Par 11-76 Page 11-516 STEP 4: Refer to the “altitude derating curve” of figure 11-6, look for sea level and 20,000 feet (on the abscissa) since these are the conditions at which the load will be carried. The wire must be derated by a factor of 1.0 and 0.91, respectively.
STEP 5: Derate the size #12 in a bundle rati ngs by multiplying 29.2 amps at sea level and 26.6 amps at 20,000 feet by 1.0 and 0.91, respectively, to obtained 29.2 amps and 23.8 amps. The total bundle capacity at sea level and 25 °C ambient is 29.2x12=350.4 amps. At 20,000 feet and 60 °C ambient the bundle capacity is 23.8x12=285.6 amps. Each size #12 wire can carry 29.2 amps at sea level, 25 °C ambient or 23.8 amps at 20,000 feet, 60 °C ambient.
STEP 6: Determine the actual circuit current for each wire in the bundle and for the bundle. If the values calculated in Step #5 are exceeded, select the next larger size wire and repeat the calculations.
11-70.11-75. [RESERVED.]
Par 11-76 Page 11-517 SECTION 6. AIRCRAFT ELECTRICAL WIRE SELECTION
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. Grounding connections for power, distribution equipment, and electromagnetic shielding must be given particular attention to ensure that electrical bonding resistance has not been significantly increased by the loosening of connections or corrosion.
Wire Size. Wires must have sufficient mechanical strength to allow for servi ce conditions. Do not exceed allowable voltage drop levels. Ensure that the wires are protected by system circuit protection devices, and that they meet circuit current ca rrying requirements. If it is desirable to use wire sizes smaller than #20, particular attention should be given to the mechanical strength and installation handling of these wires, e.g. vibration, flexing, and termination. When used in interconnecting airframe application, #24 gauge wire must be made of high strength alloy.
Installation Precautio ns for Small Wires. A s a general practice, wires smaller than size #20 must be provided with additional clamps, grouped with at least three other wires, and have additional support at terminations, such as connector grommets, strain-relief clamps, shrinkable sleeving, or telescoping bushings.
They should not be used in applications where they will be subjected to excessive vibration, repeated bending, or frequent disconnection from screw terminations.
Identification. All wire used on aircraft must have its type identification imprinted along its length. It is common practice to follow this part number with the five digit/letter C.A.G.E. code identifying the wire manufacturer. Existing installed wire that needs replacement can thereby be identified as to its performance capabilities, and the inadvertent use of a lower performance and unsuitable replacement wire avoided.
In addition to the type identification imprinted by the original wire manufacturer, aircraft wire also contains its unique circuit identification coding that is put on at the time of harness assembly. The traditional “Hot Stamp” method has not been totally satisfactory in recent years when used on modern, ultra-thinwalled installations. Fracture of the insulation wall and penetration to the conductor of these materials by the stamping dies have occurred.
Later in service, when these openings have been wetted by various fluids, serious arcing and surface tracking have damaged wire bundles.
Extreme care must be taken during circuit identification by a hot stamp machine on wire with a 10 mil wall or thinner. Alternative identification methods, such as “Laser Printing” and “Ink Jet,” are coming into increasing use by the industry. When such modern equipment is not available, the use of stamped identification sleeving should be considered on thin-walled wire, especially when insulation wall thickness falls below 10 mils.
AIRCRAFT WIRE MATERIALS. Only wire, specifically designed for airborne use, must be installed in aircraft.
Authentic Aircraft Wire. Most aircraft wire designs are to specifications that require manufacturers to pass rigorous testing of wires before being added to a Qualified Products List (Q PL) and being permitted to produce the wire. Aircraft manufacturers who maintain their own wire specifications invariably exercise close control on their approved
Par 11-78 Page 11-518 (and 11-38) 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.
Platings. Bare copper develops a surface oxide coating at a rate dependent on temperature. This oxide film is a poor conductor of electricity and inhibits retermination of wire. Therefore, all airc raft wiring has a coating of either tin, silver, or nick el, that have far slower oxidation rates.
Tin coated copper is a very common plating material. Its ability to be successfully soldered without highly active fluxes diminishes rapidly with time after manufacture. It can be used up to the limiting temperature of 150 °C.
Silver-coated wire is used where temperatures do not exceed 200 °C (392 °F).
