TO 1-1-700 - Robins Air Force Base

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TO 1-1-700 a. For bonding/grounding connections that require fairly frequent disassembly, preserve the connection area by applying MIL-PRF-81309, Type III Corrosion Preventive Compound, followed by a coating of MIL-PRF- 16173, Grade 4 Corrosion Preventive Compound. TT-I-735, ALCOHOL, ISOPROPYL 65 e. Wipe clean with a A-A-59323, Type II Cleaning Cloth, dampened with TT-I-735 Isopropyl Alcohol. f. Allow to air dry. g. For magnesium or aluminum alloys, treat the bare metal surface with chemical conversion coating material as described in Chapter 7 of this manual. TT-I-735, ALCOHOL, ISOPROPYL 65 h. Clean bonding cable with an A-A-59323, Type II Cleaning Cloth dampened with TT-I-735 Isopropyl Alcohol. i. If necessary, use an A-A-3077 Typewriter Brush to scrub the strap until all corrosion products and contaminants are dislodged. j. Wipe clean with the solvent-dampened cloth and allow to air dry. 8.9.1.2 Preservation. Preservation methods should be used following corrosion cleaning and removal. 8.9.1.3 Application. Apply MIL-PRF-81309 Water-Displacing Corrosion Preventive Compound, according to Table 8-7. The following procedures apply for bonding/grounding connections that are not environmentally protected continually. MIL-PRF-81309, LUBRICANT, CORROSION PREVENTIVE COMPOUND 46 MIL-PRF-16173, COMPOUND, CORROSION PREVENTIVE 37 MIL-PRF-8516, TYPE II, SEALING COMPOUND, POLYSULFIDE RUBBER 49 b. For connections that seldom require disassembly, preserve with the more permanent and abrasion-resistant MIL-PRF-8516, Type II Sealing Compound, applied with a spatula. 8.9.2 EMI Shielding. Electromagnetic energy that is generated/absorbed by communications electronics can interfere with systems causing malfunctions. This radiation, known as electromagnetic interference (EMI), is produced by radar antennas, electric motors, inadequately shielded circuits, etc. Some examples of EMI-related system malfunctions are microprocessor bit errors, computer memory loss, false indicators (i.e., alarms, lights, readouts), and power loss. In order to minimize EMI-induced failures, C-E-M housings must absorb and reflect incident electromagnetic energy. Usually the shielding system consists of a conductive gasket sandwiched between an aluminum alloy housing and an aluminum alloy lid. This gasket provides sufficient electrical conductivity across the enclosure/gasket/lid junction per military grounding/EMI shielding requirements. It also prevents fluid intrusion into the components. 8.9.2.1 Effects of Corrosion on EMI Shielding. Corrosion can degrade the electrical and mechanical properties of a joint. The exposure of EMI gaskets to various environmental conditions can significantly reduce its shielding effectiveness and service life. Under field service conditions, communications electronics experience corrosion between metal surfaces such as joints. In these environments, exclusion of electrolyte from the joint is essential to maintaining an EMI seal. Use of nonconductive environmental seals (gaskets, sealants, and coatings) must be used to exclude moisture from the joint. Corrosion-induced changes in bulk resistively of the EMI gasket may contribute to degradation of the EMI seal. 8.9.2.2 Addressing Corrosion. Corrosion issues need to be addressed to prevent the interference of the electrical and mechanical properties of an EMI shielding joint. This can be accomplished by performing an inspection followed by a corrosion treatment. 8.9.2.2.1 Inspection. EMI gaskets should be periodically checked to ensure they are continuing to provide their intended functions. Inspection intervals should balance the need for proper operation and the environment, with the 8-38
TO 1-1-700 destructiveness caused by surface wear of gaskets with disassembly/reassembly. Gaskets may deteriorate via attack by operational chemicals, corrosion, and wear. Therefore inspection should include the following: a. Check for corrosion products, pitting of the aluminum alloy surface, or bulges in the sealant due to corrosion beneath the gaskets. b. Check the bonding of the gasket to the structure to prevent moisture intrusion. c. Check for loss of electrical conductivity of the gasket or its electrical bond to the equipment. d. Check for wear and swelling of the gasket. e. Check for compression set of the seal. f. Check maintenance procedures are being followed (e.g. avoid solvents which can wash away conductive particles). g. Check for excessive bending and/or pulling of electrical cables and shields. 8.9.2.2.2 Treatment. Corrective maintenance of EMI gaskets depends on the type of gasket involved, size of the damaged area, and degree/type of corrosion. EMI gaskets are usually of either metal or conductive elastomer construction. Finger stock, mesh, and spiral ribbon are examples of metal gaskets. Conductive elastomers consist of dispersions of conductive particles (spheres, irregular shapes, fibers) in elastomer matrices. Oriented wire gaskets have characteristics of both categories. Since each type of EMI gasket has its own specificities, each will require special corrosion treatment/ repair. The following “generic” gasket repair procedure is outlined below for general guidance. Maintenance personnel should refer to the applicable equipment system specific technical manuals for more specific repair information. a. When corrosion is observed, disassemble only the affected area and remove the corrosion using the mildest available method. TT-I-735, ALCOHOL, ISOPROPYL 65 MIL-PRF-81309, LUBRICANT, CORROSION PREVEN- TIVE COMPOUND 46 b. Carefully clean the area with TT-I-735 Isopropyl Alcohol. If replacement seals are available, install them in accordance with aircraft maintenance instructions or bulletins. If replacement seals are not available or do not exist, spray the contacting surfaces with a light coating of MIL-PRF-81309, Type III and then reassemble. c. Inspect repairs and areas known to be chronic problems often. 