Adjustment of the Altitude Pressure Switch

TASK 38-31-00-820-003-A
Adjustment of the Altitude Pressure Switch

FIN: 43MG ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 4M (13 FT)
No specific	1	TEST UNIT-STATIC PITOT
98D38308234001	1	ADAPTER - ALTITUDE PRESSURE SWITCH

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
312AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
TASK 32-69-00-860-001-A	Simulation of Flight (With Aircraft on Ground)
TASK 38-31-00-710-002-A	Operational Test of the Vacuum Toilet System

3. Job Set-up
Subtask 38-31-00-861-067-A ** ON A/C NOT FOR ALL

A. Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).

Subtask 38-31-00-010-080-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Put the ACCESS PLATFORM 4M (13 FT) in position.
(2) Open the access door 312AR.

Subtask 38-31-00-860-057-A ** ON A/C NOT FOR ALL

C. Preparation for Adjustment
(1) Remove the electrical connector from the altitude pressure switch 43MG.
(2) Install the 98D38308234001 ADAPTER - ALTITUDE PRESSURE SWITCH on the altitude pressure switch 43MG.
(3) Connect the TEST UNIT-STATIC PITOT to the altitude pressure switch-adapter.

4. Procedure
Subtask 38-31-00-710-063-A ** ON A/C NOT FOR ALL

A. Do this Test

ACTION	RESULT
1.On the pitot tester: set the altitude to 4877 +213 m or -213 m (16000.95 +698.83 ft. or -698.83 ft.).	At the altitude pressure switch 43MG: do a check for continuity between the pins A and B. the pins A and B should monitor switch contact close.
2.On the pitot tester: decrease the altitude to 3658 m (12001.53 ft.).	At the altitude pressure switch 43MG: do a check for continuity between the pins A and C. the pins A and C should monitor switch contact close. NOTE: The switch contacts do not have to close at exactly 3658 m (12000 ft), but can also close at a higher altitude.

Subtask 38-31-00-820-051-A ** ON A/C NOT FOR ALL

B. Adjust the Altitude Pressure Switch 43MG
(1) Remove the test adapter from the altitude pressure switch.
(2) Use a 3/32 inch Allen wrench and adjust the screw in the center of the base of the switch.

NOTE: You must turn the screw to the left to increase the altitude pressure threshold of the switch. Turn the screw to the rihgt to decrease the altitude pressure threshold of the switch.

NOTE: A 1/2 turn of the screw will give approximately 0.05 bar (0.77 psi) to 0.07 (0.96 psi) altitude pressure.

(3) Install the test adapter and do the test in para 4. A. again.
(4) If the test is not satisfactry, do the adjustment in para 4. B. again until the altitude is correct.

Subtask 38-31-00-710-064-A ** ON A/C NOT FOR ALL

C. Test
(1) Make sure that all the electrical connections are clean and in the correct condition.
(2) Connect the electrical connector to the altitude pressure switch.
(3) Simulate the LGCIU 2 in the flight configuration on the CFDS (Ref. AMM TASK 32-69-00-860-001).
(4) Do the operational test of the vacuum toilet system (Ref. AMM TASK 38-31-00-710-002).

5. Close-up
Subtask 38-31-00-410-078-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(2) Make sure that the work area is clean and clear of tools and other items.
(3) Close the access door 312AR.
(4) Remove the access platform(s).

Subtask 38-31-00-862-066-A ** ON A/C NOT FOR ALL

B. De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).

[Rev.10 from 2021] 2026.04.01 01:19:37 UTC