cable. The tool must be in good working condition and properly adjusted to ensure a satisfactory splice.
(2) To compress a sleeve, have it well-centered in the tool groove with the major axis of the sleeve at right angles to the tool. If the sleeve appears to be out of line after the press is started, open the tool, re-center the sleeve, and complete the press.
c. Thimble-Eye Splice. Before under­taking a thimble-eye splice, initially position the cable so the end will extend slightly be­yond the sleeve, as the sleeve will elongate somewhat when it is compressed. If the cable end is inside the sleeve, the splice may not hold the full strength of the cable. It is desir­able that the oval sleeve be placed in close proximity to the thimble points, so that when compressed, the sleeve will contact the thimble as shown in figure 7-14. The sharp ends of the thimble may be cut off before being used; however, make certain the thimble is firmly secured in the cable loop after the splice has been completed. When using a sleeve requir­ing three compressions, make the center com­pression first, the compression next to the thimble second, and the one farthest from the thimble last.
d. Lap Splice. Lap or running splices may also be made with copper oval sleeves. When making such splices, it is usually neces­sary to use two sleeves to develop the full
Figure 7-14. Typical thimble-eye splice.
strength of the cable. The sleeves should be positioned as shown in figure 7-12(b), and the compressions made in the order shown. As in the case of eye splices, it is desirable to have the cable ends extend beyond the sleeves suffi­ciently to allow for the increased length of the compressed sleeves.
e. Stop Sleeves. Stop sleeves may be used for special cable end and intermediate fittings. They are installed in the same manner as nico-press oval sleeves.
NOTE: All stop sleeves are plain cop­per. Certain sizes are colored for iden­tification.
f. Terminal Gauge. To make a satisfac­tory copper sleeve installation, it is important that the amount of sleeve pressure be kept uni­form. The completed sleeves should be checked periodically with the proper gauge. Hold the gauge so that it contacts the major axis of the sleeve. The compressed portion at the center of the sleeve should enter the gauge opening with very little clearance, as shown in figure 7-15. If it does not, the tool must be adjusted accordingly.
g. Other Applications. The preceding in­formation regarding copper oval sleeves and stop sleeves is based on tests made with flexi­ble aircraft cable. The sleeves may also be
Par 7-148
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AC 43.13-1B
9/8/98
Table 7-6. Copper oval sleeve data.
Copper oval sleeve stock No.
Cable size
Plain
Plated*
Manual tool No.
Sleeve length before com­pression (ap-prox.) (inches)
Sleeve length
after com­pression (ap-prox.) (inches)
Number of presses
Tested strength (pounds)
3/64
18-11-B4
28-11-B4
51-B4-887
3/8
7/16
1
340
1/16
18-1-C
28-1-C
51-C-887
3/8
7/16
1
550
3/32
18-2-G
28-2-G
51-G-887
7/16
1/2
1
1,180
1/8
18-3-M
28-3-M
51-M-850
9/16
3/4
3
2,300
5/32
18-4-P
28-4-P
51-P-850
5/8
7/8
3
3,050
3/16
18-6-X
28-6-X
51-X-850
1
1 1/4
4
4,350
7/32
18-8-F2
28-8-F2
51-F2-850
7/8
1 1/16
4
5,790
1/4
18-10-F6
28-10-F6
3-F6-950
1 1/8
1 1/2
3
7,180
5/16
18-13-G9
28-13-G9
3-G9-950
1 1/4
1 5/8
3
11,130
No. 635 Hydraulic tool dies
3/8
18-23-H5
28-23-H5
Oval H5
1 1/2
1 7/8
1
16,800
7/16
18-24-J8
28-24-J8
Oval J8
1 3/4
2 1/8
2
19,700
1/2
18-25-K8
28-25-K8
Oval K8
1 7/8
2 1/2
2
25,200
9/16
18-27-M1
28-27-M1
Oval M1
2
2 5/8
3
31,025
5/8
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
280
1/16
871-1-C
51-C-887
7/32
13/64
525
3/32
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
1,200
3/16
871-20-M (Black)
51-MJ
5/16
27/64
1,600
7/32
871-22-M
51-MJ
5/8
7/16
2,300
1/4
871-23-F6
3-F6-950
11/16
21/32
3,500
5/16
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, if each specific type of cable is proof-tested ini­tially. Because of variation in rope strengths, grades, construction, and actual diameters, the test is necessary to insure proper selection of materials, the correct pressing procedure, and an adequate margin of safety for the intended use.
Figure 7-15. Typical terminal gauge.
Page 7-34
Par 7-148
9/8/98
AC 43.13-1B
7-149. CABLE SYSTEM INSPECTION.
