Control Cables and Safetying Methods

7-73 Acres Sleeve Type Basic Part Number JK5610 JK5511 JK5512 JK5516 JK5517 JK5533 100° 509 tension head plus flange Protruding head (shear) 100° Low profile head 100° Standard profile head (509 type) Protruding head (tension) 100° Oversize tension head (1⁄64 oversize bolt) 2 Sleeve Part Number Bolt Size Sleeve Length 8 10 12 16 1⁄8 #6 5⁄32 #8 #10 ¼ 5⁄16 3⁄8 JK5511( )04( )( ) JK5512( )04( )( ) JK5516( )04( )( ) JK5517( )04( )( ) JK5511( )45( )( ) JK5512 JK5516( )45( )( ) JK5517( )45( )( ) JK5511( )05( )( ) JK5512( )05( )( ) JK5516( )05( )( ) JK5517( )05( )( ) JK5511( )55( )( ) JK5512( )55( )( ) JK5516( )55( )( ) JK5517( )55( )( ) JK5610( )55( )( ) JK5511( )06( )( ) JK5512( )06( )( ) JK5516( )06( )( ) JK5517( )06( )( ) JK5610( )06( )( ) JK5511( )08( )( ) JK5512( )08( )( ) JK5516( )08( )( ) JK5517( )08( )( ) JK5610( )08( )( ) JK5511( )10( )( ) JK5512( )10( )( ) JK5516( )10( )( ) JK5517( )10( )( ) JK5610( )10( )( ) JK5511( )12( )( ) JK5512( )12( )( ) JK5516( )12( )( ) JK5517( )12( )( ) JK5610( )12( )( ) Sleeve Part Number Bolt Size Sleeve Length Acres Sleeve for 1⁄64 Oversize Bolt JK5533( )06( )( ) JK5533( )08( )( ) JK5533( )10( )( ) JK5533( )12( )( ) 13⁄64 17⁄64 21⁄64 25⁄64 12 16 21 NOTES: Acres sleeve, JK5533 1⁄64 oversize available in A286 ste el only Acres sleeve length in sixteenth-inch increments 1 2 Material Material Code 5052 Aluminum alloy ½ hard 6061 Aluminum alloy (T6 condition) A286 Stainless steel (passivate) C B A Part Number Breakdown JK5511 A 04 N 08 L JK5511 A 04 N 08 L Basic part number Material code 1 Fastener s hank diameter in 32nds Surface finish N = No finish C = C hemical film per MIL-C -554 Length in sixteenth inch increments (Required installation length by breaking off at proper groove) “L” at end of part number indicates cetyl alcohol lubricant 7-74 Diameter 7 strands, 7 wires to each strand 7 strands, 19 wires to each strand A. Drill out corrosion or damage to existing hole to 1/64 oversize.

B. Select proper type and length acres sleeve for existing fastener. C. Bond sleeve in structure hole with MIL-S-8802 class A ½ sealant. Installation Procedure 1/8 #6 5/32 #8 #10 ¼ 5/16 3/8 9/64 23 11/64 15 5 14 21/64 25/64 0.1406 0.1540 0.1719 0.1800 0.2055 0.2660 0.3281 0.3908 28 24 18 16 6 17/64 0.1405 0.1520 0.1695 0.1770 0.2040 0.2656 Bolt Size Standard Fit Close Fit Drill Number Drill Diameter Drill Number Drill Diameter Hole Preparation 7/32 9/32 11/32 13/32 13/64 17/64 21/64 25/64 0.2187 0.2812 0.3437 0.4062 Bolt Size Drill N umber Drill Diameter Hole Preparation for 1⁄64 Oversize Bolt Existing fastener Acres sleeve Structure1/64 Oversize hole Acres sleeve installation 1/8 — 3/8 diameter 7 x 19 1/16 — 3/32 diameter 7 x 7 7-75 MS20663 Double shank ball end terminal MS20664 Single shank ball end terminal AN665 Rod end terminal AN666 Threaded cable terminal MS20667 Fork end cable terminal AN668/MS20668 Eye end cable terminal Pin eyeSwaged terminal Barrel Length (threads flush with ends of barrel)

Safetying Methods

To ensure fasteners do not separate from their nuts or holding ends, various safetying methods are used in aircraft from heavy aircraft to gliders to recreational aircraft. Safetying is the process of securing all aircraft, bolts, nuts, screws, pins, and other fasteners so that they do not work loose due to vibration. A familiarity with the various methods and means of safetying equipment on an aircraft is necessary to perform maintenance and inspection. There are various methods of safetying aircraft parts. The most widely used methods are safety wire, cotter pins, lock washers, snap rings, and special nuts, such as self-locking nuts, pal nuts, and jam nuts. Some of these nuts and washers have been previously described in this chapter.

