Failure of the Pitot Probe (PHC 3)

TASK 30-31-00-810-824-A
Failure of the Pitot Probe (PHC 3)

1. Possible Causes

PROBE-PITOT, 3 [9DA3]
PHC-3 [6DA3]
wiring from the PHC 3 (6DA3) to the pitot probe 3 (9DA3)
wiring
ADIRU-3 [1FP3]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 30-31-00-710-001	Operational Test of the Probe Ice Protection
ASM 303103
AMM 30-31-34-000-002	Removal of the Probe Heat Computer (PHC)
AMM 30-31-34-400-002	Installation of the Probe Heat Computer (PHC)
AMM 34-11-15-000-001	Removal of the Pitot Probe
AMM 34-11-15-400-001	Installation of the Pitot Probe
AMM 34-12-34-000-001	Removal of the ADIRU
AMM 34-12-34-400-001	Installation of the ADIRU
ASM 341302

3. Fault Confirmation
Subtask 30-31-00-710-096-A

A. Test
(1) Do the operational test of the probe ice protection AMM 30-31-00-710-001.

4. Fault Isolation
Subtask 30-31-00-810-073-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message PITOT PROBE 9DA3:

Disconnect the connector from the pitot probe 3 (9DA3) and do a check of the resistance between pin A/B and pin A/C.

(1) If the resistance is more than 35,7 ohms (open circuit) or less than 32,3 ohms (short circuit) at a temperature of 20 deg.C (68 deg.F):
(a) Replace the PROBE-PITOT, 3 [9DA3] , AMM 34-11-15-000-001 and AMM 34-11-15-400-001.
(2) If the resistance is between 32,3 ohms and 35,7 ohms at a temperature of 20 deg.C (68 deg.F):
(a) Replace the PHC-3 [6DA3] , AMM 30-31-34-000-002 and AMM 30-31-34-400-002.
(b) If the fault continues:

Do a check and repair the wiring from the PHC 3 (6DA3) to the pitot probe 3 (9DA3) pin A/H to pin A/B ASM 303103.

(3) If the fault continues:
(a) Disconnect connector A from PHC 3 and remove ADIRU 3 AMM 34-12-34-000-001.
(b) Do a check of the probe signal wiring ASM 341302 between PHC 3 pin A/<B and ADIRU 3 pin AA/4J.
1 If there is no continuity:

Repair the wiring and
Install ADIRU 3 AMM 34-12-34-400-001.

2 If there is continuity:

Replace ADIRU-3 [1FP3] AMM 34-12-34-400-001.

Subtask 30-31-00-810-073-D ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message PITOT PROBE 9DA3:

disconnect the connector from the pitot probe 3 (9DA3) and do a check of the resistance between pin A/B and pin A/C.

(1) If the resistance is more than 34 ohms (open circuit) or less than 24 ohms (short circuit) at a temperature of 20 deg.C (68 deg.F):
(a) Replace the PROBE-PITOT, 3 [9DA3] , AMM 34-11-15-000-001 and AMM 34-11-15-400-001.
(2) If the resistance is between 24 ohms and 34 ohms at a temperature of 20 deg.C (68 deg.F):
(a) Replace the PHC-3 [6DA3] , AMM 30-31-34-000-002 and AMM 30-31-34-400-002.
(b) If the fault continues:

Do a check and repair the wiring from the PHC 3 (6DA3) to the pitot probe 3 (9DA3) pin A/H to pin A/B ASM 303103.

Repair the wiring and
Install ADIRU 3 AMM 34-12-34-400-001.

2 If there is continuity:

Replace ADIRU-3 [1FP3] AMM 34-12-34-400-001.

Subtask 30-31-00-710-097-A

B. Do the operational test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:29:36 UTC