Par 11-167 Page 11-75 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. Splicing of individual wires in a group or bundle should have engineering approval and the splice(s) should be located to allow periodic inspection.
b. Many types of aircraft splice connectors are available for use when splicing individual wires. Use of a self-insulated splice connector is preferred; however, an uninsulated splice connector may be used, provided the splice is covered with plastic sleeving that is secured at both ends. Environmentally sealed splices that conform to MIL-T-7928 provide a reliable means of splicing in SWAMP areas. However, an uninsulated splice connector may be used, provided the splice is covered with dual wall shrink sleeving of a suitable material.
c. There should not be more than one splice in any one wire segment between any two connectors or other disconnect points, except: when attaching to the spare pigtail lead of a potted connector, to splice multiple wires to a single wire, to adjust wire size to fit connector contact crimp barrel size, and to make an approved repair. (Refer to MIL-W-5088, now SAE AS50881A, and NAVAIR 01-1A-505.)
d. Spl ices in bundles must be staggered so as to minimize any increase in the size of the bundle, preventing the bundle from fitting into its designated space, or cause congestion that will adversely affect maintenance. (See Figure 11-18.)
e. Splices should not be used within 12 inches of a termination device, except for paragraph f below.
f. Splices may be used within 12 inches of a termination device when attaching to the pigtail spare lead of a potted termination device, or to splice multiple wires to a single wire, or to adjust the wire sizes so that they are compatible with the contact crimp barrel sizes.
g. Selection of proper crimping tool, see paragraph 11-178.
FIGURE 11-18. STAGGERED SPLICES IN WIRE BUNDLE 11 -168.–11-173. [RESERVED.]
Par 11-174 Page 11-76 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 wire-to-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.
(1) Current rating.
(2) Wire size (gauge) and insulation diameter.
(3) Conductor material compatibility.
(4) Stud size.
(5) Insulation material compatibility.
(6) Application environment.
(7) Solder/solderless.
(8) Pre-insulated crimp-type ring-tongue terminals are preferred. The strength, size, and supporting means of studs and binding posts, as well as the wire size, should be considered when determining the number of terminals to be attached to any one post. In high-temperature applications, the terminal temperature rating must be greater than the ambient temperature plus current related temperature rise. Use of nickel-plated terminals and of uninsulated terminals with high-temperature insulating sleeves should be considered. Terminal blocks should be provided with adequate electrical clearance or insulation strips between mounting hardware and conductive parts.
b. Terminal Strips. Wires are usually joined at terminal strips. A terminal strip fitted with barriers should be used to prevent the terminals on adjacent studs from contacting each other.
Studs should be anchored against rotation. When more than four terminals are to be connected together, a small metal bus should be mounted across two or more adjacent studs. In all cases, the current should be carried by the terminal contact surfaces and not by the stud itself. Defective studs should be replaced with studs of the same size and material since terminal strip studs of the smaller sizes may shear due to overtightening the nut. The replacement stud should be securely mounted in the terminal strip, and the terminal securing nut should be tight. Terminal strips should be mounted in such a manner that loose metallic objects cannot fall across the terminals or studs. It is good practice to provide at least one spare stud for future circuit expansion or in case a stud is broken. Terminal strips that provide connection of radio and electronic systems to the aircraft electrical system should be inspected for loose connections, metallic objects that may have fallen across the terminal strip, dirt and grease accumulation, etc. These type conditions can cause arcing which may result in a fire, or system failures.
Par 11-174 Page 11-77
c. Terminal Lugs. Wire terminal lugs should be used to connect wiring to terminal block studs or equipment terminal studs. No more than four terminal lugs or three terminal lugs and a bus bar should be connected to any one stud. Total number of terminal lugs per stud includes a common bus bar joining adjacent studs. Four terminal lugs plus a common bus bar thus are not permitted on one stud. Terminal lugs should be selected with a stud hole diameter that matches the diameter of the stud. However, when the terminal lugs attached to a stud vary in diameter, the greatest 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. Spacers or washers should not be used between the tongues of terminal lugs.
e. Aluminum Terminal Lugs. The aluminum terminal lugs conforming to AS70991 (AS25435, AS25436, and AS25438) should be crimped to aluminum wire only. The tongue of the aluminum terminal lugs, or the total number of tongues of aluminum terminal lugs when stacked, should be sandwiched between two MS25440-5 flat washers when terminated on terminal studs. Spacers or washers should not be used between the tongues of terminal lugs.
