Par 11-212 Page 11-95
a. Thermal cure inks must generally be heated in an oven for a length of time after marking to obtain their durability. UV cure inks are cured in line much like dot matrix.
b. Ink jet marks the wire on the fly and makes a reasonably durable and legible mark without damaging the insulation. Ink jets normally mark wire from 0.030- to 0.25-inch outside diameter. Multiconductor cable can also be marked.
11-213. LASER MARKING. Of the variety of laser marking machines, UV lasers are proving to be the best. This method marks into the surface of the wire’s insulation without degradation to its performance. One common type of UV laser is referred to as an excimer laser marker. UV laser produces the most durable marks because it marks into the insulation instead of on the surface. However, excimer laser will only mark insulation that contain appropriate percentages of titanium dioxide (TiO2). The wire can be marked on the fly. UV can mark from 0.030- to
0.25-inch outside diameter. The UV laser makes only gray marks and they appear more legible on white or pastel-colored insulation.
11-214. IDENTIFICATION SLEEVES. Flexible sleeving, either clear or opaque, is satisfactory for general use. When color-coded or striped component wire is used as part of a cable, the identification sleeve should specify which color is associated with each wire identification code. Identification sleeves are normally used for identifying the following types of wire or cable:
a. Unjacketed shielded wire.
b. Thermocouple wire identification is normally accomplished by means of identification sleeves. As the thermocouple wire is usually of the duplex type (two insulated wires within the same casing), each wire at the termination point bears the full name of the conductor.
Thermocouple conductors are alumel, chromel, iron, constantan, and copper constantan.
c. Coaxial cable should not be hot stamped directly. When marking coaxial cable, care should be taken not to deform the cable as this may change the electrical characteristics of the cable. When cables cannot be printed directly, they should be identified by printing the identification code (and individual wire color, where applicable) on a nonmetallic material placed externally to the outer covering at the terminating end and at each junction or pressure bulkhead. Cables not enclosed in conduit or a common jacket should be identified with printed sleeves at each end and at intervals not longer than 3 feet. Individual wires within a cable should be identified within 3 inches from their termination.
d. Multiconductor cable normally use identification sleeves for identifying unshielded, unjacketed cable.
e. High-temperature wire with insulation is difficult to mark (such as Teflon and fiberglass).
11-215. IDENTIFICATION TAPE. Identification tape can be used in place of sleeving, in most cases (i.e., polyvinyl fluoride).
Par 11-216 Page 11-96
11-216. OPERATING CONDITIONS. For sleeving exposed to high temperatures (over 400 °F), materials such as silicone fiberglass should be used.
11-217. INSTALLATION OF PRINTED SLEEVES. Polyolefin sleeving should be used in areas where resistance to solvent and synthetic hydraulic fluids is necessary. Sleeves may be secured in place with cable ties or by heat shrinking. The identification sleeving for various sizes of wire is shown in Table 11-19.
TABLE 11-19. RECOMMENDED SIZE OF IDENTIFICATION SLEEVING Wire Size Sleeving Size AN AL No. Nominal ID (inches) #24 12 .085 #22 11 .095 #20 10 .106 #18 9 .118 #16 8 .113 #14 7 .148 #12 6 .166 #10 4 .208 #8 #8 2 .263 #6 #6 0 .330 #4 #4 3/8 inch .375 #2 #2 1/2 inch .500 #1 #1 1/2 inch .500 #0 #0 5/8 inch .625 #00 #00 5/8 inch .625 #000 #000 3/4 inch .750 #0000 #0000 3/4 inch .750
11-218. IDENTIFICATION OF WIRE BUNDLES AND HARNESSES. The identification of wire bundles and harnesses is becoming a common practice and may be accomplished by the use of a marked sleeve tied in place or by the use of pressure-sensitive tape as indicated in Figure 11-25.
Par 11-218 Page 11-97 FIGURE 11-25. IDENTIFICATION OF WIRE BUNDLES AND HARNESSES
a. Wires for which identifications are reassigned after installation may be remarked on sleeves at the termination of each wire segment. It may be necessary to re-identify such wires throughout their lengths to facilitate ease of maintenance.
b. For high-density harnessed, shielded, and jacketed multiconductor cables and when using nonsignificant wire identification, color coding or its alphanumeric equivalent may be interchanged within the same harnesses. The alphanumeric equivalent of the color code should be as set forth in MIL-STD-681.
11-219. TERMINAL MARKING SLEEVE AND TAGS. Typical cable markers are flat, nonheat-shrinkable tags. Heat shrinkable marking sleeves are available for marking wires and cables, and should be inserted over the proper wire or cable and heat shrunk using the proper manufacturer recommended heating tool. (See Figures 11-26 and 11-27.)
