Loss of the Power Supply for the Pitot Probe (PHC 2)

TASK 30-31-00-810-815-A
Loss of the Power Supply for the Pitot Probe (PHC 2)

1. Possible Causes

PHC-2 [6DA2]
wiring between the PHC 2 pin A/S and the ground terminal
wiring between the PHC 2 pin A/A and the circuit breaker (3DA2)
wiring from the PHC 2 (6DA2) pin A/H to the pitot probe 2 (9DA2) pin A/B
C/B-ANTI ICE/PROBES/2/PITOT [3DA2]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 24-00-00-810-803-A	Circuit Breaker Tripped and/or C/B TRIPPED Warning
AMM 30-31-00-710-001	Operational Test of the Probe Ice Protection
ASM 303101
ASM 303102
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

3. Fault Confirmation
Subtask 30-31-00-710-078-A

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

4. Fault Isolation
Subtask 30-31-00-865-053-A

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	ANTI ICE/PROBES/2/PITOT	3DA2	Y14

Subtask 30-31-00-810-064-B ** ON A/C NOT FOR ALL

B. If the test gives the maintenance message CHECK PITOT PHC 2 SUPPLY:

Do a check of the status of the circuit breaker (3DA2).

(1) If the circuit breaker is closed:

Do a check for 115VAC at pin A/A of the PHC 2 (6DA2).

(a) If there is no 115VAC:

Replace the PHC-2 [6DA2] AMM 30-31-34-000-002 and AMM 30-31-34-400-002.

(b) If there is 115VAC:

Do a check for a ground signal at pin A/S of the PHC 2 (6DA2).

1 If there is no ground signal:

Repair the wiring between the PHC 2 pin A/S and the ground terminal ASM 303102.

2 If there is a ground signal:

Do a check of the wiring between the PHC 2 pin A/A and the circuit breaker (3DA2).

a If there is no continuity:

Repair the above wiring.

b If there is continuity:

Replace the circuit breaker (3DA2).

(2) If the circuit breaker is open:

Do the procedure (Ref. TSM TASK 24-00-00-810-803).

(a) If the fault continues:

Disconnect the connector from the pitot probe 2 (9DA2) 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):

Replace the PROBE-PITOT 2 (9DA2) 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):

Replace the PHC-2 (6DA2) AMM 30-31-34-000-002 and AMM 30-31-34-400-002.

a If the fault continues:

Do a check and repair the wiring from the PHC 2 (6DA2) pin A/H to the pitot probe 2 (9DA2) pin A/B ASM 303101.

3 If the fault continues:

Do a check for a short to ground at the wiring between the PHC 2 pin A/A and the circuit breaker (3DA2).

a If there is a short to ground:

Repair the related wiring.

b If there is no short to ground:

Replace the C/B-ANTI ICE/PROBES/2/PITOT [3DA2] .

4 If the fault continues:

Replace the PHC-2 [6DA2] AMM 30-31-34-000-002 and AMM 30-31-34-400-002.

Subtask 30-31-00-810-064-E ** ON A/C NOT FOR ALL