Aircraft cable systems are subject to a variety of environmental conditions and deterioration. Wire or strand breakage is easy to visually rec­ognize. Other kinds of deterioration such as wear, corrosion, and/or distortion are not easily seen; therefore, control cables should be re­moved periodically for a more detailed inspec­tion.
a. At each annual or 100 hour inspec­tion, all control cables must be inspected for broken wires strands. Any cable assembly that has one broken wire strand located in a critical fatigue area must be replaced.
b. A critical fatigue area is defined as the working length of a cable where the cable runs over, under, or around a pulley, sleeve, or through a fair-lead; or any section where the cable is flexed, rubbed, or worked in any man­ner; or any point within 1 foot of a swaged-on fitting.
c. A swaged-on fitting can be an eye, fork, ball, ball and shank, ball and double shank, threaded stud, threaded stud and turn-buckle, compression sleeve, or any hardware used as a termination or end fitting on the ca­ble. These fittings may be attached by various swaging methods such as rotary swaging, roll swaging, hydraulic pressing, and hand swaging tools. (See MIL-T-781.) The pressures ex­erted on the fittings during the swaging proc­ess sometimes pinch the small wires in the ca­ble. This can cause premature failure of the pinched wires, resulting in broken wires.
d. Close inspection in these critical fa­tigue areas, must be made by passing a cloth over the area to snag on broken wires. This will clean the cable for a visual inspection, and detect broken wires if the cloth snags on the cable. Also, a very careful visual inspection
must be made since a broken wire will not al­ways protrude or stick out, but may lie in the strand and remain in the position of the helix as it was manufactured. Broken wires of this type may show up as a hairline crack in the wire. If a broken wire of this type is sus­pected, further inspection with a magnifying glass of 7 power or greater, is recommended. Figure 7-16 shows a cable with broken wires that was not detected by wiping, but was found during a visual inspection. The damage be­came readily apparent when the cable was re­moved and bent as shown in figure 7-16.
Figure 7-16. Cable inspection technique.
e. Kinking of wire cable can be avoided if properly handled and installed. Kinking is caused by the cable taking a spiral shape as the result of unnatural twist. One of the most common causes for this twist is improper un­reeling and uncoiling. In a kinked cable, strands and wires are out of position, which creates unequal tension and brings excessive wear at this part of the cable. Even though the kink may be straightened so that the damage appears to be slight, the relative adjustment between the strands has been disturbed so that the cable cannot give maximum service and should be replaced. Inspect cables for a popped core or loose strands. Replace any ca­ble that has a popped core or loose strands re­gardless of wear or broken wires.
Par 7-149
Page 7-35
AC 43.13-1B CHG 1
9/27/01
f. Nylon-jacketed cable with any cracks or necking down in the diameter of the jacket shall be replaced. Usable cable life is over when these conditions begin to appear in the nylon jacket.
g. External wear patterns will extend along the cable equal to the distance the cable moves at that location and may occur on one side of the cable or on its entire circumference. Replace flexible and nonflexible cables when the individual wires in each strand appear to blend together (outer wires worn 40 to 50 per­cent) as depicted in figure 7-17. Actual in­stances of cable wear beyond the recom­mended replacement point are shown in fig­ure 7-18.
h. 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 7-19) is not easily detected unless the strands of the ca­ble are separated. This type of wear is a result of the relative motion between inner wire sur­faces. Under certain conditions, the rate of this type of wear can be greater than that occurring on the surface.
Figure 7-18. Worn cable (replacement necessary).
i. Areas especially conducive to cable corrosion are battery compartments, lavatories, wheel wells, etc.; where a concentration of corrosive fumes, vapors, and liquids can ac­cumulate. Carefully examine any cable for corrosion, when it has a broken wire in a sec­tion that is not in contact with a wear-producing airframe component, such as a pul­ley, fair-lead, etc. If the surface of the cable is corroded, relieve cable tension and carefully force the cable open by reverse twisting and visually inspect the interior. 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 rust and corrosion with a clean, dry, coarse-weave rag, or fiber brush. Do not use metallic
C737822C
(NOTE BLENDING OF WORN AREAS)
(WORN AREAS INDIVIDUALLY DISTINGUISHABLE)
Figure 7-17. Cable wear patterns.
Page 7-36
Par 7-149
9/27/01
AC 43.13-1B CHG 1
actuate the controls and check for friction or hard movement. These are indications that ex­cessive cable tension exists.
NOTE: If the control movement is stiff after maintenance is performed on con­trol surfaces, check for parallel cables twisted around each other, or cables connected in reverse.
k. Check swaged terminal reference marks for an indication of cable slippage within the fitting. Inspect the fitting assembly for distortion and/or broken strands at the ter­minal. Ensure that all bearings and swivel fit­tings (bolted or pinned) pivot freely to prevent binding and subsequent failure. Check turn-buckles for proper thread exposure and broken or missing safety wires/clips.
l. Inspect pulleys for roughness, sharp edges, and presence of foreign material em­bedded in the grooves. Examine pulley bear­ings to ensure proper lubrication, smooth rota­tion; and freedom from flat spots, dirt, and paint spray. During the inspection, rotate the pulleys, which only turn through a small arc, to provide a new bearing surface for the cable. Maintain pulley alignment to prevent the cable from riding on the flanges and chafing against guards, covers, or adjacent structure. Check all pulley brackets and guards for damage, alignment, and security.
m. Various cable system malfunctions
may be detected by analyzing pulley condi­tions. These include such discrepancies as too much tension, misalignment, pulley bearing problems, and size mismatches between cables and pulleys. Examples of these condition are shown in figure 7-20.
