Different Total Pressure on the ADIRU 1 and the ADIRU 2

TASK 34-11-00-810-840-A
Different Total Pressure on the ADIRU 1 and the ADIRU 2

1. Possible Causes

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

REFERENCE	QTY	DESIGNATION
No specific	AR	ARINC READER

B. Referenced Information

REFERENCE	DESIGNATION
AMM 30-31-00-720-001	Functional Check of the Insulation Resistance of the Pitot Probe Heater
AMM 34-10-00-170-001	Flushing of the Principal Total Pressure Lines
AMM 34-10-00-860-002	ADIRS Start Procedure
AMM 34-11-15-000-001	Removal of the Pitot Probe
AMM 34-11-15-400-001	Installation of the Pitot Probe
AMM 34-11-17-000-001	Removal of the Air Data Module
AMM 34-11-17-400-001	Installation of the Air Data Module
AMM 34-13-00-790-002	Leak Test of the Principal Static and Total Air Data System
ASM 341301

3. Fault Confirmation
Subtask 34-11-00-710-056-A

A. Test
Not applicable, you cannot confirm this fault on the ground.

4. Fault Isolation
Subtask 34-11-00-810-095-B

A. If the POST FLIGHT REPORT gives the maintenance message ADM1 (19FP1)/ ADM2 (19FP2):

(1) If the pitot probe 1 (9DA1) or the pitot probe 2 (9DA2) is damaged:

(2) If the pitot probes are not damaged:

do the ADIRS start procedure AMM 34-10-00-860-002
connect the ARINC READER to the test connector 198VC on the panel 188VU and to the test connector 199VC on the panel 187VU ASM 341301

compare the total pressure read on these labels:

ADIRU 1 199VC ! 19FP1 LABEL 242

pins GG, HH !

ADIRU 2 198VC ! 19FP2 LABEL 242

pins GG, HH !

ADIRU 3 199VC ! 19FP3 LABEL 242

pins y, z !

(a) If the value of the total pressure (ADM 1 or ADM 2) is different:

replace the defective total pressure ADM AMM 34-11-17-000-001 and AMM 34-11-17-400-001.

(b) If the values are the same:

do the flushing of the total pressure line of the air data module (ADM 1 and ADM 2) AMM 34-10-00-170-001
do the leak test of the main air data system (CAPT and F/O) AMM 34-13-00-790-002.

(3) Do the functional test of the pitot-probe-heater insulation resistance AMM 30-31-00-720-001.

if the resistance value is not in the correct range, replace the defective pitot probe (9DA1 or 9DA2) AMM 34-11-15-000-001 or AMM 34-11-15-400-001.

Subtask 34-11-00-810-096-A

B. After the subsequent flight, if the fault continues:

Subtask 34-11-00-810-097-A

C. After the subsequent flight, if the fault continues:

[Rev.8 from Aug 2018] 2026.04.04 04:32:15 UTC