Nickel coated wire retains its properties beyond 260 °C, but most aircraft wire using such coated strands have insulation systems that cannot exceed that temperature on longterm exposure. Soldered terminations of nickel-plated conductor require the use of different solder sleeves or flux than those used with tin or silver-plated conductor.
Conductor Stranding. Because of fli ght vibration and flexing, conductor round wire should be stranded to minimize fatigue breakage.
Wire Construction Versus Application. T h e m o s t important consideration in the selection of aircraft wire is properly matching the wire’s construction to the application environment. Wire construction that is suitable for the most severe environmental condition to be encountered should be selected. Wires are typica lly categorized as being suitable for either “open wiring” or “protected wiring” applications. MIL-W-5088L, Appendix A table A-I lists wires considered to have sufficient abrasion and cut-through resistance to be suitable for open-harness construction. MIL-W-5088L, Appendix A table A-II lists wires for protected app lications. These wires are not recommended for aircraft interconnection wiring unless the subject harness is covered throughout its length by a protective jacket . The wire temperature rating is typically a measure of the insulation’s ability to withstand the combination of ambient temperature and current related conductor temperature rise.
Insulations. There are many insulation materials and combinations used on aircra ft electrical wire. An explanation of many of the abbreviations are identified in the glossary.
SUBSTITUTIONS. In the repair and modification of existing aircraft, when a replacement wire is required, the maintenance manual for that aircraft must first be reviewed to determine if the original aircraft manufacturer (OAM) has approved any substitution. If not, then the OAM must be contacted for an acceptable replacement.
MIL-W-5088L Wiring, Aerospace Vehicle, Appendix A lists wire types that have been approved for military aerospace applications in open and protected wiring applications. These wires could potentially be used for substitution when approved by the OAM.
Areas designated as severe wind and moisture problem (SWAMP) areas differ
Par 11-78 Page 11-519 (and 11-38) 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. Wires for these applications often have design features incorporated into their construction that may make the wire uni que; therefore an acceptable substitution may be difficult, if not impossible, to find.
It is very important to use the wire type recommended in the aircraft manufacturer’s maintenance handbook.
The use of current military specification, multiconductor cables in place of OEM installed constructions may create problems such as color sequence. Some civilian aircraft are wired with the older color sequence employing “Red-Blue-Yellow” as the fi rst three colors. Current military specification, multi-conductor cables, in accordance with MIL-C- 27500, use “White-Blue- Orange” for the initial three colors. Use of an alternative color code during modification without adequate notation on wiring diagrams could severely complicate subsequent servici ng of the aircraft. At the time of this writing, MIL-C-27500 is being revised to include the older color sequence and could eliminate this problem in the future.
11-79.11-84. [RESERVED.]
Par 11-85 Page 11-520
SECTION 7. TABLE OF ACCEPTABLE WIRES
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.
All wires in tables 11-11 and 11-12 have been determined to meet the flammability requirements of Title 14 of the Code of Federal Regulation (14 CFR) part 25, section 25.869(a)(4) and the applicable portion of part 1 of Appendix F of part 25.
The absence of any wire from tables 11-11 and 11-12 are not to be construed as being unacceptable for use in aircraft. However, the listed wires have all been reviewed for such use and have been found suitable, or have a successful history of such usage.
Explanations of the various insulation materials mentioned in table 11-11, by abbreviations, can be found in the glossary.
OPEN AIRFRAME INTERCONNECTING WIRE.
Interconnecting wire is used in point to point open harnesses, normally in the interior or pressurized fuselage, with each wire providing enough insulation to resist damage from handling and service exposure. (See table 11-11.) Electrical wiring is often installed in aircraft without special enclosing means.
This practice is known as open wiring and offers the advantages of ease of maintenance and reduced weight.
PROTECTED WIRE. Airborne wire that is used within equipment boxes, or has additional protection, such as an exterior jacket, conduit, tray, or other covering is known as protected wire. (See table 11-12.)
SEVERE WIND AND MOISTURE PROBLEMS (SWAMP). Areas such as wheel wells, wing fold and pylons, flap areas, and those areas exposed to extended weather shall dictate selection and will require special consideration. Insulation or jacking will vary according to the environment. Suitable wire types selected from MIL-W-22759 shall be used in these applications. (See table 11-11.)
