Appendix 3 Minimum Failure Free Lifetime (MFL) The minimum period of time that an avionics system, subsystem, module, or component performs satisfactorily without failure.
Nitrates Compounds including certain combinations of nitrogen and oxygen. Present in many industrial pollutants.
Noble Metal A metal usually found as uncombined metal in nature. Platinum, gold, and silver are noble metals.
Noncritical Avionics Components Components such as tube sockets, mechanical devices, knobs, and hardware.
Non-Destructive Inspection A method used to check the soundness of a material or a part without diminishing the strength, value, quality, or serviceability of the part.
Organic Coating A coating composed of matter derived from living organisms or carbon-based compounds
(i.e., paint, plastic, grease, preservative).
Outgassing Emission of a gas during the cure or decomposition of organic material. Usually increases with a rise in temperature.
Passivation The process or processes that cause a metal to become inert in a given corrosive environment.
pH A measure of hydrogen ions in concentration of a solution (pH 7 is neutral; below 7 is acidic;
above 7 is basic or alkaline).
Phantom Gripe An intermittent malfunction or failure which cannot be verified, identified, or duplicated for corrective action.
Pitting A form of corrosion that develops in highly localized areas of a metal surface that is not attacked elsewhere to any great extent. This corrosion attack results in the development of cavities or pits.
Pits may vary from deep cavities of small diameter to relatively shallow depressions.
Plasticizer A chemical added to rubber or resins to impart flexibility.
Appendix 3 Polyethylene A thermal plastic (softens when heated) characterized by its high impact strength, high electrical resistively, nontoxicity, and combustibility. One of several plastics used in wire coating.
Potting Compound A rubber-like material, usually poured, which cures to a hard consistency and provides moisture and vibration resistance to the item.
Primer Coat The first coat of a protective paint system. Improves adhesion of the succeeding topcoat and usually contains a corrosion inhibitor.
Reduction Reaction Gain of electrons by a constituent of a chemical reaction.
Relative Humidity The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage.
Reversion The situation wherein a cured material reverts toward its original pre-cured condition, (e.g., a cured potting compound that reverts to a sticky, liquid-like consistency).
Stress Force divided by cross-sectional area.
Symbols The following definitions apply to warnings, cautions, and notes found throughout this advisory circular (AC):
WARNING: An operation or maintenance procedure, practice, condition, statement, etc., which if not strictly observed, could result in injury to or death of personnel or long term (chronic) health hazards to personnel.
CAUTION: An operation or maintenance procedure, practice, condition, statement, etc., which if not strictly observed, could result in damage or destruction of equipment or loss of mission effectiveness.
NOTE: An operating procedure, practice, or condition, etc., which is essential to emphasize.
Tensile Strength Stress at which a material fails.
Total Environment The circumstances and conditions which surround and influence the equipment. The total environment includes manufacturing, handling, storage, shipping, mission, maintenance, and repair.
Appendix 3 Ultraviolet Light Light in a wavelength band ranging from the invisible wavelengths of about 4 nanometers (nm) to the border of the x-ray region at about 380 nm, just beyond the violet end of the visible spectrum.
Unacceptable Response A detrimental abnormality in system performance.
Undesirable Response A tolerated interruption of normal performance.
Wicking See Capillary Action.