8.9.3 ESD Sensitive Components. Very Large Scale Integration (VLSI) digital components are steadily increasing in functional power, speed, and system applications in military avionics. By making the VLSI devices small, less voltage is needed to operate circuitry and the noise immunity decreases. Many of these devices are highly susceptible to damage from the discharge of static electricity. Electrostatic discharge (ESD) affects many components such as transistors, resistors, integrated circuits and other types of semiconductor devices. A spark discharge resulting from the accumulation of electrostatic charges may not immediately destroy a device or cause it to become nonfunctional. The device can be permanently damaged, yet perform its intended function. Additional exposure to spark discharges or continued use of the device can further damage the item until failure occurs. This is known as a latent failure and can seriously affect a system's reliability. It is essential that everyone involved in the repair handling, transporting, and storing of electrostatic discharge sensitive (ESDS) items be concerned about ESD. All ESDS items should be packaged, shipped, and stored in ESD protective materials. Further information on the Air Force ESD program is contained in TO 00-25-234. 8.9.3.1 Effects of Corrosion. Corrosion can degrade the electrical and mechanical properties of ESD protection systems. The exposure of ESD devices/ESD protection systems to various environmental conditions can significantly increase their susceptibility to damage from the discharge of static electricity. Under field service conditions, military electronics experience corrosion between metal surfaces such as electrical bonding/grounding connections. This problem is two-fold. First, corrosion between metal surfaces in electronics creates structural weaknesses that undermine its effectiveness to shield ESDS components from induced potentials. Second, the corrosive process creates nonconductive products that decrease the paths of conduction of static charge away from the device or assembly. 8.9.3.2 Recommended Practices for Handling ESD Sensitive Components. ESD precautions are not limited to manufacturing or component repair personnel only. Anyone handling, processing, or using ESD devices must take precautionary steps. It would be futile for component repair personnel to take full precautions only to turn the repaired item over to technicians who ignore all precautions and inad- 8-39
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TO 1-1-700 TECHNICAL MANUAL CORROSI
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TO 1-1-700 TABLE OF CONTENTS Chapte
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TO 1-1-700 TABLE OF CONTENTS - CONT
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TO 1-1-700 LIST OF ILLUSTRATIONS -
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TO 1-1-700 FOREWORD 1. PURPOSE. The
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TO 1-1-700 List of Related Publicat
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TO 1-1-700 SAFETY SUMMARY 1. GENERA
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TO 1-1-700 AMS-G-6032, GREASE, PLUG
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TO 1-1-700 MIL-DTL-64159, COATING,
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TO 1-1-700 MIL-PRF-27617, GREASE, A
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TO 1-1-700 O-L-164, DRESSING, LEATH
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TO 1-1-700 MIL-T-81772, THINNER, PO
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TO 1-1-700 tronics equipment and th
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TO 1-1-700 cleaning situation, syst
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TO 1-1-700 c. Riveted joints shall
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TO 1-1-700 c. Remove and replace an
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TO 1-1-700 MIL-L-87177, LUBRICANT,
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TO 1-1-700 Figure 3-1. Simplified C
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TO 1-1-700 resistant, and also at t
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TO 1-1-700 is first noticeable as a
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TO 1-1-700 3.7.8 Oxygen Concentrati
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TO 1-1-700 Figure 3-14. Concentrati
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TO 1-1-700 Figure 3-17. Galvanic Se
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TO 1-1-700 Figure 3-20. Aluminum Su
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TO 1-1-700 3.8.7 CRES/Stainless Ste
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TO 1-1-700 3.9.10 Climate. Warm, mo
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TO 1-1-700 3.11 PREVENTATIVE MAINTE
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TO 1-1-700 CHAPTER 4 COMPOSITE AND
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TO 1-1-700 4.4.4.4 Glass parts shal
