TO 1-1-700 - Robins Air Force Base

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TO 1-1-700 vulnerable surfaces clean while the components are operating. In storage, however, the intrusion of contaminates can cause corrosion to continue unchecked until the component is ruined. Table 8-1 lists common effects of corrosion on electrical components and systems. 8.5.1.3 Electronic. Electronic systems are particularly vulnerable to corrosion damage. In modern electronics, circuit areas are minimized to permit fast operation. Because of this, most circuit paths have a very small cross-sectional area, making them extremely vulnerable to corrosion damage. Often, corrosion that is barely visible to the naked eye is severe enough to impact the operation of a circuit and cause a system failure. Table 8-1. Effects of Corrosion on Electronic Equipment Component Failure Mode Antennas Relay and switching systems Plugs, connectors, jacks Power cables Display lamps Waveguides Printed circuit boards Batteries Bus bars Coaxial Lines Shorts, changes is circuit constants, structural deterioration Mechanical failure, shorts, intermittent operation, signal loss Shorts, increased resistance, intermittent operation, water seal deterioration Disintegration of insulation, wire and connector deterioration, shorts Intermittent operation, electrical failures Loss of integrity against moisture, pitting, reduction of efficiency, structural deterioration Shorts, increased resistance, component and system failures High terminal resistance, contact point failure, structural damage to mounting Structural and electrical failures Impedance fluctuations, signal loss, deterioration of connectors 8.5.2 Recognizing Corrosion. The ability to recognize corrosion is essential to performing a comprehensive corrosion inspection. Metals tend to return to their natural forms (oxides, carbonates, and others) and are thus vulnerable to corrosion. Table 8-2 describes the application of common metals in communications electronics and the indicators of corrosion in those metals. Detailed instructions or guidelines for recognizing corrosion can be found in Chapter 9 of this manual. In most cases, deterioration of nonmetallic components allows moisture intrusion. This contributes to mechanical failure through swelling and cracking. In addition, it contributes to the alteration of the electronic characteristics of electronic components. Table 8-3 describes the type of attack and the appearance of the deterioration for common nonmetallic items in C-E-M equipment. 8.5.3 Effects of Solder Flux. Solder flux residues are highly corrosive and may be conductive as well. In addition, they have adhesive properties, attracting and accumulating dirt or other contaminates. In turn, these contaminates may trap moisture, causing corrosion or circuit failure. Ultraviolet light may be used to detect solder flux residue. 8.5.4 Effects of Microbial Presence. Bacteria and fungi can feed on organic material (encapsulants, conformal coatings, gaskets, thermoplastics, etc.). Some can release an acid which facilitates additional corrosion. The presence of these microbes can be identified by damp, slimy, and bad-smelling growths on the components in question. 8.5.5 Effects of Insect and Animal Presence. Insects and small animals can also feed on some organic compounds. In addition, they can build nests which will trap moisture. The presence of insects or animals can be identified by the presence of nests, holes in packaging, and excrement. 8.5.6 Inspection Procedures. This paragraph provides brief guidance with respect to corrosion inspections of communications electronics equipment. For more detailed information, see Chapter 9 of this manual. 8.5.6.1 General. Frequent corrosion inspections are essential to minimizing and treating corrosion damage to electronic equipment. Early detection minimizes the cost of repairing corrosion damage. 8-4
TO 1-1-700 8.5.6.2 Water Intrusion. Technicians should inspect the interior or shelters or enclosures frequently for evidence of water intrusion. Water intrusion will always lead to corrosion. Any evidence of water intrusion or corrosion should be reported so that the appropriate corrective action can be scheduled. The following steps can be used to locate the source of water intrusion: MIL-A-46146, ADHESIVE/SEALANT, SILICONE RTV, NON-CORROSIVE, GROUP I/II/III, TYPE I OR GROUP I, TYPE II 19 a. Verify installation of fasteners. Replace all damaged fasteners. b. Inspect form-in-place gaskets. Repair or replace as appropriate. c. Verify that all drains are open and operational. d. Prepare compartment with “witness material” such as