FIGURE 11-26. STANDARD SLEEVES (135 °C)
Par 11-219 Page 11-98 FIGURE 11-27. INSTALLATION OF HEAT-SHRINKABLE INSULATION SLEEVES
11-220. SLEEVES AND CABLE MARKERS SELECTION. Sleeves and cable markers must be selected by cable size and operating conditions. (See Tables 11-20 through 11-23).
a. Markers are printed using a typewriter with a modified roller. Blank markers on a bandolier are fed into the typewriter, where they are marked in any desired combination of characters. The typed markers, still on bandoliers, are heated in an infrared heating tool that processes the markers for permanency. The typed and heat-treated markers remain on the bandolier until ready for installation.
b. Markers are normally installed using the following procedure:
(1) Select the smallest tie-down strap that will accommodate the outside diameter of the cable. (See Table 11-24.)
(2) Cut the marking plate from the bandolier. (See Figure 11-28.)
(3) Thread the tie-down straps through holes in marking plate and around cable. Thread tip of tie-down strap through slot in head. (See Figure 11-29.) Pull tip until strap is snug around cable.
Par 11-220 Page 11-99 FIGURE 11-28. CABLE MARKERS FIGURE 11-29. TIE-DOWN STRAP INSTALLATION
Par 11-220 Page 11-100 TABLE 11-20. SELECTION TABLE FOR STANDARD SLEEVES Wire or Cable Diameter Range (inches) Markable Length * (inches) Installed Sleeve Length (nom) (inches) Installed Wall Thickness (max inches) As-Supplied Inside Diameter (min inches) Min Max
0.050 0.080 18 1.5 0.026 0.093
0.075 0.110 18 1.5 0.026 0.125
0.100 0.150 18 1.5 0.028 0.187
0.135 0.215 18 1.5 0.028 0.250
0.200 0.300 18 1.5 0.028 0.375
0.135 0.300 18 1.5 0.028 0.375
0.260 0.450 18 1.5 0.028 0.475 * Based on 12 characters per inch TABLE 11-21. SELECTION TABLE FOR THIN-WALL SLEEVES Wire or Cable Diameter Range (inches) Markable Length * (inches) Installed Sleeve Length (nom) (inches) Installed Wall Thickness (max inches) As-Supplied Inside Diameter (min inches) Min. Max.
0.035 0.080 22 1.75 0.020 0.093
0.075 0.110 22 1.75 0.020 0.125
0.100 0.150 21 1.75 0.021 0.187
0.135 0.225 21 1.75 0.021 0.250 * Based on 12 characters per inch
Par 11-220 Page 11-101 TABLE 11-22. SELECTION TABLE FOR HIGH-TEMPERATURE SLEEVES Wire or Cable Diameter Range (inches) Markable Length * (inches) Installed Sleeve Length (nom) (inches) Installed Wall Thickness (max inches) As-Supplied Inside Diameter (min inches) Min Max
0.035 0.080 18 1.5 0.019 0.093
0.075 0.110 18 1.5 0.016 0.125
0.100 0.150 18 1.5 0.018 0.187
0.135 0.215 18 1.5 0.018 0.250
0.200 0.300 18 1.5 0.018 0.375
0.260 0.450 18 1.5 0.018 0.475 * Based on 12 characters per inch TABLE 11-23. SELECTION TABLE FOR CABLE MARKERS Cable Diameter Range (inches) Type of Cable Marker Number of Attachment Holes Number of Lines of Type Marker Thickness (nom) (inches)
0.25-0.50 Standard, 135 °C 4 2 0.025
0.25-0.50 High Temperature, 200 °C 4 2 0.020
0.25-0.50 Nuclear, 135 °C 4 2 0.025
0.50-up Standard, 135 °C 4 3 0.025
0.50-up Standard, 135 °C 6 3 0.025
0.50-up High Temperature, 200 °C 4 3 0.020
0.50-up High Temperature, 200 °C 6 3 0.020
0.50-up Nuclear, 135 °C 4 3 0.025
0.50-up Nuclear, 135 °C 6 3 0.025
Par 11-220 Page 11-102 TABLE 11-24. PLASTIC TIE-DOWN STRAPS (MS3367, TYPE I, CLASS 1) Cable Diameter (inches) Tie-Down Strap MS3367- Strap Identification * Installation Tool Tension Setting Min Max 1/16 5/8 4-9 Miniature (MIN) MS90387-1 2 1/16 1¼ 5-9 Intermediate (INT) MS90387-1 4 1/16 4 2-9 Standard (STD) MS90387-1 6 3/16 8 6-9 Heavy (HVY) MS90387-2 6 * The specified tool tension settings are for typical cable application. Settings less than or greater than those specified may be required for special applications.
(4) Select the applicable installation tool and move the tension setting to the correct position. (See Figure 11-30.)
(5) Slide tip of strap into opening in the installation tool nose piece. (See Figure 11-30.)
FIGURE 11-30. TIE-DOWN STRAP INSTALLATION TOOL (
6) Keeping tool against head of tie-down strap, ensure gripper engages tie-down strap, and squeeze trigger of installation tool until strap installation is completed as shown in Figure 11-31.
Par 11-220 Page 11-103 FIGURE 11-31. COMPLETED INSTALLATION 11 -221. TEMPORARY WIRE AND CABLE MARKING PROCEDURE. A temporary wire marking procedure follows but should be used only with caution and with plans for future permanence. (See Figure 11-32.)
FIGURE 11-32. TEMPORARY WIRE IDENTIFICATION MARKER
a.