Suitable wire types selected from MIL-W-22759 are preferred for areas that require repeated bending and flexing of the wire. Consideration should be made to areas that require frequent component removal or repair.
(See table 11-11.)
SHIELDED WIRE. With the increase in number of highly sensitive electronic devices found on modern aircraft, it has become very important to ensure proper shielding for many electric circuits. Shielding is the process of applying a metallic covering to wiring and equipment to eliminate interference caused by stray electromagnetic energy. Shielded wire or cable is typically connected to the aircraft’s ground at both ends of the wire, or at connectors in the cable. Electromagnetic Interference (EMI) is caused when electromagnetic fields (radio waves) induce high-frequency (HF) voltages in a wire or component. The induced voltage can cause system inaccuracies or even failure, therefore putting the aircraft and passengers at risk. Shielding helps to eliminate EMI by protecting the primary conductor with an outer conductor. Refer to MIL-DTL-27500, Cable, Power, Electrical and Cable Special Purpose, Electrical Shielded and Unshielded General Specifications.
Par 11-85 Page 11-521 TABLE 11-11. Open Wiring.
Document Voltage rating (maximum) Rated wire temperature (°C) Insulation Type Conductor type MIL-W-22759/1 600 200 Fluoropolymer insulated TFE and TFE coated glass Silver coated copper MIL-W-22759/2 600 260 Fluoropolymer insulated TFE and TFE coated glass Nickel coated copper MIL-W-22759/3 600 260 Fluoropolymer insulated TFE -glass- TFE Nickel coated copper MIL-W-22759/4 600 200 Fluoropolymer insulated TFE -glass- FEP Silver coated copper MIL-W-22759/5 600 200 Fluoropolymer insulat ed extruded TFE Silver coated copper MIL-W-22759/6 600 260 Fluoropolymer insulated extruded TFE Nickel coated copper MIL-W-22759/7 600 200 Fluoropolymer insulat ed extruded TFE Silver coated copper MIL-W-22759/8 600 260 Fluoropolymer insulated extruded TFE Nickel coated copper MIL-W-22759/9 1000 200 Fluoropolymer insulat ed extruded TFE Silver coated copper MIL-W-22759/10 1000 260 Fluoropolymer insulated extruded TFE Nickel coated copper MIL-W-22759/13 600 135 Fluoropolymer insulated FEP PVF2 Tin coated copper, MIL-W-22759/16 600 150 Fluoropolymer insulated extruded ETFE Tin coated copper, MIL-W-22759/17 600 150 Fluoropolymer insulated extruded ETFE Silver coated high strength copper alloy MIL-W-22759/20 1000 200 Fluoropolymer insulated ex truded TFE Silver coated high strength copper alloy MIL-W-22759/21 1000 260 Fluoropolymer insulated extruded TFE Nickel coated high strength copper alloy MIL-W-22759/34 600 150 Fluoropolymer insulated crosslinked modified ETFE Tin coated copper MIL-W-22759/35 600 200 Fluoropolymer insulated crosslinked modified ETFE Silver coated high strength copper alloy MIL-W-22759/41 600 200 Fluoropolymer insulated crosslinked modified ETFE Nickel coated copper MIL-W-22759/42 600 200 Fluoropolymer insulated crosslinked modified ETFE Nickel coated high strength copper alloy MIL-W-22759/43 600 200 Fluoropolymer insulated crosslinked modified ETFE Silver coated copper MIL-W-25038/3/2/ 600 260 See specification sheet See specification sheet MIL-W-81044/6 600 150 Crosslinked polyalkene Tin coated copper MIL-W-81044/7 600 150 Crosslinked polya lkene Silver coated high strength copper alloy MIL-W-81044/9 600 150 Crosslinked polyalkene Tin coated copper MIL-W-81044/10 600 150 Crosslinked polya lkene Silver coated high strength copper alloy
Par 11-89 Page 11-522 (and 11-42) TABLE 11-12. Protected wiring.
