9/8/98 AC 43.13-1B CHAPTER 11. AIRCRAFT ELECTRICAL SYSTEMS SECTION 1. INSPECTION AND CARE OF ELECTRICAL SYSTEMS 11-1. GENERAL. The term “electrical system” as used in this AC means those parts of the aircraft that generate, distribute, and use electrical energy, including their support and attachments. The satisfactory performance of an aircraft is dependent upon the continued reliability of the electrical system.
AC 43.13-1B 9/8/98 m. Voltage check of electrical system with portable precision voltmeter. n. Condition of electric lamps. o. Missing safety shields on exposed high-voltage terminals (i.e., 115/200V ac). 11-3. FUNCTIONAL CHECK OF STAND-BY OR EMERGENCY EQUIPMENT. An aircraft should have functional tests performed at regular intervals as prescribed by the manufacturer.
9/8/98 AC 43.13-1B 11-8. BUS BARS. Annually check bus bars for general condition, cleanliness, and security of all attachments and terminals. Grease, corrosion, or dirt on any electrical junction may cause the connections to overheat and eventually fail. Bus bars that exhibit corrosion, even in limited amounts, should be disassembled, cleaned and brightened, and reinstalled. 11-9. 11-14. [RESERVED.
9/8/98 AC 43.13-1B SECTION 2. STORAGE BATTERIES 11-15. GENERAL. Aircraft batteries may be used for many functions, e.g., ground power, emergency power, improving DC bus stability, and fault-clearing. Most small private aircraft use lead-acid batteries. Most commercial and military aircraft use NiCad batteries. However, other types are becoming available such as gel cell and sealed lead-acid batteries.
AC 43.13-1B 9/8/98 hydrometer indication. As an example, a hydrometer reading of 1.260 and the temperature of the electrolyte at 40 °F, the corrected specific gravity reading of the electrolyte is 1.244. TABLE 11-2. Sulfuric acid temperature correction.
9/8/98 e. Battery and Charger Characteristics. The following information is provided to acquaint the user with characteristics of the more common aircraft battery and battery charger types. Products may vary from these descriptions due to different applications of available technology. Consult the manufacturer for specific performance data. NOTE: Under no circumstances connect a lead-acid battery to a charger, unless properly serviced. (1) Lead-acid vented batteries have a two volt nominal cell voltage.
AC 43.13-1B having a shorted cell might overheat due to excessive overcharge and undergo a thermal runaway, destroying the battery and creating a possible safety hazard to the aircraft. DEFINITION: Thermal runaway can result in a chemical fire and/or explosion of the NiCad battery under recharge by a constant-voltage source, and is due to cyclical, ever-increasing temperature and charging current.
/8/98 AC 43.13-1B neutralize with a solution of baking soda and water, and shower or flush the affected area with water. For the eyes, use an eye fountain and flush with an abundance of water. If potassium hydroxide contacts the skin, neutralize with 9 percent acetic acid, vinegar, or lemon juice and wash with water. For the eyes, wash with a weak solution of boric acid or a weak solution of vinegar and flush with water. 11-21. NOXIOUS FUMES.
AC 43.13-1B may normally be avoided by insulating the terminal posts during the installation process. Remove the grounding lead first for battery removal, then the positive lead. Connect the grounding lead of the battery last to minimize the risk of shorting the “hot terminal” of the battery during installation. f. Battery Hold Down Devices.
9/27/01 AC 43.13-1B CHG 1 SECTION 3. INSPECTION OF EQUIPMENT INSTALLATION 11-30. GENERAL. When installing equipment which consumes electrical power in an aircraft, it should be determined that the total electrical load can be safely controlled or managed within the rated limits of the affected components of the aircraft’s electrical power supply system. Addition of most electrical utilization equipment is a major alteration and requires appropriate FAA approval.
AC 43.13-1B CHG 1 11-35. ACCEPTABLE MEANS OF CONTROLLING OR MONITORING THE ELECTRICAL LOAD. a. Output Rating. The generator or alternator output ratings and limits prescribed by the manufacturer must be checked against the electrical loads that can be imposed on the affected generator or alternator by installed equipment.
9/27/01 data should provide a true picture of the status of the electrical system. New or additional electrical devices should not be installed in an aircraft, nor the capacity changed of any power source, until the status of the electrical system in the aircraft has been determined accurately and found not to adversely affect the integrity of the electrical system. 11-37. JUNCTION BOX CONSTRUCTION.