Special attention should be given to aluminum wire and cable installations to guard against conditions that would result in excessive voltage drop and high resistance at junctions that may ultimately lead to failure of the junction. Examples of such conditions are improper installation of terminals and washers, improper torsion (“torquing” of nuts), and inadequate terminal contact areas.
f. Class 2 Terminal Lugs. The Class 2 terminal lugs conforming to MIL-T-7928 may be used for installation, provided that in such installations, Class 1 terminal lugs are adequate for replacement without rework of installation or terminal lugs. Class 2 terminal lugs should be the insulated type, unless the conductor temperature exceeds 105 °C. In that case, uninsulated terminal lugs should be used. Parts lists should indicate the appropriate Class 1 terminal lugs to be used for service replacement of any Class 2 terminal lugs installed.
g. Termination of Shielded Wire. For termination of shielded wire, refer to MIL-DTL-27500.
11-175. ATTACHMENT OF TERMINALS TO STUDS. Connectors and terminals in aircraft require special attention to ensure a safe and satisfactory installation. Every possibility of short circuits, due to improper installation, poor maintenance, and service life, should be addressed in the design. Electrical equipment malfunction has frequently been traced to poor terminal connections at terminal boards. Loose, dirty, or corroded contact surfaces can produce localized heating that may ignite nearby combustible materials or overheat adjacent wire insulation. (See paragraph 11-178.)
11-176. STUDS AND INSULATORS. The following recommendations concerning studs also apply to other feed-through conductors.
Par 11-176 Page 11-78
a. Current Carrying Stud Resistance. Due to heat loss arising from wire-to-lug and lug-to-stud voltage drop, the resistance per unit length of a current carrying stud should not be greater than that of the wire.
b. Size of Studs. In designing the stud for a feed-through connection, attention should be given to the higher resistance of brass, as compared to copper. A suggested method of determining the size is to use a current density in the stud equivalent to that of the wire, compensating for the difference of resistance of the metals. Consideration should also be given to mechanical strength.
c. Support for Studs. The main stud support in the feed-through insulation should be independent of the attachment of the lugs to the stud. Therefore, loosening of the insulation support of the stud will not affect the 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., are normally found in the manufacturer’s maintenance instruction manual.
e. Feed-Through Insulator and Stud Design. Feed-through insulator design should be such as to prevent a loose insulator from failing to provide circuit isolation. It should not be able to move from between the stud and the structure, thus allowing the two to come into contact. The assembly should be so designed that it is impossible to inadvertently misassemble the parts so that faults will result. Also, it is desirable to provide means to prevent the feed-through stud from turning while tightening the connection.
11-177. WIRE TERMINALS AND BINDING POSTS. All wire terminals in or on electrical equipment, except case ground, must be firmly held together with two nuts or suitable locking provisions, or should be secured in a positive manner to equipment in such a way that no insulation material is involved in maintaining physical pressure between the various current carrying members of an electrical connection. Terminal studs or binding posts should be of a size that is entirely adequate for the current requirements of the equipment and have sufficient mechanical strength to withstand the torque required to attach the cable to the equipment. All terminals on equipment should have barriers and covers provided by equipment manufacturers.
11-178. CRIMP ON TERMINAL LUGS AND SPLICES (pre-insulated crimp type). The crimp on terminal lugs and splices must be installed using a high-quality, ratchet-type crimping tool. We recommend the use of the proper calibrated tool. Aircraft quality crimp tools are manufactured to standards. Such tools are provided with positioners for the wire size and are adjusted for each wire size. It is essential that the crimp depth be appropriate for each wire size.
If the crimp is too deep or not deep enough, it may break or cut individual strands, or it may not be tight enough to retain the wire in the terminal or connector. Crimps that are not tight enough are also susceptible to high resistance due to corrosion build-up between the crimped terminal
Par 11-178 Page 11-79 and the wire. MIL-C-22520/2 or MIL-DTL-2250 specification covers in detail the general requirement for crimp tools, inspection gages, and tool kits.
a. Hand, portable, and stationary power tools are available for crimping terminal lugs.
These tools crimp the barrel to the conductor, and simultaneously from the insulation support to the wire insulation.
b. Crimp tools must be carefully inspected:
(1) Ensure that the full cycle ratchet mechanism is tamper-proof so that it cannot be disengaged prior to or during the crimp cycle.
(2) If the tool does not function or faults are found, reject the tool and send the tool to be repaired.
(3) The tool calibration and adjustments are made only by the manufacturer or an approved calibration laboratory.
(4) Suitable gages of the Go/No Go type are available and shall be used prior to 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. A plain nut with a spring lock washer and a plain washer may be used to provide binding and contact pressure.