Index
COMPREHENSIVE INDEX
SUBJECT PAGE A Abrasive Tools ......................................................................................................... 51, 53, 74, 95, 96
Aircraft Cleaning Compound Method184
Air Drying62
Alternate Cleaning Methods183
Aluminum ............................................................................. 8, 18, 32, 33, 34, 75, 121, 151, 163, 173
Aluminum Electrolytic Capacitors138
Aluminum Surface Treatment75
Anode ................................................................................................................................... 5, 17, 148
Definition5
Antenna Connectors ............................................................................................................... 120, 121
Antenna Mounting Area Preparation Procedures111
Antenna Systems ...................................................................................................................... 24, 111
Application of Coatings80
Application of Primer80
Application of Topcoat83
Aqueous Ultrasonic Cleaner52
ATE Cabinets, Doors, and Panels125
Atom5
Avionics Cleaning Equipment50
Avionics Cleaning Materials47
Avionics Cleaning Procedures54
Cleaning and Drying Restrictions ........................................................................................ 55, 56
Cleaning and Removal of Bacteria and Fungi58
Cleaning and Removal of Dust, Dirt, Grease, and Oil58
Cleaning and Removal of Silicone Lubricant .................................................................... 58, 130 Cleaning and Removal of Solder Flux Residue ....................................................... 37, 48, 57, 98
Fingerprint Removal57
Hand Cleaning Methods56
Hazardous Chemical or Material Identification Label ................................................... 49, 50, 73
Avionics Cleaning Equipment50
Cleaning Procedures54
Corrosion Cleaning Facility45
Hazards of Cleaning54
Materials Used for Cleaning46
Post-cleaning Procedures61
Pre-cleaning Criteria55
Solvent Ultrasonic Cleaner .......................................................................................... 53, 63, 127 Special Considerations ......................................................................................................... 26, 61 Surface Preparation ...................................................................................................... 59, 78, 149
Water Base Solvent Spray Booth51
When To Clean54
Avionics Test Equipment124
Index B
Basic ESD Precautions176
Battery Compartment ....................................................................................................... 21, 100, 126
Battery Compartments, Boxes, and Adjacent Areas100
Beryllium Copper163-168
Bilge Areas ........................................................................................................................... 21, 39, 99
Bimetallic Junctions148
Black Plague35
Bonding/Ground Connection Electrical Resistance Test124
Electronic Equipment Shock Mount158
Preservation ................................................................................. 45, 64, 123, 125, 139, 158, 184
Boric Acid Neutralizing Solution101
Bromothymol Blue Indicating Solution ................................................................................. 100, 103 Litmus Indicating Solution .............................................................................................. 100, 103
Preparation of Solution for Cleaning and Neutralizing Battery Electrolytes100
C Cadmium ................................................................................................ 8, 18, 32, 100, 121, 148, 149
Catastrophic Failures175
Cathode ......................................................................................................................................... 6, 15 Chemical Conversion Material Procedures .......................................................................................... 74, 75
Magnesium Surface Treatment76
Post-Treatment of Conversion Coated Surfaces77
Surface Treatment .................................................................................................................. 9, 74
Treatment of Other Metals77
Cleaning Neutralizing Procedure .................................................................................................... 102, 103 Priority ............................................................................................................................. 181, 182 Surface Preparation ........................................................................................ 59, 78, 96, 149, 171
Versus Calibration124
Coaxial Connectors ........................................................................................ 6, 53, 65, 119, 120, 145 Cockpit Cockpit and Control Boxes ...................................................................................... 105, 106, 136
Cockpit Area Components188
Compounds Electrolyte ................................................................................. 5, 6, 13, 15-17, 44, 100, 125, 169 Electron .............................................................................................................. 5, 6, 87, 169, 172
Electron Conductor6
Galvanic Couple .................................................................................................................... 6, 17 Ion .......................................................................................................................................... 6, 15
Condensed Moisture11
Copper ......................................................................... 7-10, 33-35, 148, 151-158, 163-166, 169, 171 Corrosion Aluminum Surface Treatment .............................................................................................. 32, 75
Effects of Solder Flux37
Effects on Metals32
Effects on Nonmetals36
Factors Influencing6
Index
Fatigue19
Prevention Philosophy21
Preventive Maintenance and Control20
Prone Areas21-26
Electromechanical25