9/8/98 AC 43.13-1B SECTION 4. INSPECTION OF CIRCUIT-PROTECTION DEVICES 11-47. GENERAL. All electrical wires must be provided with some means of circuit protection. Electrical wire should be protected with circuit breakers or fuses located as close as possible to the electrical power source bus. Normally, the manufacturer of electrical equipment will specify the fuse or breaker to be used when installing the respective equipment, or SAE publication, ARP 1199, may be referred to for recommended practices.
AC 43.13-1B CHG 1 9/27/01 or components. Use of a circuit breaker as a switch is not recommended. Use of a circuit breaker as a switch will decrease the life of the circuit breaker. b. Electromechanical Switches. Switches have electrical contacts and various types of switch actuators (i.e., toggle, plunger, push-button, knob, rocker). 11-52. CIRCUIT BREAKER MAINTENANCE.
9/8/98 AC 43.13-1B armature and field coils is released when the control switch is opened. e. Switch Selection. Switches for aircraft use should be selected with extreme caution. The contact ratings should be adequate for all load conditions and applicable voltages, at both sea level and the operational altitude. Consideration should be given to the variation in the electrical power characteristics, using MIL-STD-704 as a guide. f. Derating Factors.
AC 43.13-1B CHG 1 (2) Typical low-level load devices have a voltage of less than 0.5 volts and a continuous current of less than 0.5 amps. A suitable method of rating switches for use on logic load devices is specified in ANSI/EIA 5200000. h. Shock and Vibration. (1) Electromechanical switches (toggle switches) are most susceptible to shock and vibration in the plane that is parallel to contact motion. Under these conditions the switch contacts may momentarily separate.
9/8/98 (1) Electromechanical switches range in sealing from partially sealed to hermetically sealed. Use a sealed switch when the switch will be exposed to a dirty environment during storage, assembly, or operation. Use a higher level of sealing when the switch will not have an arcing load to self-clean the contacts. Lowenergy loads tend to be more susceptible to contamination.
AC 43.13-1B CHG 1 insulation of the electrically “live” components) is especially vulnerable to catastrophic failure as a result of overtorquing. (1) When replacing relays in alternating current (ac) applications, it is essential to maintain proper phase sequencing. For any application involving plug-in relays, proper engagement of their retaining mechanism is vital. (2) The proximity of certain magnetically permanent, magnet assisted, coil operated relays may cause them to have an impact on each other.
9/27/01 AC 43.13-1B CHG 1 SECTION 5. ELECTRICAL WIRE RATING 11-66. GENERAL. Wires must be sized so that they: have sufficient mechanical strength to allow for service conditions; do not exceed allowable voltage drop levels; are protected by system circuit protection devices; and meet circuit current carrying requirements. a. Mechanical Strength of Wires.
AC 43.13-1B CHG 1 9/27/01 TABLE 11-7. Examples of determining required tinplated copper wire size and checking voltage drop using figure 11-2 Wire Size From Chart Voltage drop Run Lengths (Feet) Circuit Current (Amps) 1 107 20 No. 6 0.5 90 20 No. 4 4 88 20 No. 12 7 100 20 No. 14 Checkcalculated voltage drop (VD)= (Resistance/Ft) (Length) (Current) VD= (.00044 ohms/ft) (107)(20)= 0.942 VD= (.00028 ohms/ft) (90)(20)= 0.504 VD= (.00202 ohms/ft) (88)(20)= 3.60 VD= (.
9/27/01 Where: T1 = T2 = TR = I2 = Imax = AC 43.13-1B CHG 1 Ambient Temperature Estimated Conductor Temperature Conductor Temperature Rating Circuit Current (A=Amps) Maximum Allowable Current (A=Amps) at TR This formula is quite conservative and will typically yield somewhat higher estimated temperatures than are likely to be encountered under actual operating conditions.
AC 43.13-1B CHG 1 9/27/01 TABLE 11-10. Current carrying capacity and resistance of aluminum wire. Continuous duty current (amps) Wires in bundles, groups or harnesses Max. resistance or conduits (See table 11-9 Note #1) ohms/1000ft Wire conductor temperature rating @ 20 °C 105 °C 150 °C 8 30 45 1.093 6 40 61 0.641 4 54 82 0.427 2 76 113 0.268 1 90 133 0.214 0 102 153 0.169 00 117 178 0.133 000 138 209 0.109 0000 163 248 0.