With a pen or a typewriter, write wire number on good quality white split insulation sleeve.
b. Trim excess white insulation sleeve, leaving just enough for one wrap around wire to be marked, with number fully visible.
c. Position marked white insulation sleeve on wire so that shielding, ties, clamps, or supporting devices need not be removed to read the number.
d. Obtain clear plastic sleeve that is long enough to extend 1/4 inch past white insulation sleeve marker edges and wide enough to overlap itself when wrapped around white insulation and wire.
e. Slit clear sleeve lengthwise and place around marker and wire.
f. Secure each end of clear sleeve with lacing tape spot tie to prevent loosening of sleeve.
11-222. MARKER SLEEVE INSTALLATION AFTER PRINTING. The following general procedures apply:
Par 11-222 Page 11-104
a. Hold marker, printed side up, and press end of wire on lip of sleeve to open sleeve.
(See Figure 11-33.)
FIGURE 11-33. INSERTING WIRE INTO MARKER
b. If wire has been stripped, use a scrap piece of unstripped wire to open the end of the marker.
c. Push sleeve onto wire with a gentle twisting motion.
d. Shrink marker sleeve, using heat gun with shrink tubing attachment. (See Figure 11-34.)
FIGURE 11-34. SHRINKING MARKER ON WIRE 11 -223.–11-229. [RESERVED.]
Par 11-230 Page 11-105 SECTION 17. CONNECTORS
11-230. GENERAL. There is a multitude of types of connectors. Crimped contacts are generally used. Some of the more common are the round cannon type, the rectangular, and the module blocks. Environmental resistant connectors should be used in applications subject to fluids, vibration, thermal, mechanical shock, and/or corrosive elements. When High Intensity Radiated Fields (HIRF)/Lightning protection is required, special attention should be given to the terminations of individual or overall shields. The number and complexity of wiring systems have resulted in an increased use of electrical connectors. The proper choice and application of connectors is a significant part of the aircraft wiring system. Connectors must be kept to a minimum, selected, and installed to provide the maximum degree of safety and reliability to the aircraft. For the installation of any particular connector assembly, the specification of the manufacturer or the appropriate governing agency must be followed.
11-231. SELECTION. Connectors should be selected to provide the maximum degree of safety and reliability considering electrical and environmental requirements. Consider the size, weight, tooling, logistic, maintenance support, and compatibility with standardization programs. For ease of assembly and maintenance, connectors using crimped contacts are generally chosen for all applications except those requiring a hermetic seal. (Refer to SAE ARP1308, Preferred Electrical Connectors for Aerospace, Shipboard, Ground Vehicles and Associated Equipment.) A replacement connector of the same basic type and design as the connector it replaces should be used. With a crimp-type connector for any electrical connection, the proper insertion or extraction tool must be used to install or remove wires from such a connector. Refer to manufacturer or aircraft instruction manual. After the connector is disconnected, inspect it for loose soldered connections to prevent unintentional grounding. Connectors that are susceptible to corrosion difficulties may be treated with a chemically inert waterproof jelly.
11-232. TYPES OF CONNECTORS. Connectors must be identified by an original identification number derived from MIL Specification (MS) or OAM specification. Figure 11-35 provides some examples of MS connector types. Several different types are shown in Figures 11-36 and 11-37.
a. Environmental Classes. Environment-resistant connectors are used in applications where they will probably be subjected to fluids, vibration, thermal, mechanical shock, corrosive elements, etc. Firewall class connectors incorporating these same features should, in addition, be able to prevent the penetration of the fire through the aircraft firewall connector opening and continue to function without failure for a specified period of time when exposed to fire. Hermetic connectors provide a pressure seal for maintaining pressurized areas. When EMI/RFI protection is required, special attention should be given to the termination of individual and overall shields.
Back shell adapters designed for shield termination, connectors with conductive finishes, and EMI grounding fingers are available for this purpose.
b. Rectangular Connectors. The rectangular connectors are typically used in applications where a very large number of circuits are accommodated in a single mated pair. They are available with a great variety of contacts, which can include a mix of standard, coaxial, and large power types. Coupling is accomplished by various means. Smaller types are secured with screws which hold their flanges together. Larger ones have integral guide pins that ensure correct
Par 11-232 Page 11-106 alignment, or jackscrews that both align and lock the connectors. Rack and panel connectors use integral or rack-mounted pins for alignment and box mounting hardware for couplings.
c. Module Blocks. These junctions accept crimped contacts similar to those on connectors. Some use internal busing to provide a variety of circuit arrangements. They are useful where a number of wires are connected for power or signal distribution. When used as grounding modules, they save and reduce hardware installation on the aircraft. Standardized modules are available with wire end grommet seals for environmental applications and are track-mounted. Function module blocks are used to provide an easily wired package for environment-resistant mounting of small resistors, diodes, filters, and suppression networks.
In-line terminal junctions are sometimes used in lieu of a connector when only a few wires are terminated and when the ability to disconnect the wires is desired. The in-line terminal junction is environment-resistant. The terminal junction splice is small and may be tied to the surface of a wire bundle when approved by the OAM.