Figure 7-19. Internal end view of cable wear.
wool or solvents to clean installed cables. Use of metallic wool will embed dissimilar metal particles in the cables and create further corro­sion problems. Solvents will remove internal cable lubricant allowing cable strands to abrade and further corrode. After thorough cleaning, sparingly apply specification MIL-C-16173, grade 4, corrosion-preventive compound to cable. Do not apply the material so thick that it will interfere with the operation of cables at fair-leads, pulleys, or grooved bellcrank areas.
j. Examine cable runs for incorrect rout­ing, fraying, twisting, or wear at fair-leads, pulleys, antiabrasion strips, and guards. Look for interference with adjacent structure, equipment, wiring, plumbing, and other con­trols. Inspect cable systems for binding, full travel, and security of attaching hardware. Check for slack in the cable system by at­tempting to move the control column and/or pedals while the gust locks are installed on the control surfaces. With the gust locks removed,
Par 7-149
Page 7-37
AC 43.13-1B
9/8/98
Figure 7-20. Pulley wear patterns.
n. Inspect fair-leads for wear, breakage, alignment, cleanliness, and security. Examine cable routing at fair-leads to ensure that defec­tion angles are no greater than 3°€maximum. Determine that all guides and anti-abrasion strips are secure and in good condition.
o. Examine pressure seals for wear and/or material deterioration. Seal guards should be positioned to prevent jamming of a pulley in case pressure seal fails and pieces slide along the cable.
7-150. CORROSION AND RUST PRE­VENTION. To ensure a satisfactory service life for aircraft control cables, use a cable lu­bricant to reduce internal friction and prevent corrosion.
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 that corrosion-resistant steel cable does not require this treatment for rust prevention.
b. Lubrication and corrosion preventive treatment of carbon steel cables may be ef­fected simultaneously by application of com­pound MIL-C-16173, grade 4, or
MIL-C-11796, Class I. MIL-C-16173 com­pound should be brushed, sprayed, or wiped on the cable to the extent it penetrates into the strands and adequately covers the cable sur­faces. It will dry "tack free" in 24 hours at 77 °F. MIL-C-11796 compound is applied by dipping the cable for 1/2 minute into a tank of compound heated to 77 ° ± 5 °C (170 ° ± 9 °F) for 1/2 minute then removing it and wiping off the excess oil. (An example of cable corro­sion, attributable to battery acid, is shown in
figure 7-21.)
Page 7-38
Par 7-149
9/27/01
AC 43.13-1B CHG 1
7-152. CABLE MAINTENANCE. Fre­quent inspections and preservation measures such as rust-prevention treatments for bare carbon steel cable areas, will help to extend cable service life. Where cables pass through fair-leads, 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 grease or general-purpose, low-temperature oil.
Figure 7-21. Corrosion.
7-151. WIRE SPLICES. Standard manu­facturing splices have been mistaken for de­fects in the cable because individual wire end splices were visible after assembly of a fin­ished cable length. In some instances, the pro­cess of twisting outer strands around the core strand may also slightly flatten individual outer wires, particularly in the area of a wire splice. This flattening is the result of die-sizing the cable, and does not affect the strength of the cable. These conditions (as shown in fig­ure 7-22) are normal, and are not a cause for cable rejection.
7-153. CABLE TENSION ADJUST­MENT. Carefully adjust, control cable tension in accordance with the airframe manufacturer's recommendations. On large aircraft, take the temperature of the immediate area into consid­eration when using a tension meter. For long cable sections, use the average of two or three temperature readings to obtain accurate tension values. If necessary, compensate for extreme surface temperature variations that may be en­countered if the aircraft is operated primarily in unusual geographic or climatic conditions such as arctic, arid, or tropic locations. Use rigging pins and gust locks, as necessary, to en­sure satisfactory results. At the completion of rigging operations, check turnbuckle adjustment and safetying in accordance with section 10 of this chapter.
7-154.—7-164. [RESERVED.]
Figure 7-22. Manufacturer's wire splice.