Pins The three main types of pins used in aircraft structures are the taper pin, flathead pin, and cotter pin. Pins are used in shear applications and for safetying. Roll pins are finding increasing uses in aircraft construction. Taper Pins Plain and threaded taper pins (AN385 and AN386) are used in joints that carry shear loads and where absence of play is essential. The plain taper pin is drilled and usually safetied with wire. The threaded taper pin is used with a taper pin washer (AN975) and shear nut (safetied with a cotter pin or safety clip) or self-locking nut. Flathead Pin Commonly called a Clevis pin, the flathead pin (MS20392) is used with tie rod terminals and in secondary controls, which are not subject to continuous operation. The pin is customarily installed with the head up so that if the cotter pin fails or works out, the pin remains in place.

Cotter Pins The AN380 cadmium-plated, low-carbon steel cotter pin is used for safetying bolts, screws, nuts, other pins, and in various applications where such safetying is necessary. The AN381 corrosion-resistant steel cotter pin is used in locations where nonmagnetic material is required or in locations where resistance to corrosion is desired. Roll Pins The roll pin is a pressed fit pin with chamfered ends. It is 7-76 Clevis, rod end, adjustable Tube, steel, or aluminum alloy Self-aligning, anti-friction rod end assembly, adjustable Check nut Rod end, threaded 1 2 3 4 5 876 NOTE: The safety wire is shown installed for right-hand threads. The safety wire is routed in the opposite direction for left-hand threads.

Valves Oil caps Drain cocks 7-77 AN standard fillister head screw (drilled head) Bulkhead AN3102 receptacle AN3057 adapterAN3106 plug tubular in shape and is slotted the full length of the tube. The pin is inserted with hand tools and is compressed as it is driven into place. Pressure exerted by the roll pin against the hole-walls keeps it in place until deliberately removed with a drift punch or pin punch.

Safety Wiring

Safety wiring is the most positive and satisfactory method of safetying cap screws, studs, nuts, bolt heads, and turnbuckle barrels, which cannot be safetied by any other practical means. It is a method of wiring together two or more units in such a manner that any tendency of one to loosen is counteracted by the tightening of the wire. Nuts, Bolts, & Screws Nuts, bolts, and screws are safety wired by the single wire or double twist method. The double twist method is the most common method of safety wiring. The single wire method may be used on small screws in a closely spaced closed geometrical pattern, on parts in electrical systems, and in places that are extremely difficult to reach. Safety wiring should always be per conventional methods or as required by the manufacturer, especially for Light Sport Aircraft (LSA).

commonly used in safety wiring nuts, bolts, and screws. Careful study of Figure 7-72 shows that: • Examples 1, 2, and 5 illustrate the proper method of safety wiring bolts, screws, square-head plugs, and similar parts when wired in pairs. • Example 3 illustrates several components wired in series. • Example 4 illustrates the proper method of wiring castellated nuts and studs. (Note that there is no loop around the nut.) • Examples 6 and 7 illustrate a single-threaded component wired to a housing or lug. • Example 8 illustrates several components in a closely spaced closed geometrical pattern using a single wire method.

When drilled head bolts, screws, or other parts are grouped together, they are more conveniently safety wired to each other in a series rather than individually. The number of nuts, bolts, or screws that may be safety wired together is dependent on the application. For instance, when safety wiring widely spaced bolts by the double twist method, a group of three should be the maximum number in a series. When safety wiring closely spaced bolts, the number that can be safety wired by a 24-inch length of wire is the maximum in a series. The wire is arranged so that if the bolt or screw begins to loosen, the force applied to the wire is in the tightening direction.

Parts being safety wired should be torqued to recommend values and the holes aligned before attempting the safetying operation. Never over torque or loosen a torqued nut to align safety wire holes. Oil Caps, Drain Cocks, & Valves These units are safety wired as shown in Figure 7-73. In the case of the oil cap, the wire is anchored to an adjacent fillister head screw. 7-78 A Clip-locking method B Wire-wrapping method Straight end Hook lip Hook loop Hook end Loop end Hook shoulder Direction of pull for inspection 4 turn (min) This applies to all turnbuckle wrappings Double wrap (spiral) Double wrap Single wrap (spiral) Single wrap 7-79 Cable size (inch) Type of Wrap Diameter of Safety Wire (inch) Material (Annealed Condition) Single Double Single 0.020 0.040 0.057 Stainless steel Copper, brass1 Stainless steel Copper, brass1 Stainless steel 1Galvanized or tinned steel, or soft iron wires are also acceptable.