Electronics ........................................................................................... 25, 31, 83, 90, 91, 162 Moisture and Other Fluid Intrusion Sources ...................................................... 21, 24-26, 32 Special Considerations .................................................................................................. 26, 61 Structural ......................................................................................... 24, 74, 77, 108, 111, 146 Resistant Steel ............................................................................................................. 32, 151-156
Theory5
Anode .................................................................................................................. 5, 6, 15, 148 Atom .................................................................................................................................. 5, 6 Cathode ................................................................................................................ 6, 15, 18, 33 Visual Inspection . 28-31, 58, 60, 98, 111, 126, 133, 139, 141, 142, 144-146, 169-171, 187-189, 193, 194 Corrosive Conditions and Elements ................................................................................. 8, 10, 13, 44
Condensed Moisture11
Man-made Environments13
Micro-organism, Insect, and Animal Attack .................................................................. 13, 31, 38 Moisture ............................................................................................................................ 7-11, 13 Other Fluids ......................................................................................................................... 11, 21 Pressure ................................................................................................................................ 11, 13 Temperature ................................................................................................................. 8, 9, 11, 13 Crevice Corrosion ....................................................................................................................... 15, 16 D
Damaged Items194
Discharge Sensitive Equipment172
Desiccants70-72
Direct Failures175
Disassembly Inspection Procedures193
Dissipation of Static Charges176-178
ESD Protection Guidelines176-180
Drying and Preservation of Non-removable Avionics equipment ................................... 190, 191 Drying ..................................................................................................................................... 184, 185
Air Drying62
Coated Equipment88
Preparation62
Preservation Procedures184-186
Solvent Vapor Drying63
with Circulating Air Oven ............................................................................................. 62, 63 with Forced Air Oven ............................................................................................ 63, 98, 184 with Hot Air Blower .................................................................................................... 62, 185 with Vacuum Oven ................................................................................................ 63, 89, 185
Index E Edge Connectors and Mating Plugs ............................................................................... 130, 137, 145 Effects of Corrosion ............................................................................................................ 24, 25-28, 31-44
Dust/Lint Accumulation44
Insect and Animal Attack38
Microbial Attack37
Electrical Bonding and Grounding Straps ........................................................................................ 109, 130
Bonding/Grounding Connections148-158
Bimetallic Junctions148
Hardware ................................................................................................... 148, 151, 153, 156
Connector and Wave guide Caps69
Connectors and Receptacles191
Equipment Shock Mount Bonding Preservation158
Motors and Generators188
Electrolyte ....................................................................................... 5, 6, 13-17, 19, 44, 100, 125, 126
Electron Conductor6
Electrostatic Voltages174
Emergency Cleaning Procedures ......................................................................................... 182-184, 192-195
Aircraft Cleaning Compound184
Alternate Methods ..................................................................................................... 183, 184
Primary Method183
Solvent Method183
Water-Displacing Method .................................................................................. 184, 186-191 Drying and Preservation .................................................................................................. 184, 185
Drying and Preservation Procedures185
Heated Compartment185
Hot Air Blower185
Vacuum Oven Drying185
Vented Drying Oven185
Vented Drying Oven (Bulb Type)185
Preparations181
Emergency Reclamation Team.................................................................................. 181, 192
Production Planning182
Required Tools, Materials, and Equipment182
Reclamation Team Organization181
EMI
Definition159
Precipitation Static162
Protection Maintenance168-171
Shielding Structures162-165
Shielding Design Goals162
Types of Protection162-168
Encapsulates83-98
Drying of Coated Equipment88
Fungus-Proof Coating86-89
Fungus-Proof Varnish86
Methods of Application88
Index
Potting Compounds83-86
Sealant ....................................................................................................................... 84, 85, 90-92
Special Precautions89
Environmental Conditions .......................................................................................................... 10, 21
Environmental Factors10
Equipment Bays ..................................................................................................... 29, 30, 47, 99, 100 Equipment Hinges and Latches .............................................................................................. 108, 109 ESD