9/27/01 AC 43.13-1B CHG 1 11-67. c. Single Wire in Free Air. Determining a wiring system’s current carrying capacity begins with determining the maximum current that a given-sized wire can carry without exceeding the allowable temperature difference (wire rating minus ambient °C). The curves are based upon a single copper wire in free air. (See figures 11-4a and 11-4b.) METHODS FOR DETERMINING CURRENT CARRYING CAPACITY OF WIRES.
AC 43.13-1B CHG 1 9/27/01 (1) The wire size should be sufficient to prevent an excessive voltage drop while carrying the required current over the required distance. (See table 11-6, Tabulation Chart, for allowable voltage drops.) (2) The size should be sufficient to prevent overheating of the wire carrying the required current. (See paragraph 11-69 for allowable current carrying calculation methods.) b. Two Requirements.
9/27/01 AC 43.13-1B CHG 1 current at an elevated conductor temperature using the following information: (1) The wire run is 15.5 feet long, including the ground wire. (2) Circuit current (I2) is 20 amps, continuous. (3) The voltage source is 28 volts. (4) The wire type used has a 200 °C conductor rating and it is intended to use this thermal rating to minimize the wire gauge. Assume that the method described in paragraph 11-66d(6) was used and the minimum wire size to carry the required current is #14.
AC 43.13-1B CHG 1 The size #14 wire selected using the methods outlined in paragraph 11-66d is too small to meet the voltage drop limits from figure 11-2 for a 15.5 feet long wire run. STEP 3: Select the next larger wire (size #12) and repeat the calculations as follows: L1=24 feet maximum run length for 12 gauge wire carrying 20 amps from figure 11-2. Imax = 37 amps (this is the maximum current the size #12 wire can carry at 50 °C ambient.
9/27/01 multiplied by the derated capacity (10 x 8.8 = 88 amps) and multiply the sum by the 20 percent harness capacity factor. Thus, the total harness capacity is (165.0 + 88.0) x 0.20 = 50.6 amps. It has been determined that the total harness current should not exceed 50.6 A, size #22 wire should not carry more than 6.6 amps and size #20 wire should not carry more than 8.8 amps. STEP 6: Determine the actual circuit current for each wire in the bundle and for the whole bundle.
AC 43.13-1B CHG 1 9/27/01 FIGURE 11-2. Conductor chart, continuous flow.
9/27/01 AC 43.13-1B CHG 1 FIGURE 11-3. Conductor chart, intermittent flow.
AC 43.13-1B CHG 1 9/27/01 FIGURE 11-4a. Single copper wire in free air.
9/27/01 AC 43.13-1B CHG 1 FIGURE 11-4b. Single copper wire in free air.
AC 43.13-1B CHG 1 9/27/01 FIGURE 11-5. Bundle derating curves.
9/27/01 AC 43.13-1B CHG 1 FIGURE 11-6. Altitude derating curve. 11-70. – 11-75. [RESERVED.
9/8/98 AC 43.13-1B SECTION 6. AIRCRAFT ELECTRICAL WIRE SELECTION 11-76. GENERAL. Aircraft service imposes severe environmental condition on electrical wire. To ensure satisfactory service, inspect wire annually for abrasions, defective insulation, condition of terminations, and potential corrosion.
AC 43.13-1B CHG 1 sources. Such military or original equipment manufacturer (OEM) wire used on aircraft should only have originated from these defined wire mills. Aircraft wire from other unauthorized firms, and fraudulently marked with the specified identification, must be regarded as “unapproved wire,” and usually will be of inferior quality with little or no process control testing. Efforts must be taken to ensure obtaining authentic, fully tested aircraft wire. b. Plating.
9/27/01 AC 43.13-1B CHG 1 aerospace applications in open and protected wiring applications. These wires could potentially be used for substitution when approved by the OAM. b. Areas designated as severe wind and moisture problem (SWAMP) areas differ from aircraft to aircraft but generally are considered to be areas such as wheel wells, near wing flaps, wing folds, pylons, and other exterior areas that may have a harsh environment.
9/27/01 AC 43.13-1B CHG 1 SECTION 7. TABLE OF ACCEPTABLE WIRES 11-85. AIRCRAFT WIRE TABLE. Tables 11-11 and 11-12 list wires used for the transmission of signal and power currents in aircraft. It does not include special purpose wires such as thermocouple, engine vibration monitor wire, fiber optics, data bus, and other such wire designs. Fire resistant wire is included because it is experiencing a wider application in aircraft circuits beyond that of the fire detection systems. a.
