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MAINTENANCE MANUAL
ELECTRICAL SYSTEM STANDARD PRACTICES — MAINTENANCE PRACTICES
1. Electrical Bonding — Standard Practices
A. General
A bond is an electrically conductive joint. Bonds are assembled either directly, using fasteners and /
or clamps, or indirectly by using bonding straps or bonding wire.
Bond surfaces are small areas on aircraft structures and / or electrical bonding hardware that provide
a path for dissipation of electrical energy.
A bonding strap is any conductor that is used for providing low impedance electrical bonding between
any two points. A bonding strap is also called a bonding jumper.
Electrical bonding and grounding of Gulfstream aircraft structures are used for ensuring the following:
• Aircraft structures, equipment, and personnel are protected from hazards of lightning
discharges
• Homogeneous and stable paths for all electrical currents are established
• Radio Frequency (RF) potentials on enclosures, antennas and other aircraft structures are
minimized
• Personnel are protected from shock hazards that may develop from accidental power grounds
• Static charge accumulation on aircraft structures is prevented
B. Preparation
SPECIAL TOOLS AND TEST EQUIPMENT
Digital Low Resistance Ohmmeter (DLRO) ........................................................ Biddle or equivalent
CONSUMABLES
Alodine 600 ....................................................................................................................... MIL-C-5541
Applicator ............................................................................ Scotch Brite pad, sponge, brush or cloth
Methyl Prophyl Ketone (MPK) ............................................................................................. GAS115K
(1) Aircraft Preparation
(a) Prepare aircraft for safe ground maintenance.
(b) When making any electrical bonding or grounding connections to aircraft, observe the
following general precautions:
1 Bond or ground parts to primary aircraft structure where practicable.
2 Make bonding or grounding connections so aircraft structure is not in any way
weakened.
3 Bond parts individually wherever possible.
4 Make bonding or grounding connections to clean, smooth surfaces.
5 Install bonding or grounding connections so vibration, expansion, contraction or
relative movement will not break or loosen connection under normal service use.
6 Locate bonding and grounding connections in protected areas whenever possible.
Locate near access panels, inspection doors or other accessible areas to permit
easy inspection and replacement.
7 Do not compression fasten bonding or grounding connections to any nonmetallic
material.
8 Inspect grounding and bonding straps periodically to insure they are free of
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corrosion, fraying or cut more than 25 percent of original strap.
9 No more than four ground wires will be connected to a common ground stud.
10 Ground modules may be used for multiple grounds.
11 Bonding straps should not exceed a length to width ratio of 5:1 and should be kept
short as possible.
(2) Surface Preparation
NOTE: Surface preparation for electrical bonding requires complete removal of anodic film,
grease, oil, paint, lacquer, metal finishes and other resistive coatings from area slightly
larger than bonding surface. A clean, smooth, properly contoured electrical surface
should be obtained while removing minimal amount of metal.
(a) Clean bonding and grounding surfaces thoroughly with a nonmetallic abrasive pad, fine or
medium grade.
NOTE: Do not use abrasives such as carbon steel or stainless steel rotary brushes,
emery cloth or iron oxide sandpaper as they leave particles imbedded in surface
or scattered in area causing corrosive action.
(b) Wipe clean with dry cloth.
(3) Comply with the following bonding / grounding procedure as applicable:
• Aluminum Surfaces - See Step 1.C.(1)
• Steel Surfaces - See Step 1.C.(2)
• Ground Studs - See Step 1.C.(3)
• Antenna Bonding or Grounding - See Step 1.C.(4)
• Electrical Bonding Resistance Limitations - See Step 1.C.(5)
C. Procedure
(1) Aluminum Surfaces
WARNING: ALWAYS WEAR ADEQUATE PERSONAL PROTECTIVE EQUIPMENT WHEN
USING SOLVENTS AND CLEANING FLUIDS. AVOID BREATHING FUMES.
KEEP AWAY FROM SPARK PRODUCING DEVICES AND OPEN FLAME.
NOTE: A stainless steel rotary wire bonding brush with pilot may be used to clean small
areas. See Figure 201.
(a) Remove any nonsoluble protective finishes or corrosion from a diameter of area to be
cleaned of at least 1.5 times diameter of hole with fine sandpaper.
(b) Clean exposed bonding surface thoroughly with clean cheesecloth. Cheesecloth shall be
either dry or wet with Methyl Prophyl Ketone (MPK).
NOTE: Do not touch bonding surface with bare hands. Body oils or acids will prevent
adhesion of alodine film or cause corrosion.
(c) Shake alodine solution vigorously just prior to application, then apply to bonding surface.
NOTE: Alodine solution should have an amber color. If solution is coffee colored, it has
become contaminated.
(d) Keep treated area wet with alodine for approximately 3 - 5 minutes until a yellow color
develops.
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NOTE: Should alodine not change color, it is an indication that surface was not properly
cleaned.
(e) After alodine has changed color, rinse area with clean de-ionized water and gently wipe
dry with a clean cloth. Touch up any areas where alodine does not cover bonding surface.