Corrosion Inspection and Repair180
Definition172
Direct Failures175
Packaging Practices ......................................................................................................... 177, 180
Protection Guidelines178
Susceptible Equipment175
Workstation Shop Practices ............................................................................................. 177, 180
Evaluation of Corrosion Damage31-44
Exfoliation Corrosion19
External Corrosion Removal and Cleaning ...................................................................... 77, 140, 141
External Mounted Equipment105
F
Factors Influencing Corrosion6
Moisture Intrusion ......................................................................................................... 6, 9-12, 21 Failure Mechanisms ............................................................................................................... 174, 175 ESD-Related Failure of Components ............................................................................... 174, 175 Filters .............................................................................................................................. 145, 162, 168
Fingerprint Removal57
Flush or Dome Antenna Mountings ....................................................................................... 119, 120
Frames, Mounting Racks, and Shock Mounts103
Fretting Corrosion16
Fungus-Proof
Coatings86
Varnish86
Fuselage Shielding162
G Galvanic Corrosion ........................................................................................................... 17, 121, 169 Galvanic Couple ........................................................................................................................... 6, 17
Generation of Static Charges172-174
General Inspection Procedures30
Gold and Gold Plating ........................................................................................... 8, 10, 16, 18, 33-35 H
Hand Cleaning Methods56
Handling ............................................................. 10, 13, 24, 45, 46, 68, 69, 73, 77, 78, 121, 132, 176 Hardware Selection ................................................................................................................ 148, 149
Hazardous Chemicals and Waste Generation49
Hazards of Cleaning54
Index Heated Compartment .............................................................................................................. 185, 186 Hermetically Sealed Avionics Equipment .................................................................................. 9, 187 High Temperature ....................................................................................................................... 13, 92 Hot Air Blower ................................................................................................................. 62, 182, 185
How to Preserve66
Human Body Generated ESD174
Humidity Indicators72
I
In-Place Cleaning190
Inspection Procedures169
General Inspection Procedure30
Inspection Factors28
Water Intrusion Inspection30
Intermittent Failures174
Intergranular Corrosion .............................................................................................................. 19, 34 Internal Cleaning of
Automatic Test Equipment125
General Purpose Test Equipment125-128
Microwave Test Equipment129
Support Equipment ..................................................................................... 45, 107, 124-128, 182 Intrasystem/Intersystem EMI ................................................................................................. 160, 167 Ion ................................................................................................................................................. 5, 15 Iron and Steel ................................................................................................................................ 7, 32 J K L
Latent Failures175
Lighting Systems and Assemblies133
Lightning ................................................................................................................................ 161, 162
Litmus Indicating Solution100
Long Wire and Direction Finder (DF) Sense Antenna Corrosion123
Prevention Procedures123
Lubricants68
M
Maintenance Functions77
Magnesium ........................................................................ 7, 9, 18, 33, 74-76, 83, 108, 151, 153, 155
Magnesium Surface Treatment76
Man-made Environments13
Manufacturing Processes9
Material
Compatibility8
Selection and Use7
Identification Label49
Index Used for Cleaning ........................................................................................................... 46-49, 53
Metallic Equipment Covers and Housings107
Methods of Application88
Methods of Minimizing the Effects of ESD177-180
Meters ............................................................................................................................... 89, 124, 126
Micro-organism, Insect, and Animal Attack13
Military Specifications6
Moisture and Other Fluid Intrusion Sources .......................................................................... 9, 11, 21 Traps and Cavity Areas ........................................................................................................ 7, 109
Mounting Racks and Shock Mounts189
Multi-pin Electrical Connectors, Cleaning and Preservation .......................................... 130, 139-145 N Nonmetallic Deterioration .......................................................................................................... 19, 36 Non-removable Avionics Equipment ..................................................................................... 190, 191 O Operator and Instrument Panels ............................................................................................. 126, 127
Operator/Unit Level Emergency Cleaning Procedures186-192
Antennas189
Cockpit Area Components ............................................................................................... 188, 189