Par 7-151
Page 7-39 (and 7-40)
9/8/98
AC 43.13-1B
SECTION 9. TURNBUCKLES
7-165. GENERAL. A turnbuckle is a de­vice used in cable systems to provide a means of adjusting tension. Turnbuckles have barrel-shaped sleeves with internal left- and right-hand threads at opposite ends. The cables, with terminals attached, are made to such a length that, when the turnbuckle is adjusted to give the specified cable tension, a sufficient number of threads on the terminal ends are screwed into the barrel to hold the load. The clip-locking turnbuckle and its associated parts are identical to standard AN and MS parts ex­cept for a slot grooved on the interior of the barrel and the shanks of the forks, eyes, etc. The clip-locking turnbuckle parts have the following drawing numbers: MS21251, turn-buckle body; MS21252, turnbuckle clevis end; MS21253, turnbuckle clevis end (for bearing); NAS649 and NAS651, turnbuckle clip; MS21254 and NAS648, turnbuckle eye (for pin); MS21255 and NAS647, turnbuckle eye end (for wire rope); NAS645 and NAS646, turnbuckle fork; MS21256, turnbuckle barrel locking clip; AN130-170, turnbuckle assem­blies; and, MS21259 and MS21260, terminal, wire rope, stud.
NOTE: Turnbuckles showing signs of thread distortion/bending should be replaced. Turnbuckle ends are de­signed for providing the specified ca­ble tension on a cable system, and a bent turnbuckle would place undesir­able stress on the cable, impairing the function of the turnbuckle.
7-166. TURNBUCKLE INSTALLATION.
(See figure 7-25.) When installing cable sys­tem turnbuckles, it is necessary to screw both threaded terminals into the turnbuckle barrel an equal amount. It is essential that turnbuckle terminals be screwed into the barrel so that not more than three threads on the terminal are ex­posed. (See figure 7-23A.) On initial installa­tion, the turnbuckle terminals should not be screwed inside the turnbuckle barrel more than four threads. (See figure 7-23B.)
TOTAL TOLERANCE SEVEN THREADS EACH
Figure 7-25. Turnbuckle thread tolerance.
7-167. WITNESS HOLE. Some manufac­turers of turnbuckles incorporate a "witness hole," in the turnbuckle barrel to ensure that the threaded cable terminals are screwed in far enough into the barrel. The "witness hole" can be inspected visually, or by using a piece of safety wire as a probe.
7-168.—7-178. [RESERVED.]
Par 7-165
Page 7-41 (and 7-42)
9/8/98
AC 43.13-1B
SECTION 10. SAFETY METHODS FOR TURNBUCKLES
7-179. GENERAL. Safety all turnbuckles with safety wire using either the double or sin­gle-wrap method, or with any appropriately approved special safetying device complying with the requirements of FAA Technical Stan­dard Order TSO-C21. The swaged and un-swaged turnbuckle assemblies are covered by AN standard drawings. Do not reuse safety wire. Adjust the turnbuckle to the correct ca­ble tension so that no more than three cable threads are exposed on either side of the turn-buckle barrel.
7-180. DOUBLE-WRAP METHOD. Of
the methods using safety wire for safetying turnbuckles, the method described here is pre­ferred, although either of the other methods described is satisfactory. The method of dou­ble-wrap safetying is shown in figure 7-26(A).
a. Use two separate lengths of wire. Run one end of the wire through the hole in the bar­rel of the turnbuckle and bend the ends of the wire toward opposite ends of the turnbuckle.
b. Pass the second length of the wire into the hole in the barrel and bend the ends along the barrel on the side opposite the first. Spiral the two wires in opposite directions around the barrel to cross each other twice between the center hole and the ends.
c. Then pass the wires at the end of the
turnbuckle in opposite directions through the hole in the turnbuckle eyes or between the jaws of the turnbuckle fork, as applicable, laying one wire along the barrel and wrapping the other at least four times around the shank of the turnbuckle and binding the laid wires in place before cutting the wrapped wire off.
d. Wrap the remaining length of safety wire at least four turns around the shank and cut it off. Repeat the procedure at the opposite end of the turnbuckle.
e. When a swaged terminal is being safetied, pass the ends of both wires through the hole provided in the terminal for this pur­pose and wrap both ends around the shank as previously described. If the hole is not large enough to allow passage of both wires, pass the wire through the hole and loop it over the free end of the other wire, and then wrap both ends around the shank as previously described. Another satisfactory double-wrap method is similar to the previous method, except that the spiraling of the wires is omitted as shown in
figure 7-26(B).
7-181. SINGLE-WRAP METHOD. The
single-wrap methods described in the follow­ing paragraphs and as illustrated in figure 7-26(C) and (D) are acceptable, but are not the equal of the double-wrap methods.
a. Pass a single length of wire through the cable eye or fork, or through the hole in the swaged terminal at either end of the turnbuckle assembly. Spiral each of the wire ends in op­posite directions around the first half of the turnbuckle barrel, so as to cross each other twice. Thread both wire ends through the hole in the middle of the barrel so that the third crossing of wire ends is in the hole, again, spi­ral the two wire ends in opposite directions around the remaining half of the turnbuckle, crossing them twice. Then, pass one wire end through the cable eye or fork, or through the hole in the swaged terminals, in the manner previously described. Wrap both wire ends around the shank for at least four turns each, cutting off excess wire. This method is shown
in figure 7-26(C).