NOTE: Care should be used not to damage alodine coating, since it is still soft when
bonding. Once dried, alodine must be softened before it can be effectively used
in bonding.
Bonding surfaces must be assembled within 1 hour of alodine treatment. If more
than an hour has passed, soften alodine by applying wet alodine to dried
surface.
(f) Install component being electrically bonded.
(g) If assembly was originally protected by primer, prime surface area and reapply original
finish as required.
NOTE: Bonding area must be refinished within 24 hours of electrical bonding to
preserve integrity of bond. If bond involves a structural component, it must be
fillet sealed to prevent moisture from entering and deteriorating electrical
bonding surfaces.
(2) Steel Surfaces
WARNING: ALWAYS WEAR ADEQUATE PERSONAL PROTECTIVE EQUIPMENT WHEN
USING SOLVENTS AND CLEANING FLUIDS. AVOID BREATHING FUMES.
KEEP AWAY FROM SPARK PRODUCING DEVICES AND OPEN FLAME.
(a) Remove all grease and oil from electrical bonding surface using cleaner and dry cloth.
(b) Remove all paint or lacquer from electrical bonding surface using clean cloth saturated
with MPK.
NOTE: Use care not to remove zinc or cadmium plating from steel surfaces.
(c) Allow surface to dry thoroughly.
(d) Install component being bonded electrically.
(e) If assembly was originally protected by primer, prime surface area and reapply original
finish as required.
NOTE: Bonding area must be refinished within 24 hours of electrical bonding to
preserve integrity of bond. If bond involves a structural component, it must be
fillet sealed to prevent moisture from entering and deteriorating electrical
bonding surfaces.
(3) Ground Studs
WARNING: ALWAYS WEAR ADEQUATE PERSONAL PROTECTIVE EQUIPMENT WHEN
USING SOLVENTS AND CLEANING FLUIDS. AVOID BREATHING FUMES.
KEEP AWAY FROM SPARK PRODUCING DEVICES AND OPEN FLAME.
(a) Remove any nonsoluble protective finishes or corrosion from area to be cleaned at least
1.5 times the diameter of hole with fine sandpaper.
A stainless steel rotary wire bonding brush with pilot may be used to clean small areas.
(b) Clean exposed bonding surface thoroughly with clean cheesecloth. Cheesecloth shall be
either dry or wet with MPK.
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NOTE: Do not touch bonding surface with bare hands. Body oils or acids will prevent
adhesion of alodine film or cause corrosion.
(c) Install ground stud using appropriate hardware. See Table 201 and Figure 202.
(d) If assembly was originally protected by primer, prime surface area and reapply original
finish.
NOTE: Bonding area must be refinished within 24 hours of electrical bonding to
preserve integrity of bond. If bond involves a structural component, it must be
fillet sealed to prevent moisture from entering and deteriorating electrical
bonding surfaces.
(e) Using low resistance ohmmeter, perform bond resistance test. Measurement shall not
exceed 0.0025 ohms. See Figure 203.
(4) Antenna Bonding or Grounding
(a) Remove screws securing antenna to fuselage.
(b) Lift antenna up and disconnect electrical connector on antenna. See Figure 204.
(c) Prepare antenna surface. See Step 1.C.(1) Aluminum Surfaces.
(d) Using low resistance ohmmeter, perform bond resistance test. Measurement shall not
exceed 0.0025 ohms. See Figure 203.
(5) Electrical Bonding Resistance Limitations
COCKPIT LIMIT
(Ohms)
Pilot CB Panel 0.10
Copilot CB Panel 0.10
LIMIT
BAGGAGE / TAIL COMPARTMENT
(Ohms)
Aux Power Junction and Relay Panel 0.0025
Tail Junction and Relay Box 0.0025
LIGHTS LIMIT
(Ohms)
Strobe Tail Bottom Fuselage 0.0025
Strobe Tail Top Fuselage 0.0025
Anti-collision Lights 0.0025
L / R Wing Strobe Light 0.0025
Pulselite Control 0.0025
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EXTERNAL EQUIPMENT(1) LIMIT
(Ohms)
TAT Probes 0.10
Static Port 0.10
Static Probes 0.10
Drain Masts 0.10
Weather Radar RTA 0.0025
Static Wick Base 50.0
(1)
All external equipment bond tests should be conducted from inside
fuselage to accessible equipment only.