Electrical Connectors and Receptacles191
Electric Motors and Generators188
Hermetically-Sealed Avionics Equipment187
In-Place Cleaning190
Mounting Racks and Shock Mounts189
Non-removable Avionics Equipment190
Removable Avionics Equipment186
Switches and Circuit Breakers188
Terminal Boards, Junction Boxes, Relay Boxes, and Circuit Breaker Panels191
Wiring Harnesses and Cables192
P Packaging
and Storage68-72
Desiccants70-72
Electrical Connector and Wave Guide Caps69
Handling ............................................................................................................................... 68, 69
Humidity Indicators72
Paint Systems ........................................................................................................................... 78, 131 Painting Equipment and Materials ............................................................................................. 78, 79 Pitting ............................................................................................................................. 16, 32, 34, 36
Post-Cleaning Procedure61
Post-Treatment of Conversion Coated Surfaces77
Potting Compounds ............................................................................................................. 83-86, 140
Precipitation Static162
Preservation
How to Preserve66
Index Preservative Materials ................................................................................................................ 66, 67 What Not to Preserve ........................................................................................................... 65, 66
What to Preserve65
When to Preserve ................................................................................................................. 64, 65
Why Preserve64
Pressure Air .................................................................................................................................. 13, 51, 72
Contact12
Prime Sources of Static Charge172-174
Production Planning182
Program Requirements20
Proper Package Practices .......................................................................................................... 69, 180
Protective Coatings77-83
Application of Coatings80
Application of Primer80
Application of Topcoat83
Printed Circuit Boards (PCB) .................................... 7, 8, 16, 50, 51, 53, 62, 68, 84, 93-98, 130, 145
Purple Plague35
Q R
Radar Antenna Associated Hardware121
Radar Dish Antenna Corrosion Prevention Procedures121
Recognizing Avionics Corrosion31
Aluminum32
Black Plague35
Cadmium35
Corrosion Effects of Solder Flux37
Corrosion Effects on Nonmetals36
Corrosion Resistant Steel32
Copper33
Effects of Insect and Animal Attack38
Effects of Microbial Attack37
Gold and Gold Plating35
Iron and Steel32
Magnesium33
Nickel35
Purple Plague35
Red Plague35
Silver35
Tin35
Recommended Practices for ESD Sensitive Equipment180
Basic ESD Precautions178-180
Packaging Practices178-180
Sensitive Device Handling Practices178-180
Testing and/or Repair Practices178-180
Red Plague35
Relay and Circuit Breakers135
Removal and Cleaning of Identification and Modification Plates186
Index Removal Priority .................................................................................................................... 181, 186 Repair of
Avionics Equipment Housings, Mounting Racks, and Storage Hardware99-111
Bilge Areas99
Cockpit and Control Boxes105
Electrical Bonding and Grounding Straps109
Engine Compartments100
Equipment Bays99
Equipment Covers, Hinges, and Latches ................................................................... 107, 108
External Mounted Equipment105
Frames, Mounting Racks, and Shock Mounts103
Internal Metal Surfaces146
Moisture Traps and Cavity Areas109
Terminal Boards, Junction Boxes, Relay Boxes, and Circuit Breaker Panels107
Avionics Systems, Equipment, and Components111
Aluminum Electrolytic Capacitors138
Antenna Bonding/Ground Connection124
Electrical Resistance Test124
Antenna Connectors121
Antenna Mounting Area Preparation Procedures .............................................. 111, 116, 119
Antenna Systems111
ATE Cabinets, Doors, and Panels125
Battery Compartments ............................................................................................... 100, 126
Cleaning Versus Calibration124
Coaxial Connectors145
Corrosion Visual Inspection .............................................................................. 111, 169, 170
Edge Connectors and Mating Plugs137
External Corrosion Removal and Cleaning ............................................................... 140, 141
Filters145
Flush or Dome Antenna Mounting119
Handling, Storage, and Packaging132
Internal Cleaning of General Purpose Test Equipment128
Internal Cleaning of Microwave Test Equipment129
Internal Corrosion Removal and Cleaning142
Lighting Systems and Assemblies133
Long Wire/Direction Finder Sense Antenna123
Meters126
Multi-pin Electrical Connectors, Cleaning, and Preservation ................................... 130, 139
Operator and Instrument Panels126
Painting Systems131
Printed Circuit Boards ............................................................................................... 130, 145
Battery Compartments, Boxes, and Adjacent Areas100
Radar Antenna Associated Hardware121
Relays and Circuit Breakers ............................................................................................. 130, 135 Sealing Connector Back shells ......................................................................................... 143, 144
Sensitive Internal Metal Surfaces146
Special Cleaning Procedures130
Support Equipment/General Purpose Test ....................................................................... 127, 128 Equipment Covers and Housings ..................................................................................... 107, 125 Switches ........................................................................................... 105, 126, 127, 130, 136, 188
Temporary Dish Protection121