11-180. –11- 184. [RESERVED.]
Par 11-185 Page 11-80 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. This section provides an overview of the principles involved in the design and maintenance of electrical bonding and grounding. SAE ARP1870 provides for more complete detailed information on grounding and bonding, and the application of related hardware.
11-186. GROUNDING. Grounding is the process of electrically connecting conductive objects to either a conductive structure or some other conductive return path for the purpose of safely completing either a normal or fault circuit.
a. Types of Grounding. If wires carrying return currents from different types of sources, such as signals of DC and AC generators, are connected to the same ground point or have a common connection in the return paths, an interaction of the currents will occur. Mixing return currents from various sources should be avoided because noise will be coupled from one source to another and can be a major problem for digital systems. To minimize the interaction between various return currents, different types of grounds should be identified and used. As a minimum, the design should use three ground types: (1) AC returns, (2) DC returns, and (3) all others. For distributed power systems, the power return point for an alternative power source would be separated. For example, in a two-AC generator (one on the right side and the other on the left side) system, if the right AC generator were supplying backup power to equipment located in the left side, (left equipment rack) the backup AC ground return should be labeled “AC Right.” The return currents for the left generator should be connected to a ground point labeled “AC Left.”
b. Current Return Paths. The design of the ground return circuit should be given as much attention as the other leads of a circuit. A requirement for proper ground connections is that they maintain an impedance that is essentially constant. Ground return circuits should have a current rating and voltage drop adequate for satisfactory operation of the connected electrical and electronic equipment. EMI problems, that can be caused by a system’s power wire, can be reduced substantially by locating the associated ground return near the origin of the power wiring
(e.g., circuit breaker panel) and routing the power wire and its ground return in a twisted pair.
Special care should be exercised to ensure replacement on ground return leads. The use of numbered insulated wire leads instead of bare grounding jumpers may aid in this respect. In general, equipment items should have an external ground connection, even when internally grounded. Direct connections to a magnesium (which may create a fire hazard) structure must not be used for ground return.
c. Heavy-Current Grounds. Power ground connections, for generators, transformer rectifiers, batteries, external power receptacles, and other heavy-current, loads must be attached to individual grounding brackets that are attached to aircraft structure with a proper metal-to-metal bonding attachment. This attachment and the surrounding structure must provide adequate conductivity to accommodate normal and fault currents of the system without creating excessive voltage drop or damage to the structure. At least three fasteners, located in a triangular or rectangular pattern, must be used to secure such brackets in order to minimize susceptibility to
Par 11-186 Page 11-81 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. Power return or fault current ground connections within flammable vapor areas must be avoided. If they must be made, make sure these connections will not arc, spark, or overheat under all possible current flow or mechanical failure conditions, including induced lightning currents. Criteria for inspection and maintenance to ensure continued airworthiness throughout the expected life of the aircraft should be established. Power return fault currents are normally the highest currents flowing in a structure. These can be the full generator current capacity. If full generator fault current flows through a localized region of the carbon fiber structure, major heating and failure can occur. CFC and other similar low-resistive materials must not be used in power return paths.
Additional voltage drops in the return path can cause voltage regulation problems. Likewise, repeated localized material heating by current surges can cause material degradation. Both problems may occur without warning and cause nonrepeatable failures or anomalies.
e. C ommon Ground Connections. The use of common ground connections for more than one circuit or function should be avoided except where it can be shown that related malfunctions that could affect more than one circuit will not result in a hazardous condition. Even when the loss of multiple systems does not, in itself, create a hazard, the effect of such failure can be quite distracting to the crew.
(1) Redundant systems are normally provided with the objective of assuring continued safe operation in the event of failure of a single channel and must therefore be grounded at well separated points. To avoid construction or maintenance errors that result in connecting such ground at a single point, wires that ground one channel of a redundant system should be incapable of reaching the ground attachment of the other channel.
(2) The use of loop type grounding systems (several ground leads connected in series with a ground to structure at each end) must be avoided on redundant systems, because the loss of either ground path will remain undetected, leaving both systems with a potential single-point failure.
(3) Electrical power sources must be grounded at separate locations on the aircraft structure. The loss of multiple sources of electrical power, as the result of corrosion of a ground connection or failure of the related fasteners, may result in the loss of multiple systems and should be avoided by making the ground attachments at separate locations.
(4) B onds to thermally or vibration isolated structure require special consideration to avoid single ground return to primary structure.