Document Voltage rating (maximum) Rated wire temperature (°C) Insulation Type Conductor type MIL-W-22759/11 600 200 Fluoropolymer insula ted extruded TFE Silver coated copper MIL-W-22759/12 600 260 Fluoropolymer insulated extruded TFE Nickel coated copper MIL-W-22759/14 600 135 Fluoropolymer insulated FEP-PVF2 Tin coated copper MIL-W-22759/15 600 135 Fluoropolymer insulated F EP-PVF2 Silver plated high strength copper alloy MIL-W-22759/18 600 150 Fluoropolymer insulated extruded ETFE Tin coated copper MIL-W-22759/19 600 150 Fluoropolymer insulated extr uded ETFE Silver coated high strength copper alloy MIL-W-22759/22 600 200 Fluoropolymer insulated extr uded TFE Silver coated high strength copper alloy MIL-W-22759/23 600 260 Fluoropolymer insulated extruded TFE Nickel coated high strength copper alloy MIL-W-22759/32 600 150 Fluoropolymer insulated crosslinked modified ETFE Tin coated copper MIL-W-22759/33 600 200 Fluoropolymer insulated crosslinked modified ETFE Silver coated high strength copper alloy MIL-W-22759/44 600 200 Fluoropolymer insulated crosslinked modified ETFE Silver coated copper MIL-W-22759/45 600 200 Fluoropolymer insulated crosslinked modified ETFE Nickel coated copper MIL-W-22759/46 600 200 Fluoropolymer insulated crosslinked modified ETFE Nickel coated high strength copper alloy MIL-W-81044/12 600 150 Crosslinked polyalkene Tin coated copper MIL-W-81044/13 600 150 Crosslinked polyalkene Silver coated high strength copper alloy MIL-W-81381/17 600 200 Fluorocarbon polyi mide Silver coated copper MIL-W-81381/18 600 200 Fluorocarbon pol yimide Nickel coated copper MIL-W-81381/19 600 200 Fluorocarbon polyimide Silver coated high strength copper alloy MIL-W-81381/20 600 200 Fluorocarbon polyi mide Nickel coated high strength copper alloy MIL-W-81381/21 600 150 Fluorocarbon polyimide Tin coated copper
11-90.11-95. [RESERVED.]
Par 11-96 Page 11-523
SECTION 8. WIRING INSTALLATION INSPECTION REQUIREMENTS
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.
Accordingly, aircraft wiring must be visually inspected for the following requirements:
CAUTION: For personal safety, and to avoid the possibility of fire, turn off all electrical power prior to starting an inspection of the aircraft electrical system or performing maintenance.
Wires and cables are supported by suitable clamps, grommets, or other devices at intervals of not more than 24 inches, except when contained in troughs, ducts, or conduits. The supporting devices should be of a suitable size and type, with the wires and cables held securely in place without damage to the insulation.
Metal stand-offs must be used to maintain clearance between wires and structure. Employing tape or tubing is not acceptable as an alte rnative to stand-offs for maintaining clearance.
Phenolic blocks, plastic liners, or rubber grommets are installed in holes, bulkheads, floors, or structural members where it is impossible to install off-angle clamps to maintain wiring separation. In such cases, additional protection in the form of plastic or insulating tape may be used.
Wires and cables in junction boxes, panels, and bundles are properly supporte d and laced to provide proper grouping and routing.
Clamp retaining screws are properly secured so that the movement of wires and cables is restricted to the span between the points of support and not on soldered or mechanical connections at terminal posts or connectors.
Wire and cables are properly supported and bound so that there is no interference with other wires, cables, and equipment.
Wires and cables are adequately supported to prevent excessive movement in areas of high vibration.
Insulating tubing is secured by tying, tie straps or with clamps.
Continuous lacing (spaced 6 inches apart) is not used, except in panels and junction boxes where this practice is optional. When lacing is installed in this manner, outside junction boxe s should be removed and replaced with individual loops.
Do not use tapes (such as friction or plastic tape) which will dry out in service, produ ce chemical reactions with wire or cable insulation, or absorb moisture.
Insulating tubing must be kept at a minimum and must be used to protect wire and cable from abrasion, chafing, exposure to fluid, and other conditions which could affect the cable insulation. However; the use of insulating tubing for support of wires and cable in lieu of stand-offs is prohibited.
Do not use moisture-absorbent material as “fill” for clamps or adapters.
Ensure that wires and cables are not tied or fastened together in conduit or insulating tubing.
Ensure cable supports do not restrict the wires or cables in such a manner as to interfere with operation of equipment shock mounts.
Do not use tape, tie straps, or cord for primary support.
