Removal of the Probe Heat Computer (PHC)

TASK 30-31-34-000-002-A
Removal of the Probe Heat Computer (PHC)

WARNING: MAKE SURE THAT CIRCUIT BREAKERS 2KS1 AND 2KS2 ARE CLOSED BEFORE YOU OPEN 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.

WARNING: BEFORE YOU OPEN PHC CIRCUIT BREAKERS 2DA1(2,3), OPEN 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 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
No specific	AR	CAP - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

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

C. Referenced Information

REFERENCE	DESIGNATION
PHC Backshell Connector

3. Job Set-up
Subtask 30-31-34-865-051-A

A. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 6DA1 (PHC1)
49VU	ANTI ICE/PROBES/AOA/1	4DA1	D04
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/2/STATIC	5DA2	Y11
FOR FIN: 6DA3 (PHC3)
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 30-31-34-865-054-A

B. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 6DA1 (PHC1)
49VU	ANTI ICE/PROBES/PHC/1	2DA1	D03
FOR FIN: 6DA2 (PHC2)
122VU	ANTI ICE/PROBES/PHC/2	2DA2	Y12
FOR FIN: 6DA3 (PHC3)
122VU	ANTI ICE/PROBES/PHC/3	2DA3	Y16

Subtask 30-31-34-010-050-A

C. Get Access
(1) Put the ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE in position.
(2) Open the access door 811.

4. Procedure
Subtask 30-31-34-020-050-A

A. Removal of the PHC

PHC Backshell Connector

(1) Disconnect the electrical connector (4) from the PHC (3).
(2) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(3) Remove the screws (1) and the washers (2).
(4) Remove the PHC (3).

[Rev.10 from 2021] 2026.04.01 00:30:49 UTC