AC 43.13-1B CHG 1 9/27/01 TABLE 11-11. Open Wiring.
9/27/01 AC 43.13-1B CHG 1 TABLE 11-12. Protected wiring.
9/8/98 AC 43.13-1B SECTION 8. WIRING INSTALLATION INSPECTION REQUIREMENTS 11-96. GENERAL. Wires and cables should be inspected for adequacy of support, protection, and general condition throughout. The desirable and undesirable features in aircraft wiring installations are listed below and indicate conditions that may or may not exist.
AC 43.13-1B CHG 1 n. Ensure cable supports do not restrict the wires or cables in such a manner as to interfere with operation of equipment shock mounts. o. Do not use tape, tie straps, or cord for primary support. p. Make sure that drain holes are present in drip loops or in the lowest portion of tubing placed over the wiring. q. Ensure that wires and cables are routed in such a manner that chafing will not occur against the airframe or other components. r.
9/27/01 AC 43.13-1B CHG 1 verse direction in a bundle. Where the wire is suitably supported, the radius may be 3 times the diameter of the wire or cable. Where it is not practical to install wiring or cables within the radius requirements, the bend should be enclosed in insulating tubing. The radius for thermocouple wire should be done in accordance with the manufacturer’s recommendation and shall be sufficient to avoid excess losses or damage to the cable. bb. Ensure that RF cables, e.g.
AC 43.13-1B CHG 1 e. Check wiring that shows evidence of overheating (even if only to a minor degree) for the cause of the overheating. f. Wiring on which the insulation has become saturated with engine oil, hydraulic fluid, or another lubricant. g. Wiring that bears evidence of having been crushed or severely kinked. h. Shielded wiring on which the metallic shield is frayed and/or corroded.
9/27/01 i. Terminations should be made using terminals of the proper size and the appropriate terminal crimping tools. 11-99. FUSES AND FUSE HOLDERS. Inspect as follows: a. Check security of connections to fuse holders. b. Inspect for the presence of corrosion and evidence of overheating on fuses and fuse holders. Replace corroded fuses and clean fuse holders. If evidence of overheating is found, check for correct rating of fuse. c. Check mounting security of fuse holder. d.
AC 43.13-1B CHG 1 9/27/01 wiring must be clearly identified and must be routed and clamped so that it cannot be mismatched. FLEXIBLE METALLIC AND RIGID NONMETALLIC. Inspection of conduit assemblies should ascertain that: j. Connectors in unpressurized areas should be positioned so that moisture will drain out of them when unmated. Wires exiting connectors must be routed so that moisture drains away from them. a. Conduit is relieved of strain and flexing of ferrules. 11-101.
9/27/01 b. Exposed junctions and buses should be protected with insulating materials. Junctions and buses located within enclosed areas containing only electrical and electronic equipment are not considered as exposed. c. Electrical junctions should be mechanically and electrically secure. They should not be subject to mechanical strain or used as a support for insulating materials, except for insulation on terminals. 11-104. CIRCUIT BREAKERS.
AC 43.13-1B CHG 1 c. All associated electrically operated equipment and systems on the airplane must be on and operating before conducting interference tests, unless otherwise specified. d. The effects on interference must be evaluated as follows: (1) The equipment shall not be the source of harmful conducted or radiated interference or adversely affect other equipment or systems installed in the airplane.
9/27/01 AC 43.13-1B CHG 1 SECTION 9. ENVIRONMENTAL PROTECTION AND INSPECTION 11-115. MAINTENANCE AND OPERATIONS. Wire bundles must be routed in accessible areas that are protected from damage from personnel, cargo, and maintenance activity. They should not be routed in areas in where they are likely to be used as handholds or as support for personal equipment or where they could become damaged during removal of aircraft equipment.
AC 43.13-1B CHG 1 b. Care should be taken to avoid sharp bends in wires that have been marked with the hot stamping process. 11-118. SLACK. Wiring should be installed with sufficient slack so that bundles and individual wires are not under tension. Wires connected to movable or shock-mounted equipment should have sufficient length to allow full travel without tension on the bundle. Wiring at terminal lugs or connectors should have sufficient slack to allow two reterminations without replacement of wires.
9/27/01 AC 43.13-1B CHG 1 FIGURE 11-9a. Slack between supports FIGURE 11-9b. Drainage hole in low point of tubing.