Par 7-179
Page 7-43
AC 43.13-1B
9/8/98
b. For the method shown in figure
7-26D, pass one length of wire through the center hole of the turnbuckle and bend the wire ends toward opposite ends of the turnbuckle. Then pass each wire end through the cable eye or fork, or through the hole in the swaged ter­minal, and wrap each wire around the shank for at least four turns, cutting off excess wire. After safetying, no more than three threads of the turnbuckle threaded terminal should be ex­posed.
7-182. SAFETY-WIRE SECURED TURNBUCKLES. (See figure 7-27.) Before
securing turnbuckles, threaded terminals
should be screwed into the turnbuckle barrel until no more than three threads of either ter­minal are outside the barrel. After the turn-buckle has been adjusted for proper cable ten­sion, two pieces of safety wire are inserted, half the wire length into the hole in the center of the turnbuckle barrel. The safety-wires are bent so that each wire extends half the length of the turnbuckle on top and half on bottom. The ends of the wires are passed through the hole in the turnbuckle eyes or between the jaws of the turnbuckle fork, as applicable. The wires are then bent toward the center of the turnbuckle and each wire is wrapped around
Page 7-44
Par 7-181
9/8/98
AC 43.13-1B
the shank four times, binding the wrapping wires in place as shown in figure 7-27.
a. When a swaged terminal is being se­cured, one wire is passed through the hole in the terminal and is looped over the free end of the other wire and both ends wrapped around the shank. All lock wire used in the safetying of turnbuckles should be carbon steel, corro­sion-resistant steel, nickel-chromium iron alloy (inconel), nickel-copper alloy (monel) or alu­minum alloy. For safety cable diameter of safety wire size and material, refer to table 7-8.
b. Care should be exercised when safety wiring, particularly where corrosion will pres­ent a problem, because smaller wire sizes tend to crack when twisted.
7-183. SPECIAL LOCKING DEVICES.
Several turnbuckle locking devices are avail­able for securing turnbuckle barrels such as wire-locking clips. Persons intending to use a special device must ensure the turnbuckle as­sembly has been designed to accommodate such devices. A typical unit is shown in fig­ure 7-28. When special locking devices are not readily available, the use of safety wire is acceptable.
7-184. ASSEMBLING AND SECURING CLIP-LOCKING TURNBUCKLES. (See table 7-9 and figure 7-29.) Wire clip-locking turnbuckles are assembled and secured in the following ways.
a. Engage threads of turnbuckle barrel with threads of cable terminal and turn barrel until proper cable tension is reached.
b. Align slot in barrel with slot in cable terminal.
c. Hold lock clip between thumb and forefinger at loop end and insert straight end of clip into opening formed by aligned slots.
d. Bring hook end of lock clip over hole in center of turnbuckle barrel and seat hook loop into hole.
e. Apply pressure to hook shoulder to en­gage hook lip in turnbuckle barrel and to com­plete safety locking of one end of turnbuckle.
NOTE: Repeat the above steps to safety lock the opposite end of turn-buckle. Both lock clips may be in­serted in the same turnbuckle barrel hole or they may be inserted in oppo­site holes. However, do not reverse wire locking clips
Table 7-8. Turnbuckle safetying guide.
Cable Size
Type of Wrap
Diameter of Safety Wire
Material (An­nealed
Condition)
1/16
Single
0.040
Copper, brass.1
3/32
Single
0.040
Copper, brass.1
1/8
Single
0.040
Stainless steel, Monel and
"K" Monel.
1/8
Double
0.040
Copper, brass.1
1/8
Single
0.057 min.
Copper, brass.1
5/32 and
greater.
Double
0.040
Stainless steel, Monel and
"K" Monel.1
5/32 and greater
Single
0.057 min.
Stainless steel, Monel or
"K" Monel.1
5/32
and greater
Double
0.0512
Copper, brass.
1Galvanized or tinned steel, or soft iron wires are also accept­able.
Par 7-182
Page 7-45
AC 43.13-1B
9/8/98
Figure 7-27. Securing turnbuckles.
Figure 7-28. Clip-type locking device.
Page 7-46
Par 7-184
9/8/98
AC 43.13-1B
Table 7-9. Locking-clip application.
NOMINAL CABLE DIA.
THREAD UNF-3
LOCKING
CLIP MS21256
TURNBUCKLE
BODY MS21251
1/16
No. 6-40
-1
-2S
3/32
No. 10-32
-3S
-2
-3L
1/8
1/4-28
-1
-4S
-2
-4L
5/32
-1
-5S
-2
-5L
3/16
5/16-24
-1
-6S
-2
-6L
7/32
3/8-24
-7L
1/4
-8L
9/32
7/16-20
-3
-9L
5/16
1/2-20
-10L
FIGURE 7-27. Assembling and securing clip-locking turnbuckles 7-185.—7-195. [RESERVED.]