5⁄32 and greater PreferredOptional This system applies to any other unit that must be safety wired individually. Ordinarily, anchorage lips are conveniently located near these individual parts. When such provision is not made, the safety wire is fastened to some adjacent part of the assembly. Electrical Connectors Under conditions of severe vibration, the coupling nut of a connector may vibrate loose and, with sufficient vibration, the connector may come apart. When this occurs, the circuit carried by the cable opens. The proper protective measure to prevent this occurrence is by safety wiring as shown in and must be installed in such a manner that the pull on the wire is in the direction that tightens the nut on the plug.

Turnbuckles After a turnbuckle has been properly adjusted, it must be safetied. There are several methods of safetying turnbuckles; however, only two methods are discussed in this section. These methods are illustrated in Figure 7-75. The clip locking method is used only on the most modern aircraft. The older type aircraft still use the type turnbuckles that require the wire wrapping method. Double Wrap Method Of the methods using safety wire for safetying turnbuckles, the double wrap method is preferred, although the single wrap methods described are satisfactory. The method of double wrap safetying is shown in Figure 7-75. Use two separate lengths of the proper wire as shown in Figure 7-76.

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. Then 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. Then pass the wires at the end of the turnbuckle in opposite directions through the holes in the turnbuckle eyes or between the jaws of the turnbuckle fork, as applicable. Bend the laid wires in place before cutting off the wrapped wire. 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.

When a swaged terminal is being safetied, pass the ends of both wires, if possible, through the hole provided in the terminal for this purpose and wrap both ends around the shank as described above. 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 described. Single Wrap Method The single wrap safetying methods described in the following paragraphs are acceptable but are not the equal of the double wrap methods. 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 1⁄16 3⁄32 1⁄8 7-80 Shaft Snap ring Single-wire method turnbuckle assembly. Spiral each of the wire ends in opposite directions around the first half of the turnbuckle barrel so that the wires cross each other twice. Thread both wire ends through the hole in the middle of the barrel so that the third crossing of the 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 terminal. In the manner described above, wrap both wire ends around the shank for at least four turns each, cutting off the excess wire.

An alternate to the above method is to 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 end around the shank for at least four turns, cutting off the excess wire. After safetying, no more than three threads of the turnbuckle threaded terminal should be exposed. General Safety Wiring Rules When using the safety wire method of safetying, the following general rules should be followed: 1. Pigtail of 1⁄4 to 1⁄2 inch (three to six twists) should be made at the end of the wiring. This pigtail must be bent back or under to prevent it from becoming a snag.

2. The safety wire must be new upon each application. 3. 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 aligns with the hole. 4. All safety wires must be tight after installation, but not under such tension that normal handling or vibration breaks the wire. 5. The wire must be applied so that all pull exerted by the wire tends to tighten the nut. 6. Twists should be tight and even, and the wire between the nuts as taut as possible without over twisting.

7. The safety wire should always be installed and twisted so that the loop around the head stays down and does not tend to come up over the bolt head, causing a slack loop. Cotter Pin Safetying Cotter pin installation is shown in Figure 7-77. Castellated nuts are used with bolts that have been drilled for cotter pins. The cotter pin should fit neatly into the hole with very little side play. The following general rules apply to cotter pin safetying: 1. The prong bent over the bolt end should not extend beyond the bolt diameter. (Cut it off if necessary.) 2. The prong bent down should not rest against the surface of the washer. (Again, cut it off if necessary.) 3. If the optional wraparound method is used, the prongs should not extend outward from the sides of the nut.

4. All prongs should be bent over a reasonable radius. Sharp angled bends invite breakage. Tapping lightly with a mallet is the best method of bending the prongs. Snap Rings A snap ring is a ring of metal, either round or flat in cross section, which is tempered to have spring like action. This spring like action holds the snap ring firmly seated in a groove. The external types are designed to fit in a groove around the outside of a shaft or cylinder and may be safety wired. Safety wiring of an external type snap ring is shown in Figure 7-78. The internal types fit in a groove inside a cylinder and are never safetied. A special type of pliers is designed to install each type of snap ring. Snap rings can be reused as long as they retain their shape and spring-like action.