Make sure that drain holes are present in drip loops or in the lowest portion of tubing placed over the wiring.
Ensure that wires and cables are routed in such a manner that chafing will not occur against the airframe or other components.
Par 11-105 Page 11-524 (and 11-48) Ensure that wires and cables are positioned in such a manner that they are not likely to be used as handholds or as support for personal belongings and equipment.
Ensure that wires and cables are routed, insofar as practicable, so that they are not exposed to damage by personnel moving within the aircraft.
Ensure that wires and cables are located so as not to be susceptible to damage by the storage or shifting of cargo.
Ensure that wires and cables are routed so that there is not a possibility of damage from battery electrolytes or other corrosive fluids.
Ensure that wires and cables are adequately protected in wheel wells and other areas where they may be exposed to damage from impact of rocks, ice, mud, etc.
(If re-routing of wires or cables is not practical, protective jacketing may be installed). This type of installation must be held to a minimum.
Where practical, route wires and cables above fluid lines. Wires and cables routed within 6 inches of any flammable liquid, fuel, or oxygen line should be closely and rigidly supported. A minimum of 2 inches must be maintained between wiring and such lines or related equipment, except when the wiring is positively clamped to maintain at least 1/2-inch separation or when it must be connected di rectly to the fluid-carrying equipment.
Ensure that a trap or drip loop is provided to prevent fluids or condensed moisture from running into wires and cables dressed downward to a connector, terminal block, panel, or junction box.
Wires and cables installed in bilges and other locations where fluids may be trapped are routed as far from the lowest point as possible or otherwise provided with a moisture-proof covering.
Separate wires from high-temperature equipment, such as resistors, exhaust stacks, heating ducts, etc., to prevent insulation breakdown. Insulate wires that must run through hot areas with a high-temperature insulation material such as fiberglass or PTFE. Avoid hightemperature areas when usi ng cables having soft plastic insulation such as polyethylen e, because these materials are subject to deterioration and deformation at elevated temperatures. Many coaxial cables have this type of insulation.
The minimum radius of bends in wire groups or bundles must not be less than 10 times the outside diameter of the largest wire or cable, except that at the terminal strips where wires br eak out at terminations or reverse direction in a bundle. Where the wire is
Par 11-96 Page 11-525 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 is 20 times the diameter.
Ensure that RF cables, e.g., coaxial and triaxial, are bent at a radius of no less than 6 times the outside diameter of the cable.
Ensure that wires and cables, that are attached to assemblies where relative movement occurs (such as at hinges and rotating pieces; pa rticularly doors, control sticks, control wheels, columns, and flight control surfaces), are installed or pr otected in such a manner as to prevent deterioration of the wires and cables caused by the relative movement of the assembled parts.
Ensure that wires and electrical cables are separated from mechanical control cables. In no instance should wire be able to come clos er than 1/2 inch to such controls when light hand pressure is applied to wires or controls. In cases where clearance is less than this, adequate support must be provided to prevent chafing.
Ensure that wires and cables are provided with enough slack to meet the following requirements:
Permit ease of maintenance.
Prevent mechanical strain on the wires, cables, junctions, and supports.
Permit free movement of shock and vibration mounted equipment.
Allow shifting of equipment, as necessary, to perform alignment, servicing, tuning, removal of dust covers, and changing of internal components while installed in aircraft.
Ensure that unused wires are individually dead-ended, tied into a bundle, and secured to a permanent structure.
Each wire should have strands cut even with the insulation and a pre-insulated closed end connector or a 1-inch piece of insulating tubing placed over the wire with its end folded back and tied.
Ensure that all wires and cables are identified properly at intervals of not more than 15 inches.
Coaxial cables are identified at both equipment ends.
WIRING REPLACEMENT. Wiring must be replaced with equivalent wire (see paragraph 11-78) when found to have any of the following defects:
Wiring that has been subjected to chafing or fraying, that has been severely damaged, or that primary insulation is suspected of being penetrated.
Wiring on which the outer insulation is brittle to the point that slight flexing causes it to crack.
Wiring having weather-cracked outer insulation.
Wiring that is known to have been exposed to electrolyte or on which the insulation appears to be, or is suspected of being, in an initial stage of deterioration due to the effects of electrolyte.
Par 11-96 Page 11-526 Check wiring that shows evidence of overheating (even if only to a minor degree) for the cause of the overheating.