Par 7-184
Page 7-47 (and 7-48)
9/8/98
AC 43.13-1B
SECTION 11. HARDWARE IDENTIFICATION TABLES
Table 7-10. TABLE OF RIVETS.
Table 7-10. (CONTINUED)
I Rivet Number
Description_
Rivet, 100-csk. Head steel, monel, copper
Rivet Number Description
NAS 1738-1739
Rivet, blind, protruding & flush hd., mech. locked spindle, bulbed
NAS1806-1816
Rivet, hi-shear, flathead., ti. alloy
NAS1906-1916
0LZ2
Rivet, hi-shear, 100° hd., ti. alloy
AN124951-125550
Rivet, solid universal head & 100° csk. head, cres. steel, inconel
AN125551-1255700
rj
Rivet, solid universal head, steel
AN426 MS20426
Rivet, solid, csk. 100° head al. alloy
AN470 MS20470
c=40
Rivet, solid, universal head, al. & al. alloy
MS9319
Rivet,
solid univ. head, AMS 7233
MS9403
Rivet, solid, universal head, AMS 5737
MS16535
Rivet, tubular, oval head
AN427
AN430
Rivet,
round head al. Alloy
AN441
Rivet, tinners Head, steel, ss, monel
AN456
Rivet, brazier head, aluminum alloy
AN123151-123750 NAS 1200
Rivet, universal head & 100- steel, Inconel
Rivet, solid, 100- flush shear head
NAS 1241
Rivet, solid, 100- flush head
NAS 1242
Rivet, solid universal
NAS 1398
head
Rivet, blind, protruding head, locked spindle
NAS 1399
Rivet, blind, 100- csk. Head, locked spindle
Par 7-196
Page 7-49
AC 43.13-1B
Table 7-10. (CONTINUED)
Table 7-10. (CONTINUED)
9/8/98
MS16536
I
Rivet, tubular, 100° flat csk. head
MS20426
TT00
Rivet, solid, csk., 100° al. alloy
MS20427
Rivet, solid, csk.,
100° flush hd.,
AMS 7233
MS20470
Rivet, solid, universal head, al. alloy
MS20600
Rivet, blind, pull stem, protruding head
MS20601
Rivet, blind, pull stem, 100°, flush head
MS20602-20603
Rivet, blind, explosive
MS20604-20605 A--T|-i.............1
Rivet, blind nonstruc-tural univ.
and 100° flush head
MS20613-20615
Rivet, solid, monel, universal hd., steel, ss, brass, copper
NAS452-453
Rivnut, 100° csk. head & flathead
NAS454-455
trap l-:^n
Rivet
blind, al. alloy
NAS508
Rivet,
universal head, monel
NAS1054
Rivet, hi-shear, protruding head
NAS1055
c. 1
Rivet, hi-shear, 100° flush head
NAS1097
IT
Rivet, solid, 100° flush shear head, al. Alloy
NAS1198
Rivet, solid, universal head
NAS1199
Rivet, solid, 100° flush head
Table 7-11. TABLE OF SCREWS.
Screw MS, AN, or NAS Number
Description
AN255
Screw,
external relieved body
AN500 & 501
iiill^i
Screw,
machine fillister head
AN502 & 503
Screw,
machine, fill. Head, drilled, coarse & fine
AN504
atmmi\if£j
Screw, tapping, thread cutting rnd. Head, mach. Thread
Page 7-50
Par 7-196
9/8/98
AC 43.13-1B
Table 7-11. (CONTINUED)
Table 7-11. (CONTINUED)
Screw MS, AN, or NAS Number
Description
AN505
Screw, machine, flathead,
82° coarse thread
AN506
Screw, tapping, type F, coarse & fine
AN507
Screw, machine, flathead, 100°
AN508
Screw, machine, round head
AN509
Screw machine, 100° structural
AN510
Screw, machine,
flathead,
82° fine thread
AN515 & AN520
Screw, machine, round head
AN525
ik
Screw, washer head
AN526
Screw,
machine buttonhead
AN530
Screw-tapping, thread cutting, rnd. hd.
AN531
Screw, tapping, thread forming or cut­ting, 82° flathead.
Par 7-196
Screw MS, AN, or NAS Number
Description
Drive screw, round head
AN545
Screw, wood, round head
AN550
Screw, wood,
flathead, 82°
AN565
Setscrew,
hex. & fluted socket
AN115401-115600
Screws,
flat fill. head,
steel, .190-.375
AN115601-115800
wmmQ
Drilled shank Screw flat fill. head, steel, .190-.375
AN115801-116150
Screw,
flat fill. head,
steel. .190-.375
AN116901-117080
fillip
Screw,
oval fill. head, steel
MS9016
©
Bushing Screw, plain
MS9017
Bushing Screw, slotted
MS9122-9123
Screw,
machine slotted hex. hd.
Page 7-51
AC 43.13-1B
9/8/98
Table 7-11. (CONTINUED)
Table 7-11. (CONTINUED)
Screw MS, AN, or NAS Number
Description
MS9177-9178
Screw,
dbl. hex. head, cres.
