Measurement of the Surface Electrical Resistance of External Composite Panels (without Non-Conductive Finish Paint) with Probes

TASK 20-28-00-720-011-A-02
Measurement of the Surface Electrical Resistance of External Composite Panels (without Non-Conductive Finish Paint) with Probes

1. Reason for the Job
You must measure the surface electrical resistance if you installed the panels after some modifications or repairs.

NOTE: The measurement of the surface electrical resistance is not necessary if the panels are installed subsequently to their removal without modifications or repairs.

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	MEGOHMETER MULTIRANGE
No specific	1	OHMMETER MULTIRANGE
No specific	1	PROBE - DIN 65181

B. Referenced Information

REFERENCE	DESIGNATION
TASK 20-28-00-720-011-A	Measurement of the Surface Electrical Resistance of External Composite Panels with a Resistivity Test Set
TASK 20-28-00-869-002-A	Table of the Maximum Permitted Resistance-Values
Measurement Points on Different Panels

3. Job Set-up
Subtask 20-28-00-869-088-A

A. General
(1) The recommended procedure for the measurement of the surface electrical resistance of an external composite panels (with or without non-conductive finish paint on the antistatic paint) uses a resistivity test set (Ref. AMM TASK 20-28-00-720-011).
(2) This procedure gives an alternative procedure for the measurement of the surface electrical resistance of an external composite panel. This procedure is applicable only if there is no non-conductive finish paint on the antistatic paint.

4. Procedure
Subtask 20-28-00-869-089-A

A. Measurement of the Surface Electrical Resistance
(1) Equipment
(a) For fairings (but not and antenna fairing or a radome), use an OHMMETER MULTIRANGE, with the applicable leads and prods, diameter 4 mm (0.16 in.).

Set the ohmmeter range to a value that is higher than the maximum permitted value of the assembly that you will measure (Ref. AMM TASK 20-28-00-869-002).
Set the tension to 500 VDC.

(b) For antenna fairing or a radome, use a MEGOHMETER MULTIRANGE, with the applicable leads and prods, diameter 4 mm (0.16 in.).

Set the megohmmeter range to a value that is higher than the maximum permitted value of the assembly that you will measure (Ref. AMM TASK 20-28-00-869-002).
Set the tension to 500 VDC.

NOTE: You can use 2 rounded-point prods, diameter 4 mm (0.16 in.) as an alternative to the DIN 65181 probe.

(2) Connect the probe to the ohmmeter/megohmmeter.
(3) Apply the prod on the surface covered with the antistatic paint.

the distance between the edge of the surface and the probe must be at least 50 mm (1.97 in.) (Typical 100 mm (3.94 in.)).

NOTE: The pressure applied on the probe must be sufficient to prevent the oscillations of the ohmmeter/megohmmeter display.

(4) Measure the square resistance value.

NOTE: For probes that have electrodes 100 mm (3.94 in.) apart, you must multiply the measured value by 0.5 to get the Square Resistance value.

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

NOTE: Do the steps (2) to (5) again several times at different areas of the surface.

Measurement Points on Different Panels

(6) Remove the test equipment.

5. Close-up
Subtask 20-28-00-942-114-A

A. Make sure that the work area is clean and clear of tools and other items.

[Rev.10 from 2021] 2026.03.31 23:00:17 UTC