Wiring on which the insulation has become saturated with engine oil, hydraulic fluid, or another lubricant.
Wiring that bears evidence of having been crushed or severely kinked.
Shielded wiring on which the metallic shield is frayed and/or corroded. Cleaning agents or preservatives should not be used to minimize the effects of corrosion or deterioration of wire shields.
Wiring showing evidence of breaks, cracks, dirt, or moisture in the plastic sleeves placed over wire splices or terminal lugs.
Sections of wire in which splices occur at less than 10-foot intervals, unless specifically authorized, due to parallel connections, locations, or inaccessibility.
When replacing wiring or coaxial cables, identify them properly at both equipment power source ends.
Testing of the electrical and chemical integrity of the insulation of sample wires taken from areas of the aircraft that have experienced wiring problems in the past, can be used to supplement visual examination of the wire. The test for chemical integrity should be specific for the degradation mode of the insulation. If the samples fail either the electrical or chemical integrity tests, then the wiring in the area surrounding the sampling area is a candidate for replacement.
TERMINALS AND TERMINAL BLOCKS. Inspect to ensure that the following installation requirements are met:
Insulating tubing is placed over terminals (except preinsulated types) to provide electrical protection and mechanical support and is secured to prevent slippage of the tubing from the terminal.
Terminal module blocks are securely mounted and provided with adequate electrical clearances or insulation strips between mounting hardware and conductive parts, except when the terminal block is used for grounding purposes.
Terminal connections to terminal module block studs and nuts on unused studs are tight.
Evidence of overheating and corrosion is not present on connections to terminal module block studs.
Physical damage to studs, stud threads, and terminal module blocks is not evident. Replace cracked terminal strips and those studs with stripped threads.
The number of terminal connections to a terminal block stud does not exceed four, unless specifically authorized.
Shielding should be dead-ended with suitable insulated terminals.
All wires, terminal blocks, and individual studs are clearly identified to correspond to aircraft wiring manuals.
Terminations should be made using terminals of the proper size and the appropriate terminal crimping tools.
FUSES AND FUSE HOLDERS. Inspect as follows:
Check security of connections to fuse holders.
Par 11-99 Page 11-527 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.
Check mounting security of fuse holder.
Inspect for replenishment of spare fuses used in flight.
Replace with fuses of appropriate current rating only.
Inspect for exposed fuses susceptible to shorting.
Install cover of nonconducting material if required.
CONNECTORS. Ensure reliability of connectors by verifying that the following conditions are met or that repairs are effected as required.
Inspect connectors for security and evidence of overheating (cause of over-heating must be corrected), and exteriors for corrosion and cracks. Also, wires leading to connectors must be inspected for deterioration due to overh eating. Replace corroded connections and overheated connectors.
Ensure installation of cable clamp (reference MIL-C-85049) adapters on applicable MS connectors, except those that are moisture-proof.
See that silicone tape is wrapped around wires in MS3057 cable clamp adapters so that tightening of the cable clamp adapter cap provi des sufficient grip on the wires to keep tension from being applied to the connector pins.
Make sure unused plugs and receptacles are covered to prevent inclusion of dust and moisture. Receptacles should have metal or composite dust caps attached by their normal mating method. Plugs may have a dust cap similar to above or have a piece of polyolefin shrink sleeving shrunk over the connector, starting from th e backshell th reads, with a tail sufficiently long enough to doubleback over the connector and be tied with polyester lacing tape behind the coupling nut. The cable identification label should be visible behind the connector or a tag should be attached identifying the associ ated circuit or attaching equipment. The connector should be attached to structure by its normal mounting means or by the use of appropriate clamps.
Ensure that connectors are fully mated by checking position and tightness of coupling ring or its alignment with fully mated indicator line on receptacle, if applicable.
Ensure that the coupling nut of MS connectors is safetied, by wire or other m echanical locking means, as required by applicable aircraft instructional manuals.
Ensure that moisture-absorbent material is not used as “fill” for MS3057 clamps or adapters.
Ensure that there is no evidence of deterioration such as cracking, missing, or disintegration of the potting material.
Identical connectors in adjacent locati ons can lead to incorrect connections. When such installations are unavoidable, the attached wiring must be clearly identified and must be routed and clamped so that it cannot be mismatched.
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.