MS9183-9186
Screw, machine, steel, drilled 12 pt. hd., cad. plate
MS9187-9188
OT-flg(§j)
Screw,
drilled dbl. hex. head, cres.
MS9189-9192
Screw, machine, steel, 12 pt. hd., black oxide
MS9206-9214
Screw,
dbl. hex. ext. washer head, diffused nickel cad. plate
MS9215-9223
Screw, dbl. hex. ext. washer head, diffused nickel cad. plate, drilled
MS9281-9291
Screw, machine, hex. hd., AMS 6322 black oxide
MS9292-9302
■n_QO
Screw, machine,
hex. hd., AMS 6322
blk. oxide, drilled
MS9316-9317
Screw, machine, steel slotted hex. head
MS9438-9439
Screw, mach. steel
AMS 6304 diffused
nickel cad. hex. hd., one hole
MS9631-9639
Screw, mach., hex. hd. one hole, full shank, titanium AMS 4967
Screw MS, AN, or NAS Number
Description
MS16198
Screw, wood, slotted RH austenitic corr. res. steel
MS16199
Screw, wood, slot flat-head, copper silicone
MS16995
Screw, cap, socket head hex., corr. resist­ing steel UNC-3A
MS16996
Screw, cap, socket head, hex., corr. re­sisting steel UNF-3A
MS16997
Screw, cap, socket head, hex., alloy steed cad. UNC-3A
MS16998
Screw, cap, socket head, hex., alloy steel, cad. UNF-3A
MS18063-18068
HI©
Setscrew, self-locking, cup, flat, cone pts., steel & stainless
MS18211
Screw, machine, flat-head, plastic, nylon
MS18212
Screw, machine, pan-head, plastic, nylon
MS21090
Screw, self-lock, pan-head, cross recessed
MS21207
(J)
Screw, tapping, 100° clk. flathead., steel, cres. steel
Page 7-52
Par 7-196
9/8/98
AC 43.13-1B
Table 7-11. (CONTINUED)
Table 7-11. (CONTINUED)
Screw MS, AN, or NAS Number
Description
Screw MS, AN, or NAS Number
Description
MS24673-24678
Screw, cap socket hd.,
flat, drilled
MS24693
Screw, machine, flat csk. head, 100° cross recess
MS24694
Screw, machine, csk. flathead., 100° cross recess, structural
MS27039
flisamii.cQ (<>)
Screw, machine, panhead, structural, cross recessed
MS35190-35203
OWIH(J(«J)
Screw, machine 82° flathead., cross re­cessed, steel, brass, alum.
MS35206-35219
Screw, machine, pan-head, cross recessed, steel, brass, alum.
MS35223-35234
$SSSES2i|^
Screw, machine, pan-head, slotted, SS steel, steel
MS35239-35243
Screw, machine, flat-head., slotted, steel
MS35265-35278
Screw, machine, drilled fillister head, slotted, SS steel, brass, alum.
MS35492-35493
Screw, wood, flathead, cross recessed
MS35494-35495
Screw. wood, flat & round hd., slotted
MS21262
Screw, self-lock, int. wrenching
MS21277-21285 MS21286-21294
Screw, machine, dou­ble hex., ext. washer head
Screw, machine, dou­ble hex., ext. washer head
MS21295
Screw, self-lock, int. wrenching
ir-Ulliiii'
It*!*!**!-1
MS21318
Screw, drive, round head, Type U
MS21342
Setscrew, fluted socket, cup and flat point
MS24615-24618
Screw, tapping, phillips recessed, pan & 82° flathead Type A
MS24619-24622
Screw, tapping, phillips recessed, pan & 82° flathead Type B
©
MS24623-24626
Screw, tapping, cross recessed pan & 82° flathead, Type BF or
BT
MS24627-24630
Screw, tapping, thread cutting cross recessed pan & 82° flathead, Type F
MS24667 & 24671
Screw, cap socket hd.,
flat, csk.
Par 7-196
Page 7-53
AC 43.13-1B
9/8/98
Table 7-11. (CONTINUED)
Table 7-11. (CONTINUED)
Screw MS, AN, or NAS Number
Description
MS35914
Insert, screw, thread, self-tapping
MS51017-51047
Hi®
Setscrew, hex. socket SS & steel half dog, cone, flat, cup pt.
