System Maintenance Manual

G1000/GFC700 System Maintenance Manual – C90A/C90GT/C90GTi King Air Page 4-17
190-00682-01 Revision G
4.5.4 Phase 4 Electrical Bonding Procedure
1. Connect the positive lead of the power supply to the engine compartment grounding bracket (battery
negative connection to the airframe). Connect/touch the positive lead of the voltmeter to the same
point.
NOTE
Ensure that the voltmeter and power supply probes do not touch, so as not to induce
contact resistance.
2. Touch negative lead of power supply to each of the test points listed while performing Step 3. At
each point, configure the power supply to produce 1 amp before measuring voltage. (Use an ammeter
to ensure current is within 1 amp ±100 milli-amp at each point).
3. Set the voltmeter to measure milli-volts and null the reading. Measure the voltage from the engine
grounding bracket (step 1) to each of the following points and record the voltage. (Perform Step 2 at
each point to ensure that 1 amp ±100 milli-amp is present before measuring)
Nose Section
• GWX 68 body: __________ milli-volts
Nose Avionics Compartment
• GIA 1 top: __________ milli-volts
• GIA 2 top: __________ milli-volts
• GTX 33 #1 top: __________ milli-volts
• GTX 33 #2 top: __________ milli-volts
• GRS 77 #1 metal base: __________ milli-volts
• GRS 77 #2 metal base: __________ milli-volts
• Standby battery: __________ milli-volts (may be installed in rear fuselage)
Rear Fuselage and Empennage
• GMU 44 #1 metal base: __________ milli-volts
• GMU 44 #2 metal base: __________ milli-volts
• GSA 80 (Pitch) Servo body: __________ milli-volts
• GSA 81 (Pitch Trim) Servo body: __________ milli-volts
• GSA 80 (Yaw) Servo body: __________ milli-volts
TIP: If 1 amp reference current cannot be maintained, note the difference between the attainable current
and 1 amp reference current. Calculate the percentage difference and apply this to the voltage reading to
obtain the equivalent resistance. Example: If the measured current is 1.2 amps, (20% high from the target
1 amp current), then the allowable voltage measurement would be 20% high, 2.5 milli-volts would now
be 3.0 milli-volts.