STRUCTURAL LIMIT
(Ohms)
Right Engine 0.10
Left Engine 0.10
Main Door 0.0025
Baggage Door 0.0025
Horizontal Stabilizer bonded to tail 0.0025
L / R Elevators bonded to horizontal 0.01
stabilizer
L / R Elevator Tabs bonded to 0.01
horizontal stabilizer
Rudder bonded to tail 0.0025
L / R Aileron bonded to wing 0.0025
L / R Aileron Actuators bonded to wing 0.0025
L / R Flaps bonded to wing 0.0025
L / R Spoilers bonded to wing 0.0025
L / R Flight Spoiler RVDT’s bonded to 0.0025
wing
L / R Ground Spoiler RVDT’s bonded to 0.0025
wing
L / R Spoiler Position Switches bonded 0.0025
to wing
L / R Winglets bonded to wing 0.0025
L / R Crane Beams bonded to airframe 0.0025
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STRUCTURAL LIMIT
(Ohms)
Pressure Floorboards bonded to 0.0025
airframe
L / R Nose Wheel Doors bonded to 0.0025
airframe
Nose Wheel Fairing bonded to airframe 0.0025
L / R Leading Edge bonded to wing 0.0025
L / R Wing Access Covers bonded to 0.0025
wing
Windshield Frame (left front) bonded to 0.0025
airframe
Windshield Frame (right front) bonded 0.0025
to airframe
Windshield Frame (center) bonded to 0.0025
airframe
L / R Pylons bonded to airframe 0.0025
Nose Radome bonded to airframe 0.0025
Nose Radome Lightning Diverters 0.010
bonded to airframe
ENVIRONMENTAL CONTROL LIMIT
SYSTEMS(1) (Ohms)
Outflow Valve 10.0
Air Condition Turbines 1.0
ECS Ducting 1.0
ECS Valve 10.0
ECS Heat Exchangers 1.0
(1)
When measuring bonding limits on ECS ducting and ECS valves,
measurements will be taken from each section of duct or valve to
airframe.
LIMIT
POWERPLANT SYSTEMS
(Ohms)
Crane Beams 0.0025
Thrust Reversers 0.0025
Engine Fuel Lines 0.01
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LIMIT
POWERPLANT SYSTEMS
(Ohms)
APU Fuel Feed Line 0.01
Fuel Shut Off Valve 0.01
Cross Feed Shut Off Valve 0.01
Main Fuel Boost Pump 0.01
Alternate Fuel Boost Pump 0.01
Intertank Shut Off Valve 0.01
Upper Cowl 0.03
Lower Cowl 0.03
Nose Cowl 0.03
LIMIT
MISCELLANEOUS
(Ohms)
Nose Wheel Well Switch Panel 0.0025
Aux Hydraulic Pump 0.1000
AOA Transmitters 0.0025
Flap Position Transmitter 0.0025
VLF Conduit 0.0025
Flux Valve Bracket 0.0025
SATCOM / DBS LIMIT
RADOME LIGHTNING DIVERTERS (Ohms)
Nose / Forward Radome Lightning 0.010
Diverter Termination Screw
Left Mid Radome Lightning Diverter 0.010
Termination Screws
Right Mid Radome Lightning Diverter 0.010
Termination Screws
Saddle Radome Lightning Diverter 0.010
Termination Screw
NOTE: Airframe test points for nose / forward, mid and saddle radome lightning diverter
disbond checks will be horizontal stabilizer rub blocks. See Figures 205 and 206.
(6) Inspect for presence of foreign objects.
(7) Record all maintenance actions in accordance with current Federal Aviation Regulations.
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Table 201: Hardware for Stud Bonding or Grounding to Flat Surface
STRUCTURE SCREW PLAIN NUT WASHER WASHER WASHER LOCK LOCK
OR BOLT A B C AND D WASHER WASHER
LOCKNUT E F
Aluminum Terminal and Jumper
Aluminum Cadmium Tin Plated Aluminum Aluminum Cadmium Cadmium Cadmium
Alloys Plated Brass Alloy Alloy Plated Plated Plated
Steel Steel or Steel Steel
Aluminum
Magnesium Cadmium Cadmium Magnesium Magnesium Cadmium Cadmium Cadmium
Alloys Plated Plated Alloy Alloy Plated Plated Plated
Steel Steel Steel or Steel Steel
Aluminum
Cadmium Cadmium Cadmium None None Cadmium Cadmium Cadmium
Plated Steel Plated Plated Plated Plated Plated
Steel Steel Steel or Steel Steel
Aluminum
Corrosion Corrosion Cadmium None None Cadmium Corrosion Cadmium
Resistant Steel Resistant Plated Plated Resistant Plated
Steel Steel Steel or Steel Steel
Aluminum
Tinned Copper Terminal and Jumper(1)
Aluminum Cadmium Cadmium Aluminum Aluminum Cadmium Corrosion Cadmium
Alloys Plated Plated Alloy Alloy Plated Resistant Plated
Steel Steel Steel Steel Steel
Magnesium Alloys
Cadmium Cadmium Cadmium None None Cadmium Cadmium Cadmium
Plated Steel Plated Plated Plated Plated Plated
Steel Steel Steel Steel Steel
Corrosion Corrosion Corrosion None None Cadmium Corrosion Corrosion
Resistant Steel Resistant Resistant Plated Resistant Resistant
Steel Steel Steel Steel Steel
(1)
Avoid connecting copper to magnesium.
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Use of Stainless Steel Rotary Wire Brush
Figure 201
Ground Stud Arrangement Bonding or Grounding to Flat Surface
Figure 202
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Proper Meter Setup / Connection
Figure 203
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Cleaning of Bonding Surfaces on Antenna Mounting Areas
Figure 204
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Lightning Diverter Termination Screw
Figure 205
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Horizontal Stabilizer Rub Block Location
Figure 206
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