MS51861
Screw, tapping, type AB, panhead, cross re­cessed
MS51862
-eating
Screw, tapping, type AB, flathead., cross re­cessed
MS51957-51958
Screw, machine, pan-head, cross recessed
MS51959-51960
Screw, machine, flat-head, cross recessed
MS51963-51966
Setscrew, hex. socket, cup & flat point
MS51973-51974
4111©
Setscrew, hex. socket, cone point
MS51975
Screw, shoulder, socket head
MS51976-51977
«■©
Setscrew, hex. socket, half dog point
MS51981-51982
•111©
Setscrew, hex. socket, oval point
Screw MS, AN, or NAS Number
Description
NAS220-237
Screw, brazier hd. phil­lips recessed
NAS384-385
Screw, oval head, phil­lips recessed 100°, 82°, steel
NAS387-388
Screw, machine, oval hd., 100°, 82°, steel
NAS514
Screw, machine, 100° flathead., fully threaded, al. steel
NAS517
Screw, 100° flathead, close tol. 160,000 psi
NAS548
fflSSSET D f m i
wBmII VtJ
Screw, 100° flathead, type B tapping
NAS560
Screw, machine, 100° structural, hi-temp
NAS600-606
Screw, machine, air­craft, panhead phillips recessed, full thr., steel
NAS608-609
Screw, hex. socket cap, plain & self-locking, drilled head
NAS623
Screw, panhead. thr. short, 160,000 psi
NAS720
Screw, panhead, as­sembled
Page 7-54
Par 7-196
9/8/98
AC 43.13-1B
Table 7-11. (CONTINUED)
Table 7-11. (CONTINUED)
Screw MS, AN, or NAS Number
Description
NAS1081
Setscrew, hex. socket, self-locking
NAS1096
Screw, hex. head, re­cess, full thr.
NAS1100
■HQ®
Screw, machine, panhead, full thread, torq.-set
NAS1101
hbO©
Screw, machine,
flat fill hd. full thread
NAS1102
Screw, machine, 100° flathead. full thr. torq.-set
NAS1121-1128
Screw, machine, flat fill hd., short thread, torq.-set
NAS1131-1138
Screw, machine, pan hd., short thread, torq.-set
NAS1141-1148
Screw, machine, panhead. modified, short thread torq.-set
NAS1151-1158
mm f]rg\
Screw, machine,
100° flathead.,
sort thread, torq.-set
NAS1161-1168
ma zfl®
Screw, machine,
100° flathead.,
shear, torq.-set
NAS1171-1178
Screw, panhead., shear, self-lock., torq.-set
Screw MS, AN, or NAS Number
Description
NAS1181-1188
Screw, flat fill hd.,
self-locking,
torq.-set
NAS1189
Screw, flat 100° hd., full thread, self-locking
NAS1190
Screw, panhead., self-locking, full thread
NAS1191
Screw, flat fill. hd., full thread, self-locking
NAS1216
Screw, panhead hi-torque, full thread
NAS1217
BUI "Q^IP
Screw, panhead, hi-torque, short thread
NAS1218
Screw, panhead, hi-torque, short thread
NAS1219
Screw, 100° csk. hd., hi-torque, full thread
NAS1220
m—
Screw, 100° csk. hd., hi-torque, short thread
NAS1221
Screw, 100° clk. hd., hi-torque, long thread
NAS1298
Screw, shoulder, brazier head
Par 7-196
Page 7-55
AC 43.13-1B Table 7-11. (CONTINUED)
Table 7-11. (CONTINUED)
9/8/98
Screw MS, AN, or NAS Number
Description
Screw MS, AN, or NAS Number
Description
NAS5000-5006
Screw, panhead, tri-wing recess, short thr., alloy stl.
NAS5100-5106
Screw, panhead, tri-wing recess, short thr., cres.
NAS5200-5206
Screw, panhead, tri-wing recess, short thr., cres.
NAS5300-5306
Screw, fillister head, tri-wing recess, full thr., alloy stl.
NAS5400-5406
Screw, fillister hd., tri-wing recess, full thr., cres.
NAS5500-5506
Screw, fillister hd., tri-wing recess, full thr., titanium
NAS5600-5606
Screw, 100° head, tri-wing recess, full thr., alloy stl.
NAS5700-5706
^jjmmin^ (^)
Screw, 100° head, tri-wing recess, full thr., cres.
NAS5800-5806
Screw, 100° head, tri-wing recess, full thr., titanium
NAS5900-5903
Screw, hex. Head, tri-wing recess, full thr., alloy stl.
NAS6000-6003
Screw, hex. Head, tri-wing recess, full thr., cres.
NASI 299
ffifflL_J(l
Screw, shoulder, 100° flathead
NAS1300
Thumbscrew, drilled/undrilled
NASI 301
Screw, panhead, as­sembled washers phil­lips recess
NAS1351-1352
Socket Capscrew, hex. head, drilled/undrilled
NAS1393
Screw, 82° flathead, torq-set
NAS1402-1406
Screw, panhead, phil-
NASI 579
lips recess
Screw, panhead., full thread, 1200° F
NAS1603-1610 | Screw, flush head,
.0312 O.S.
NAS1620-1628
=3©
Screw, machine, 100° flat short thread, torq-set
NAS1630-1634 NAS1635
Screw, machine, panhead., short thread, torq.-set
Screw, panhead cross recessed, full thread
tiitlituuHi»n'
Page 7-56
Par 7-196
9/8/98
AC 43.13-1B