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TO 1-1-700 CHAPTER 5 PACKAGING (STO
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TO 1-1-700 extent of damage dependi
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TO 1-1-700 5.15 PRECAUTIONS FOR VCI
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TO 1-1-700 c. Secure the desiccant
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TO 1-1-700 Figure 5-8. Shock Isolat
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TO 1-1-700 Figure 5-9. Examples of
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TO 1-1-700 5.24.10 Rigid or Flexibl
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TO 1-1-700 CHAPTER 6 MOISTURE AND F
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TO 1-1-700 c. 6.2.6 Felt. Examine f
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TO 1-1-700 a. After first directing
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TO 1-1-700 6.4.5.14 Terminals, scre
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TO 1-1-700 NOTE • Authorized clea
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TO 1-1-700 Table 7-1. Cleaning of S
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TO 1-1-700 7.3.1.2.3 Portable, 45 g
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TO 1-1-700 Table 7-2. Common Milita
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TO 1-1-700 inactivity, storage, or
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TO 1-1-700 7.5.6.5.1 Grade 1 - A th
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TO 1-1-700 Table 7-4. Corrosion Pre
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TO 1-1-700 Table 7-5. Preservation
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TO 1-1-700 either case, MIL-PRF-269
Page 116 and 117: TO 1-1-700 MIL-PRF-85285, COATING,
Page 118 and 119: TO 1-1-700 c. Cadmium plated surfac
Page 120 and 121: TO 1-1-700 a. Scuff sand and feathe
Page 122 and 123: TO 1-1-700 7.7.7.2 If surface is no
Page 124 and 125: TO 1-1-700 7.7.9.2 Where only parti
Page 126 and 127: TO 1-1-700 7.8.1 Type I Application
Page 128 and 129: TO 1-1-700 Extend (Loctite) 32150 J
Page 130 and 131: TO 1-1-700 There are three ways to
Page 132 and 133: TO 1-1-700 vulnerable surfaces clea
Page 134 and 135: TO 1-1-700 Table 8-2. Materials, Th
Page 136 and 137: TO 1-1-700 Table 8-4. Electronic Cl
Page 150 and 151: TO 1-1-700 Table 8-5. Accessories o
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Page 154 and 155: TO 1-1-700 f. Devices with permanen
Page 156 and 157: TO 1-1-700 Table 8-7. Cleaning and
Page 158 and 159: TO 1-1-700 MIL-PRF-87937, CLEANING
Page 160 and 161: TO 1-1-700 of contamination). Maint
Page 162 and 163: TO 1-1-700 8.8.2 Protective Coating
Page 164 and 165: TO 1-1-700 • Tube clamps. • Min
Page 168 and 169: TO 1-1-700 vertently destroy the mo
Page 170 and 171: TO 1-1-700 doors, and other corrosi
Page 173 and 174: TO 1-1-700 CHAPTER 10 CORROSION PRO
Page 175 and 176: TO 1-1-700 MIL-PRF-81733, SEALING A
Page 177 and 178: TO 1-1-700 d. After corrosion is re
Page 179 and 180: TO 1-1-700 (3) Stainless/CRES steel
Page 181 and 182: TO 1-1-700 10.9 WATER ENTRAPMENT AR
Page 183 and 184: TO 1-1-700 f. Shield equipment from
Page 185 and 186: TO 1-1-700 b. Use e-inch rivnuts of
Page 187 and 188: TO 1-1-700 10.17.3 If the plating s
Page 189: TO 1-1-700 Figure 10-16. Dissipatio
Page 192 and 193: TO 1-1-700 (2) If allowable damage
Page 194 and 195: TO 1-1-700 Table 11-1. Recommended
Page 196 and 197: TO 1-1-700 11.6 3M CO. SCOTCH-BRITE
Page 198 and 199: TO 1-1-700 11.11.2 Control of Mecha
Page 200 and 201: TO 1-1-700 11.12.2 Mechanical Damag
Page 202 and 203: TO 1-1-700 MIL-DTL-81706 (ALODINE),
Page 204 and 205: TO 1-1-700 11.13.2.3 Application of
Page 206 and 207: TO 1-1-700 only when there is no da
Page 208 and 209: TO 1-1-700 NOTE SEMCO PASA-JELL 101
Page 210 and 211: TO 1-1-700 (CRES), lead, ceramic, g
Page 212 and 213: TO 1-1-700 11.13.7.2 Treatment of C
Page 214 and 215: TO 1-1-700 MIL-A-46106, ADHESIVE/SE
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TO 1-1-700 Table 12-1. Sealing Comp
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TO 1-1-700 used to apply sealants i
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TO 1-1-700 Figure 12-2. Sealant App
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TO 1-1-700 Figure 12-4. Rivet Appli
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TO 1-1-700 Figure 12-6. Sealant Inj
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TO 1-1-700 below and adhere very po
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TO 1-1-700 Table 12-2. Time Require
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TO 1-1-700 Table 12-2. Time Require
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TO 1-1-700 of 20 to 25 seconds in a
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TO 1-1-700 d. Remove all uncured se
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TO 1-1-700 MIL-PRF-81733, SEALING A
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TO 1-1-700 MIL-PRF-81733, SEALING A
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TO 1-1-700 Figure 12-12. Typical Me
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TO 1-1-700 may be used for low temp
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TO 1-1-700 Figure 12-14. Sealing Pr
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TO 1-1-700 - Robins Air Force Base

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