(5) The effect of the interconnection of the circuits when ungrounded should be considered whenever a common ground connection is used. This is particularly important when employing terminal junction grounding modules or other types of gang grounds that have a single attachment point.
Par 11-186 Page 11-82
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.
(4) Single point grounds for signal circuits, with such grounds being at the signal source, are often a good way to minimize the effects of EMI, lightning, and other sources of interference.
11-187. BONDING. The following bonding requirements must be considered:
a. Equipment Bonding. Low-impedance paths to aircraft structure are normally required for electronic equipment to provide radio frequency return circuits and for most electrical equipment to facilitate reduction in EMI. The cases of components which produce electromagnetic energy should be grounded to structure. To ensure proper operation of electronic equipment, it is particularly important to conform the system’s installation specification when interconnections, bonding, and grounding are being accomplished.
b. Metallic Surface Bonding. All conducting objects on the exterior of the airframe must be electrically connected to the airframe through mechanical joints, conductive hinges, or bond straps capable of conducting static charges and lightning strikes. Exceptions may be necessary for some objects such as antenna elements, whose function requires them to be electrically isolated from the airframe. Such items should be provided with an alternative means to conduct static charges and/or lightning currents, as appropriate.
c. Static Bonds. All isolated conducting parts inside and outside the aircraft, having an area greater than 3 in2 and a linear dimension over 3 inches, that are subjected to appreciable electrostatic charging due to precipitation, fluid, or air in motion, should have a mechanically secure electrical connection to the aircraft structure of sufficient conductivity to dissipate possible static charges. A resistance of less than 1 ohm when clean and dry will generally ensure such dissipation on larger objects. Higher resistances are permissible in connecting smaller objects to airframe structure.
11-188. BONDING INSPECTION. Inspect for the following:
a. If there is evidence of electrical arcing, check for intermittent electrical contact between conducting surfaces that may become a part of a ground plane or a current path. Arcing can be prevented either by bonding, or by insulation if bonding is not necessary.
b. The metallic conduit should be bonded to the aircraft structure at each terminating and break point. The conduit bonding strap should be located ahead of the piece of equipment that is connected to the cable wire inside the conduit.
Par 11-188 Page 11-83
c. Bond connections should be secure and free from corrosion.
d. Bonding jumpers should be installed in such a manner as not to interfere in any way with the operation of movable components of the aircraft.
e. Self-tapping screws should not be used for bonding purposes. Only standard threaded screws or bolts of appropriate size should be used.
f. Exposed conducting frames or parts of electrical or electronic equipment should have a low-resistance bond of less than 2.5 milliohms to structure. If the equipment design includes a ground terminal or pin, which is internally connected to such exposed parts, a ground wire connection to such terminal will satisfy this requirement. Refer to manufacturer’s instructions.
g. Bonds should be attached directly to the basic aircraft structure rather than through other bonded parts.
h. Bonds must be installed to ensure that the structure and equipment are electrically stable and free from the hazards of lightning, static discharge, electrical shock, etc. To ensure proper operation and suppression of radio interference from hazards, electrical bonding of equipment must conform to the manufacturer’s specifications.
i. Use of bonding testers is strongly recommended.
j. Measurements should be performed after the grounding and bonding mechanical connections are complete to determine if the measured resistance values meet the basic requirements. A high-quality test instrument (AN/USM-21A or equivalent) is required to accurately measure the very low-resistance values specified in this document. Another method of measurement is the millivolt drop test as shown in Figure 11-19.
k. U se appropriate washers when bonding aluminum or copper to dissimilar metallic structures so that any corrosion that may occur will be on the washer.
FIGURE 11-19. MILLIVOLT DROP TEST
Par 11-189 Page 11-84
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. To ensure a low-resistance connection, non-conducting finishes, such as paint and anodizing films, should be removed from the attachment surface to be contacted by the bonding terminal. On aluminum surfaces, a suitable conductive chemical surface treatment, known as chromate conversion coating, should be applied to the surfaces within 24 hours of the removal of the original finish. Refer to SAE ARP1870 for detailed instructions. Electric wiring should not be grounded directly to magnesium parts.
b. Corrosion Protection. One of the more frequent causes of failures in electrical system bonding and grounding is corrosion. Aircraft operating near salt water are particularly vulnerable to this failure mode. Because bonding and grounding connections may involve a variety of materials and finishes, it is important to protect completely against dissimilar metal corrosion.
