Installation of the Probe Heat Computer (PHC)

TASK 30-31-34-400-002-A
Installation of the Probe Heat Computer (PHC)

WARNING: MAKE SURE THAT CIRCUIT BREAKERS 2KS1 AND 2KS2 ARE CLOSED BEFORE YOU CLOSE PROBE HEATER CIRCUIT-BREAKERS 1DA1(2), 3DA1(2,3), 4DA1(2,3) AND 5DA1(2,3). IF YOU DO NOT OBEY THIS INSTRUCTION: - THE PROBES WILL BECOME TOO HOT. - THIS CAN CAUSE DAMAGE TO EQUIPMENT AND INJURY TO MAINTENANCE PERSONNEL.

ZONE: 121
ZONE: 122
FIN: 6DA1
FIN: 6DA2
FIN: 6DA3

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

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
121	AVIONICS COMPARTMENT
122	AVIONICS COMPARTMENT
811

C. Referenced Information

REFERENCE	DESIGNATION
TASK 30-31-00-710-001-A	Operational Test of the Probe Ice Protection
PHC Backshell Connector
Orientation of the Backshell

3. Job Set-up
Subtask 30-31-34-865-052-A

WARNING: MAKE SURE THAT THE PROBE HEATER CIRCUIT-BREAKERS 1DA1(2), 3DA1(2,3), 4DA1(2,3) AND 5DA1(2,3) ARE OPEN BEFORE YOU OPEN THE PHC CIRCUIT BREAKERS 2DA1(2,3). IF YOU DO NOT OBEY THIS PRECAUTION, THE PROBES WILL BECOME TOO HOT. THIS CAN CAUSE INJURY TO MAINTENANCE PERSONNEL AND/OR DAMAGE TO EQUIPMENT.

A. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 6DA1 (PHC1)
49VU	ANTI ICE/PROBES/AOA/1	4DA1	D04
49VU	ANTI ICE/PROBES/PHC/1	2DA1	D03
49VU	ANTI ICE/PROBES/PITOT/1	3DA1	D02
122VU	ANTI ICE/PROBES/1/STATIC	5DA1	Z13
122VU	ANTI ICE/PROBES/1/TAT	1DA1	Z12
FOR FIN: 6DA2 (PHC2)
122VU	ANTI ICE/PROBES/2/TAT	1DA2	Y15
122VU	ANTI ICE/PROBES/2/PITOT	3DA2	Y14
122VU	ANTI ICE/PROBES/2/AOA	4DA2	Y13
122VU	ANTI ICE/PROBES/PHC/2	2DA2	Y12
122VU	ANTI ICE/PROBES/2/STATIC	5DA2	Y11
FOR FIN: 6DA3 (PHC3)
122VU	ANTI ICE/PROBES/PHC/3	2DA3	Y16
122VU	ANTI ICE/PROBES/3/PITOT	3DA3	Z16
122VU	ANTI ICE/PROBES/3/AOA	4DA3	Z15
122VU	ANTI ICE/PROBES/3/STATIC	5DA3	Z14

Subtask 30-31-34-010-051-A

B. Make sure that the ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE is in position.
(1) Make sure that the access door 811 is open.

4. Procedure
Subtask 30-31-34-420-050-A

A. Installation of the PHC

PHC Backshell Connector

Orientation of the Backshell

(1) Install the PHC (3).
(2) Install the screws (1) and the washers (2).
(3) Tighten the screws (1).
(4) Remove the CAP-BLANKING from each electrical connector and receptacle.

CAUTION: DO NOT TWIST OR BEND THE ELECTRICAL HARNESS WHEN YOU DISCONNECT/CONNECT THE ELECTRICAL CONNECTOR. IF YOU DO, YOU CAN CAUSE DAMAGE TO THE HARNESS AND THUS CAUSE ELECTRICAL CIRCUIT DEFECTS.

(5) Turn the position of the backshell in relation to the PHC according to the ESPM 20-33-45 and connect the electrical connector (4).

NOTE: Obey the rules in the ESPM 20-33-11 to prevent the electrical harness stress, twist or wrong bend radius.

Subtask 30-31-34-865-053-A

WARNING: CLOSE THE PHC CIRCUIT BREAKERS 2DA1(2,3) BEFORE YOU CLOSE THE PROBE HEATER CIRCUIT-BREAKERS 1DA1(2), 3DA1(2,3), 4DA1(2,3) AND 5DA1(2,3). IF YOU DO NOT OBEY THIS SEQUENCE, THE PROBES WILL BECOME TOO HOT. THIS CAN CAUSE INJURY TO MAINTENANCE PERSONNEL AND/OR DAMAGE TO EQUIPMENT.

B. Remove the safety clips and tags and close these circuit breakers in this sequence:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 6DA1 (PHC1)
49VU	ANTI ICE/PROBES/PHC/1	2DA1	D03
122VU	ANTI ICE/PROBES/1/TAT	1DA1	Z12
49VU	ANTI ICE/PROBES/PITOT/1	3DA1	D02
49VU	ANTI ICE/PROBES/AOA/1	4DA1	D04
122VU	ANTI ICE/PROBES/1/STATIC	5DA1	Z13
FOR FIN: 6DA2 (PHC2)
122VU	ANTI ICE/PROBES/PHC/2	2DA2	Y12
122VU	ANTI ICE/PROBES/2/TAT	1DA2	Y15
122VU	ANTI ICE/PROBES/2/PITOT	3DA2	Y14
122VU	ANTI ICE/PROBES/2/AOA	4DA2	Y13
122VU	ANTI ICE/PROBES/2/STATIC	5DA2	Y11
FOR FIN: 6DA3 (PHC3)
122VU	ANTI ICE/PROBES/PHC/3	2DA3	Y16
122VU	ANTI ICE/PROBES/3/PITOT	3DA3	Z16
122VU	ANTI ICE/PROBES/3/AOA	4DA3	Z15
122VU	ANTI ICE/PROBES/3/STATIC	5DA3	Z14

Subtask 30-31-34-710-050-A

C. Do an operational test of the probe ice protection system (Ref. AMM TASK 30-31-00-710-001).

5. Close-up
Subtask 30-31-34-410-050-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the access door 811.
(3) Remove the access platform(s).

[Rev.10 from 2021] 2026.04.01 00:30:51 UTC