9/8/98 AC 43.13-1B a. Wires located on landing gear and in the wheel well area can be exposed to many hazardous conditions if not suitably protected. Where wire bundles pass flex points, there must not be any strain on attachments or excessive slack when parts are fully extended or retracted. The wiring and protective tubing must be inspected frequently and replaced at the first sign of wear. sunlight when aircraft are parked for extended periods should also be taken into account.
AC 43.13-1B 9/8/98 directly to the fluid-carrying equipment. Install clamps as shown in figure 11-10. These clamps should not be used as a means of supporting the wire bundle. Additional clamps should be installed to support the wire bundle and the clamps fastened to the same structure used to support the fluid line(s) to prevent relative motion. FIGURE 11-10. Separation of wires from plumbing lines. 11-127. 11-134. [RESERVED.
9/8/98 AC 43.13-1B SECTION 10. SERVICE LOOP HARNESSES (Plastic Tie Strips) 11-135. GENERAL. The primary function of a service loop harness is to provide ease of maintenance. The components, mounted in the instrument panel and on the lower console and other equipment that must be moved to access electrical connectors, are connected to aircraft wiring through service loops. Chafing in service loop harnesses is controlled using the following techniques. 11-136. SUPPORT.
AC 43.13-1B 9/8/98 c. Service Loop Routing. The service loop harness should be routed directly from the breakout point to the component. The harness should not contact moving mechanical components or linkage, and should not be wrapped or tangled with other service loop harnesses. d. Service Loop Harness Termination. Strain relief should be provided at the service loop harness termination, and is normally provided by the connector manufacturer’s backshell, heat-shrinkable boot, or tubing. 11-140. 11-145.
9/27/01 AC 43.13-1B CHG 1 SECTION 11. CLAMPING 11-146. GENERAL. Wires and wire bundles must be supported by using clamps meeting Specification MS-21919, or plastic cable straps in accessible areas if correctly applied within the restrictions of paragraph 11-158. Clamps and other primary support devices must be constructed of materials that are compatible with their installation and environment, in terms of temperature, fluid resistance, exposure to ultraviolet (UV) light, and wire bundle mechanical loads.
AC 43.13-1B CHG 1 9/27/01 FIGURE 11-11. Safe angle for cable clamps. FIGURE 11-12. Typical mounting hardware for MS-21919 cable clamps.
9/8/98 AC 43.13-1B FIGURE 11-13. Installing cable clamp to structure.
AC 43.13-1B 9/8/98 FIGURE 11-14. Clamping at a bulkhead hole. 11-148. 11-154. [RESERVED.
9/8/98 AC 43.13-1B SECTION 12. WIRE INSULATION AND LACING STRING TIE 11-155. GENERAL. Insulation of wires should be appropriately chosen in accordance with the environmental characteristics of wire routing areas. Routing of wires with dissimilar insulation, within the same bundle, is not recommended, particularly when relative motion and abrasion between wires having dissimilar insulation can occur.
AC 43.13-1B 9/8/98 TABLE 11-13. Allowable nicked or broken strands.
9/8/98 AC 43.13-1B FIGURE 11-15. Single cord lacing. FIGURE 11-16. Double cord lacing.
AC 43.13-1B 9/8/98 FIGURE 11-17. Making ties. 11-160. 11-166. [RESERVED.
9/8/98 AC 43.13-1B SECTION 13. SPLICING. 11-167. GENERAL. Splicing is permitted on wiring as long as it does not affect the reliability and the electromechanical characteristics of the wiring. Splicing of power wires, coaxial cables, multiplex bus, and large gauge wire must have approved data. a. Splicing of electrical wire should be kept to a minimum and avoided entirely in locations subject to extreme vibrations.
9/27/01 AC 43.13-1B CHG 1 SECTION 14. TERMINAL REPAIRS 11-174. GENERAL. Terminals are attached to the ends of electrical wires to facilitate connection of the wires to terminal strips or items of equipment. The tensile strength of the wireto-terminal joint should be at least equivalent to the tensile strength of the wire itself, and its resistance negligible relative to the normal resistance of the wire. a. Selection of Wire Terminals. The following should be considered in the selection of wire terminals.
AC 43.13-1B CHG 1 diameter should be placed on the bottom and the smallest diameter on top. Tightening terminal connections should not deform the terminal lugs or the studs. Terminal lugs should be so positioned that bending of the terminal lug is not required to remove the fastening screw or nut, and movement of the terminal lugs will tend to tighten the connection. d. Copper Terminal Lugs. Solderless crimp style, copper wire, terminal lugs should be used and conform to MIL-T-7928.
