Check of the Electrical Bonding of the Different Components (but not Fluid Systems and Components Installed on Composite Materials) with a Millivoltmeter

TASK 20-28-00-720-001-A
Check of the Electrical Bonding of the Different Components (but not Fluid Systems and Components Installed on Composite Materials) with a Millivoltmeter

1. Reason for the Job
This test is to measure the electrical resistance with a Variable Power Supply Unit (PSU) and a millivoltmeter.
This procedure is not applicable to components installed in fuel tanks or surge tanks (explosive atmosphere) or at the boundary of an explosive atmosphere.
Refer to AMM task 20-28-00-720-006-A for the procedure related to electrical resistance measurements of the fluid systems.
2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TASK 20-28-00-869-002-A	Table of the Maximum Permitted Resistance-Values

3. Job Set-up
Subtask 20-28-00-869-053-A

A. Equipment
(1) Variable Power Supply Unit (PSU), continuous output test current of 10 amperes (24 volts nominal).

NOTE: The ratings of the wires that connect the PSU to the components on which you do the test must be :

at least 25% higher than the maximum current used in the test
for the low-current test, the wire rating = 13 amperes.

(2) Ammeter - FSD 10 amperes.
(3) Millivoltmeter - multirange

RANGE	1	2	3	4	5
FSD	2mV	20mV	200mV	2V	20V

4. Procedure
Subtask 20-28-00-420-078-A

A. Measurement of the Electrical Resistance

CAUTION: MAKE SURE THAT YOU DO NOT CAUSE DAMAGE TO THE EQUIPMENT OR THE STRUCTURE WHEN YOU USE SHARP-POINT PRODS.

CAUTION: MAKE SURE THAT THE TEST EQUIPMENT IS CORRECTLY INSTALLED BEFORE YOU MEASURE THE BONDING VALUES.

(1) Connect the PSU.

NOTE: Make all the connections as near as possible to the bonding or grounding point.

NOTE: Make sure that the connections are clean and have no grease.

(2) Adjust the PSU to get a test current of 10 amperes on the ammeter.

NOTE: Start with the PSU at its low setting.

(3) Put one prod of the millivoltmeter on the structure adjacent to the bonding point and the other prod on the component (put them adjacent to the bonding points and make sure that there is a good contact).

NOTE: Start the test with the millivoltmeter in the 20V range. Go down in sequence through the ranges to get the highest movement of the needle on the scale.

(4) Measure and write the values.
(5) Remove the prods, de-energize the power supply and disconnect the test circuit.
(6) Calculate the resistance in milliohms:

divide the voltage in millivolts by the current in amperes.

(7) Make sure that the measured values are not higher than the maximum permitted values. (Ref. AMM TASK 20-28-00-869-002)

5. Close-up
Subtask 20-28-00-942-090-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.

[Rev.10 from 2021] 2026.03.31 23:00:06 UTC