blotter paper or paper towels. MIL-PRF-81733, SEALING AND COATING COMPOUND, CORROSION INHIBITIVE 48 i. If leaks are present, they are to be sealed with MIL-A- 46146 or MIL-PRF-81733. If the area is in contact with fluids (coolant, fuel, hydraulic oil), use MIL-PRF- 81733. e. Secure all external openings (doors, air intakes, etc.). f. If fresh water is available, apply water to the exterior of the shelter or enclosure for approximately 5 minutes. g. Allow 3 to 5 minutes for the water to drain. h. Open shelter and examine witness material for signs of water. MIL-PRF-81309, LUBRICANT, CORROSION PREVEN- TIVE COMPOUND 46 j. Apply MIL-PRF-81309 to fastener threads as appropriate. k. Repeat steps d through j until all leaks are located and eliminated. Table 8-2. Materials, Their Electronic Applications, and Corrosion Symptoms Material Typical Applications Corrosion Symptoms Iron and Steel Stainless Steel Aluminum Iron and steel are used for magnetic shields, component leads, transformer cores, brackets, racks, and general hardware. The iron or steel is usually plated with nickel, tin, or cadmium. Stainless steel is used for brackets, shelves, and mounting hardware. Stainless steel does not corrode in most situations. However, exposure to saltwater can cause pitting. Although stainless steel resists corrosion well, it is susceptible to crevice corrosion. Aluminum is used primarily for structural or housing purposes in electronics. When cleaning corrosion from metallic surfaces, it is essential to remove all corrosion product from adjacent structures. This is because corrosion products of other metals can be corrosive to aluminum. Corrosion on iron and steel is easily recognized because it produces red or black rust. The corrosion product of stainless steel is a roughened surface with a red, brown, or black stain. The corrosion product of aluminum is a white or grey powdery material. The presence of a painted coating is not an indicator that the metal is free of corrosion. Corrosion can occur under the topcoat, eventually causing blisters, flakes, chips, or bumps in the painted surface. 8-5
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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
Page 81 and 82: TO 1-1-700 CHAPTER 6 MOISTURE AND F
Page 83 and 84: TO 1-1-700 c. 6.2.6 Felt. Examine f
Page 85 and 86: TO 1-1-700 a. After first directing
Page 87: TO 1-1-700 6.4.5.14 Terminals, scre
Page 90 and 91: TO 1-1-700 NOTE • Authorized clea
Page 92 and 93: TO 1-1-700 Table 7-1. Cleaning of S
Page 102 and 103: TO 1-1-700 7.3.1.2.3 Portable, 45 g
Page 104 and 105: TO 1-1-700 Table 7-2. Common Milita
Page 106 and 107: TO 1-1-700 inactivity, storage, or
Page 108 and 109: TO 1-1-700 7.5.6.5.1 Grade 1 - A th
Page 110 and 111: TO 1-1-700 Table 7-4. Corrosion Pre
Page 112 and 113: TO 1-1-700 Table 7-5. Preservation
Page 114 and 115: 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 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
Page 152 and 153: TO 1-1-700 Table 8-5. Accessories o
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 166 and 167: TO 1-1-700 a. For bonding/grounding
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
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TO 1-1-700 f. Shield equipment from
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TO 1-1-700 b. Use e-inch rivnuts of
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TO 1-1-700 10.17.3 If the plating s
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TO 1-1-700 Figure 10-16. Dissipatio
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TO 1-1-700 (2) If allowable damage
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TO 1-1-700 Table 11-1. Recommended
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TO 1-1-700 11.6 3M CO. SCOTCH-BRITE
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TO 1-1-700 11.11.2 Control of Mecha
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TO 1-1-700 11.12.2 Mechanical Damag
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TO 1-1-700 MIL-DTL-81706 (ALODINE),
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TO 1-1-700 11.13.2.3 Application of
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TO 1-1-700 only when there is no da
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TO 1-1-700 NOTE SEMCO PASA-JELL 101
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TO 1-1-700 (CRES), lead, ceramic, g
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TO 1-1-700 11.13.7.2 Treatment of C
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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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