9/27/01 electric contact efficiency. In other words, the contact pressure on the wire lugs should not in any way be affected by the loosening of the stud in the insulator. d. Support of Wire at Studs. Unless some other positive locking action is provided, the lug or wire should be supported next to the stud to prevent loosening the connection with a side pull on the wire. Torque recommendations for attaching electrical wiring devices to terminal boards or blocks, studs, posts, etc.
AC 43.13-1B CHG 1 9/27/01 any crimping operation and whenever possible during operation to ensure crimp dimensions. 11-179. LOCK WASHERS FOR TERMINALS ON EQUIPMENT. Where locknuts are used to ensure binding and locking of electrical terminals, they should be of the all metal type. In addition, a spring lock washer of suitable thickness may be installed under the nut to ensure good contact pressure. A plain washer should be used between the spring washer and the terminal to prevent galling.
9/27/01 AC 43.13-1B CHG 1 SECTION 15. GROUNDING AND BONDING 11-185. GENERAL. One of the more important factors in the design and maintenance of aircraft electrical systems is proper bonding and grounding. Inadequate bonding or grounding can lead to unreliable operation of systems, e.g., EMI, electrostatic discharge damage to sensitive electronics, personnel shock hazard, or damage from lightning strike.
AC 43.13-1B CHG 1 in order to minimize susceptibility to loosening under vibration. If the structure is fabricated of a material such as carbon fiber composite (CFC), which has a higher resistivity than aluminum or copper, it will be necessary to provide an alternative ground path(s) for power return current. Special attention should be considered for composite aircraft. d. Current Return Paths for Internally Grounded Equipment.
9/8/98 f. Grounds for Sensitive Circuits. Special consideration should be given to grounds for sensitive circuits. For example: (1) Grounding of a signal circuit through a power current lead introduces power current return voltage drop into the signal circuit. (2) Running power wires too close will cause signal interference. (3) Separately grounding two components of a transducer system may introduce ground plane voltage variations into the system.
AC 43.13-1B 9/8/98 e. Self-tapping screws should not be used for bonding purposes. Only standard threaded screws or bolts of appropriate size should be used. ensure proper operation and suppression of radio interference from hazards, electrical bonding of equipment must conform to the manufacturer’s specifications. f. Exposed conducting frames or parts of electrical or electronic equipment should have a low resistance bond of less than 2.5 millohms to structure.
9/8/98 11-189. BONDING JUMPER INSTALLATIONS. Bonding jumpers should be made as short as practicable, and installed in such a manner that the resistance of each connection does not exceed .003 ohm. The jumper should not interfere with the operation of movable aircraft elements, such as surface controls, nor should normal movement of these elements result in damage to the bonding jumper. a. Bonding Connections.
AC 43.13-1B 9/8/98 TABLE 11-14. Stud bonding or grounding to flat surface.
9/8/98 AC 43.13-1B TABLE 11-15. Plate nut bonding or grounding to flat surface.
AC 43.13-1B 9/8/98 TABLE 11-16. Bolt and nut bonding or grounding to flat surface.
9/8/98 AC 43.13-1B FIGURE 11-20. Copper jumper connector to tubular structure. FIGURE 11-21. Bonding conduit to structure. FIGURE 11-22. Aluminum jumper connection to tubular structure.
AC 43.13-1B 11-191. FUEL SYSTEMS. Small metallic objects within an aircraft fuel tank, that are not part of the tank structure, should be electrically bonded to the structure so as to dissipate static charges that may otherwise accumulate on these objects. A practical bonding design would use a flexible braided jumper wire or riveted bracket. In such situations, a DC resistance of 1 ohm or less should indicate an adequate connection.
9/8/98 across each hinge. In any case, not less than two 6500 circular mil jumpers should be used on each control surface. The installation location of these jumpers should be carefully chosen to provide a low-impedance shunt for lightning current across the hinge to the structure. When jumpers may be subjected to arcing, substantially larger wire sizes of 40,000 circular mils or a larger cross section are required to provide protection against multiple strikes.
9/27/01 AC 43.13-1B CHG 1 SECTION 16. WIRE MARKING 11-205. GENERAL. The proper identification of electrical wires and cables with their circuits and voltages is necessary to provide safety of operation, safety to maintenance personnel, and ease of maintenance. a. Each wire and cable should be marked with a part number. It is common practice for wire manufacturers to follow the wire material part number with the five digit/letter C.A.G.E. code identifying the wire manufacturer.