The areas around completed connections should be post-finished in accordance with the original finish requirements or with some other suitable protective finish within 24 hours of the cleaning process. In applications exposed to salt spray environment, a suitable noncorrosive sealant, such as one conforming to AMSS8802F, should be used to seal dissimilar metals for protection from exposure to the atmosphere.
c. Corrosion Prevention. Electrolytic action may rapidly corrode a bonding connection if suitable precautions are not taken. Aluminum alloy jumpers are recommended for most cases;
however, copper jumpers should be used to bond together parts made of stainless steel, cadmium plated steel, copper, brass, or bronze. Where contact between dissimilar metals cannot be avoided, the choice of jumper and hardware should be such that corrosion is minimized, and the part likely to corrode would be the jumper or associated hardware. Tables 11-16 through 11-18 and Figures 11-20 through 11-22 show the proper hardware combinations for making a bond connection. At locations where finishes are removed, a protective finish should be applied to the completed connection to prevent subsequent corrosion.
TABLE 11-16. STUD BONDING OR GROUNDING TO FLAT SURFACE
SCREW OR BOLT - WASHER A LOCKWASHER E • STRUCTURE
WASHER B WASHER C
PLAIN NUT -
WASHER D (ERITTO T LOCKWASHER F LOCKNUT Aluminum Terminal and Jumper Screw or Lock Lock Bolt and Plain Washer Structure Washer A Washer B Washer Washer Lock Nut C&D E Nut Aluminum Cadmium Cadmium Aluminum Aluminum Cadmium Cadmium Cadmium Alloys Plated Plated Alloy Alloy Plated Plated Plated steel Steel Steel or Steel Steel Aluminum Magnesium Cadmium Cadmium Magnesium Magnesium Cadmium Cadmium Cadmium Alloys Plated Plated Alloy Alloy Plated Plated Plated Steel or Steel Steel Aluminum Steel, Cadmium Cadmium None None Cadmium Cadmium Cadmium Cadmium Plated Plated Plated Plated Plated Plated Steel Steel Steel or Steel Steel Aluminum Steel, Corrosion Cadmium None None Cadmium Corrosion Cadmium Corrosion Resisting Plated Plated Resist Plated Resisting Steel Steel Steel or Steel Steel Aluminum Tinned Copper Terminal and Jumper Aluminum Cadmium Cadmium Aluminum Aluminum Cadmium Cadmium Cadmium Alloys Plated Plated Alloy Alloy Plated Plated Plated Steel Steel Steel Steel Steel Magnesium Alloys' Steel, Cadmium Cadmium None None Cadmium Cadmium Cadmium Cadmium Plated Plated Plated Plated Plated Plated Steel Steel Steel Steel Steel Steel, Corrosion Corrosion None None Cadmium Corrosion Corrosion Corrosion Resisting Resisting Plated Resisting Resisting Resisting Steel Steel Steel Steel Steel ' Avoid connecting copper to magnesium.
Par 11-189 Page 11-85
TABLE 11-17. PLATE NUT BONDING OR GROUNDING TO FLAT SURFACE
LOCKWASHER
SCREW OR BOLT LIMITED TO 4
WASHER A
WASHER B
RIVET NUT PLATE Aluminum Terminal and Jumper Structure Screw or Bolt Rivet Lock Washer Washer A Washer B and Nut Plate Aluminum Cadmium Aluminum Cadmium Cadmium None Alloys Plated Steel Alloy Plated Steel Plated Steel or Aluminum Magnesium Cadmium Aluminum Cadmium Cadmium None or Alloys Plated Steel Alloy Plated Steel Plated Steel or Magnesium Aluminum Alloy Steel, Cadmium Cadmium Corrosion Cadmium Cadmium None Plated Plated Steel Resisting Steel Plated Steel Plated Steel or Aluminum Steel, Corrosion Corrosion Corrosion Cadmium Cadmium Cadmium Resisting Resisting Steel Resisting Steel Plated Steel Plated Steel or Plated Steel or Cadmium Aluminum Plated Steel Tinned Copper Terminal and Jumper Aluminum Cadmium Aluminum Cadmium Cadmium Aluminum?
Alloys Plated Steel Alloy Plated Steel Plated Steel Alloy Magnesium Alloys!
Steel, Cadmium Cadmium Corrosion Cadmium Cadmium None Plated Plated Steel Resisting Steel Plated Steel Plated Steel Steel, Corrosion Corrosion Corrosion Cadmium Cadmium None Resisting Resisting Steel Resisting Steel Plated Steel Plated Steel I Avoid connecting copper to magnesium.
2 Use washers having a conductive finished treated to prevent corrosion, suggest AN960JD10L.
Par 11-189 Page 11-86