AC 43.13-1B CHG 1 9/27/01 the color should contrast with the wire insula- 3” H215A20 tion or sleeve. 15” 15” H215A20 3” H215A20 (b) Single wire without sleeve FIGURE 11-23. Spacing of printed identification marks (direct marking). a. Extreme care must, therefore, be taken during circuit identification by a hot stamp machine on insulation wall 10 mils or thinner. b. Alternative identification methods such as “Laser Printing”, “Ink Jet”, and “Dot Matrix” are preferred.
9/27/01 contour of the wire, are heated to the desired temperature. Wire is pulled through a channel directly underneath the characters. The heat of the type set characters transfers the ink from the marking foil onto the wire. a. Good marking is obtained only by the proper combination of temperature, pressure, and dwelling. Hot stamp will mark wire with an outside diameter of 0.038 to 0.25-inch. b.
AC 43.13-1B CHG 1 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.
9/27/01 AC 43.13-1B CHG 1 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 reidentify such wires throughout their lengths to facilitate ease of maintenance. FIGURE 11-26. Standard sleeves (135 ºC). b.
AC 43.13-1B CHG 1 9/27/01 doliers, 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: (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.
9/27/01 AC 43.13-1B CHG 1 TABLE 11-19. Selection table for thin-wall sleeves. Wire or Cable Markable Diameter Range Length * (inches) (inches) Min. Max. 0.035 0.080 22 0.075 0.110 22 0.100 0.150 21 0.135 0.225 21 * Based on 12 characters per inch Installed Sleeve Length (nom) (inches) 1.75 1.75 1.75 1.75 Installed Wall Thickness (max inches) As-supplied Inside Diameter (min inches) 0.093 0.125 0.187 0.250 0.020 0.020 0.021 0.021 TABLE 11-20. Selection table for high-temperature sleeves.
AC 43.13-1B CHG 1 9/27/01 (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.) (6) Keeping tool against head of tiedown strap, ensure gripper engages tie-down strap, and squeeze trigger of installation tool until strap installation is completed as shown in figure 11-31. FIGURE 11-32. Temporary wire identification marker. a.
9/27/01 AC 43.13-1B CHG 1 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.
9/27/01 AC 43.13-1B CHG 1 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. Environmentalresistant connectors should be used in applications subject to fluids, vibration, thermal, mechanical shock, and/or corrosive elements.
AC 43.13-1B CHG 1 9/27/01 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.
9/27/01 AC 43.13-1B CHG 1 MS27472 WALL MOUNT RECEPTACLE MS27473 STRAIGHT PLUG MS27474 JAM NUT RECEPTACLE MS27475 HERMITIC WALL MOUNT RECEPTACLE MS27476 HERMETIC BOX MOUNT RECEPTACLE MS27477 HERMETIC JAM NUT RECEPTACLE MS27478 HERMETIC SOLDER MOUNT RECEPTACLE MS27479 WALL MOUNT RECEPTACLE (NOTE 1) MS27480 STRAIGHT PLUG (NOTE 1) MS27481 JAM NUT RECEPTACLE (NOTE 1) MS27482 HERMETIC WALL MOUNT RECEPTACLE (NOTE 1) MS27483 HERMETIC JAM NUT RECEPTACLE (NOTE 1) NOTE 1.
WALL RECEPTACLE CABLE RECEPTACLE QUICK DISCONNECT STRAIGHT PLUG ANGLE PLUG BOX RECEPTACLE STRAIGHT PLUG PLUG ANGLE PLUG MS CONNECTOR TYPICAL RACK AND PANEL CONNECTORS FIGURE 11-36. Different types of connectors.
9/8/98 AC 43.13-1B BNC Series Connectors TNC Series Connectors N Series Connectors C Series Connectors FIGURE 11-37. Coax cable connectors.
AC 43.13-1B 9/8/98 SC Series Connectors SMA Series Connectors SMB Series Connectors SMC Series Connectors FIGURE 11-37. Coax cable connectors (continued).
9/8/98 AC 43.13-1B FIGURE 11-37. Coax cable connectors (continued). 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.
AC 43.13-1B CHG 1 nonpressurized areas. Derating of the connectors should be covered in the specifications. 11-234. SPARE CONTACTS (Future Wiring). To accommodate future wiring additions, spare contacts are normally provided. Locating the unwired contacts along the outer part of the connector facilitates future access. A good practice is to provide: Two spares on connectors with 25 or less contacts; 4 spares on connectors with 26 to 100 contacts; and 6 spares on connectors with more than 100 contacts.
9/8/98 separate strain relief accessory. Strain relief clamps should not impart tension on wires between the clamp and contact. f. Slack. Sufficient wire length must be provided at connectors to ensure a proper drip loop and that there is no strain on termination after a complete replacement of the connector and its contacts. g. Identification. Each connector should have a reference identification that is legible throughout the expected life of the aircraft. 11-236. FEED-THROUGH BULKHEAD WIRE PROTECTION.
AC 43.13-1B moisture in the connectors. A secondary benefit of potting is the reduced possibility of breakage between the contact and wire due to vibration. a. Connectors specifically designed for potting compounds should be potted to provide environment resistance. An o-ring or sealed gasket should be included to seal the interface area of the mated connector. A plastic potting mold, that remains on the connector after the potting compounds have cured, should also be considered.
9/8/98 AC 43.
9/8/98 AC 43.13-1B SECTION 18. CONDUITS 11-248. GENERAL. Conduit is manufactured in metallic and nonmetallic materials and in both rigid and flexible forms. Primarily, its purpose is for mechanical protection of cables or wires.
AC 43.13-1B 11-253. FLEXIBLE CONDUIT. Flexible aluminum conduit conforming to Specification MIL-C-6136 is available in two types: Type I, Bare Flexible Conduit, and Type II, Rubber Covered Flexible Conduit. Flexible brass conduit conforming to Specification MIL-C-7931 is available and normally used instead of flexible aluminum where necessary to minimize radio interference. Also available is a plastic flexible tubing. (Reference MIL-T-8191A.
9/27/01 AC 43.13-1B CHG 1 SECTION 19. UNUSED CONNECTORS AND UNUSED WIRES 11-260. GENERAL. Connectors may have one or more contact cavities that are not used. Depending on the connector installation, unused connector contact cavities may need to be properly sealed to avoid damage to the connector, or have string wire installed.
AC 43.13-1B 9/8/98 TABLE 11-25. Contact cavity sealing-quick reference. Connector Installation Types Unpressurized Area Sealing Means Firewall Non-Firewall Sealing Plugs or Teflon Sealing Rods No Yes Stub Wires (Note 2) Yes No Spare Contacts Yes Yes NOTE 1: Sealing plugs may be included with the spare connector and may be used for sealing unused contacts. Sealing rods are procured from stock by the foot. (See table 11-26 for sealing rod dimensions.
9/8/98 AC 43.13-1B SECTION 20. ELECTRICAL AND ELECTRONIC SYMBOLS 11-271. GENERAL. The electrical and electronic symbols shown here are those that are likely to be encountered by the aviation maintenance technician. They are in accordance with ANSI-Y32.2-1975. 11-272. SYMBOLS. Only those symbols associated with aircraft electrical and electronic wiring have been listed in general. Refer to ANSI-Y32.2-1975 for more specific detail on each symbol. TABLE 11-27. Electronic/Electrical Symbols.
AC 43.13-1B 9/8/98 TABLE 11-27. Electronic/Electrical Symbols (continued).
9/8/98 AC 43.13-1B TABLE 11-27. Electronic/Electrical Symbols (continued).
AC 43.13-1B 9/8/98 TABLE 11-27. Electronic/Electrical Symbols (continued).
9/27/01 AC 43.13-1B CHG 1 TABLE 11-27. Electronic/Electrical Symbols (continued).
AC 43.13-1B CHG 1 9/27/01 TABLE 11-27. Electronic/Electrical Symbols (continued).
9/8/98 AC 43.13-1B TABLE 11-27. Electronic/Electrical Symbols (continued).
AC 43.13-1B 9/8/98 TABLE 11-27. Electronic/Electrical Symbols (continued).
9/8/98 AC 43.13-1B TABLE 11-27. Electronic/Electrical Symbols (continued).
AC 43.13-1B 9/8/98 TABLE 11-27. Electronic/Electrical Symbols (continued).
9/8/98 AC 43.13-1B TABLE 11-27. Electronic/Electrical Symbols (continued).
AC 43.13-1B 9/8/98 TABLE 11-27. Electronic/Electrical Symbols (continued).
9/8/98 AC 43.13-1B TABLE 11-27. Electronic/Electrical Symbols (continued).
AC 43.13-1B 9/8/98 Integrated Circuit Amplifiers Logic Gates Diode Transistor Symbols 11-273. 11-283. [RESERVED.
