Functional Check of the Insulation Resistance of the Pitot Probe Heater

TASK 30-31-00-720-001-A
Functional Check of the Insulation Resistance of the Pitot Probe Heater

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.

CAUTION: REMOVE THE PROTECTIVE COVERS FROM THE PROBES BEFORE YOU DO THE TEST.

ZONE: 120

1. Reason for the Job
Refer to the MPD TASK: 303100-01
FUNCTIONAL CHECK OF THE INSULATION RESISTANCE OF THE PITOT PROBE HEATER
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 3M (10 FT)
No specific	1	AIR SOURCE - REGULATED, FILTERED, DRY
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	1	TESTER - INSULATION RESISTANCE

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
120	AVIONICS COMPARTMENT
FOR [9DA1] (PROBE-PITOT, 1)
FOR [9DA3] (PROBE-PITOT, 3)
812
FOR [9DA2] (PROBE-PITOT, 2)
822

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 30-31-00-710-001-A	Operational Test of the Probe Ice Protection
TASK 34-11-15-000-001-A	Removal of the Pitot Probe
TASK 34-11-15-400-001-A	Installation of the Pitot Probe
Pitot Probe

3. Job Set-up
Subtask 30-31-00-941-064-A

A. Safety Precautions
(1) On the panel 25VU:

Make sure that the PROBE/WINDOW HEAT pushbutton switch is released (the ON legend is off).

Subtask 30-31-00-860-082-A

B. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) Put an ACCESS PLATFORM 3M (10 FT) in position.
(3) Open the access door:
(a) FOR [9DA1] (PROBE-PITOT, 1), [9DA3] (PROBE-PITOT, 3)
812
(b) FOR [9DA2] (PROBE-PITOT, 2)
822.

Subtask 30-31-00-865-145-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 9DA1 (PROBEPITOT, 1)
49VU	ANTI ICE/PROBES/PHC/1	2DA1	D03
49VU	ANTI ICE/PROBES/PITOT/1	3DA1	D02
FOR FIN: 9DA2 (PROBEPITOT, 2)
122VU	ANTI ICE/PROBES/2/PITOT	3DA2	Y14
122VU	ANTI ICE/PROBES/PHC/2	2DA2	Y12
FOR FIN: 9DA3 (PROBEPITOT, 3)
122VU	ANTI ICE/PROBES/PHC/3	2DA3	Y16
122VU	ANTI ICE/PROBES/3/PITOT	3DA3	Z16

4. Procedure

WARNING: ONLY USE THE MEGOHMMETER FOR THE TEST. BEFORE YOU USE THE MEGOHMMETER, MAKE SURE THAT THE PITOT PROBE IS DISCONNECTED. DO NOT TOUCH THE PIN AND THE PITOT BODY GROUND.

Subtask 30-31-00-720-053-A

A. Functional Check of the Insulation Resistance of the Sextant (or Thales) Pitot Probe Heater

CAUTION: MAKE SURE THAT THE ELECTRICAL CONNECTORS ARE CLEAN BEFORE YOU DISCONNECT OR CONNECT THEM. CONTAMINATION ON THE ELECTRICAL CONNECTORS CAN CAUSE DAMAGE TO EQUIPMENT.

(1) Make sure that the external surface is clean and dry.
(2) Make sure that the pitot probe was at ambient temperature not less than one hour before you start the test.
(3) Disconnect the electrical connector (1) from the pitot probe (3).
(4) Use an AIR SOURCE - REGULATED, FILTERED, DRY to blow air into the electrical connector (2) of the pitot probe (3).
(5) Attach one bridge lead of the TESTER - INSULATION RESISTANCE to terminal pin B and the other lead to the pitot probe case.
(6) Apply 50VDC.

Make sure that the resistance is more than 20 megohms.

(a) If the insulation resistance is less than 20 megohms, replace the pitot probe (Ref. AMM TASK 34-11-15-000-001) and (Ref. AMM TASK 34-11-15-400-001).
(b) If the insulation resistance is more than 20 megohms, attach one bridge lead of the TESTER - INSULATION RESISTANCE to terminal pin C and the other lead to the pitot probe case.
(7) Apply 50VDC.

Make sure that the resistance is more than 20 megohms.

(a) If the insulation resistance is less than 20 megohms, replace the pitot probe (Ref. AMM TASK 34-11-15-000-001) and (Ref. AMM TASK 34-11-15-400-001).
(b) If the insulation resistance is more than 20 megohms, connect the electrical connector (1) to the pitot probe (3).

Subtask 30-31-00-720-054-A

B. Functional Check of the Insulation Resistance of the Goodrich-Rosemount Pitot Probe Heater

CAUTION: MAKE SURE THAT THE ELECTRICAL CONNECTORS ARE CLEAN BEFORE YOU DISCONNECT OR CONNECT THEM. CONTAMINATION ON THE ELECTRICAL CONNECTORS CAN CAUSE DAMAGE TO EQUIPMENT.

Make sure that the resistance is more than 100 megohms.

(a) If the insulation resistance is less than 100 megohms, replace the pitot probe (Ref. AMM TASK 34-11-15-000-001) and (Ref. AMM TASK 34-11-15-400-001).
(b) If the insulation resistance is more than 100 megohms, attach one bridge lead of the TESTER - INSULATION RESISTANCE to terminal pin C and the other lead to the pitot probe case.
(7) Apply 500 +/- 10VDC for two minutes.

Make sure that the resistance is more than 100 megohms.

(a) If the insulation resistance is less than 100 megohms, replace the pitot probe (Ref. AMM TASK 34-11-15-000-001) and (Ref. AMM TASK 34-11-15-400-001).
(b) If the insulation resistance is more than 100 megohms, connect the electrical connector (1) to the pitot probe (3).

Subtask 30-31-00-865-146-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.

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.

C. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 9DA1 (PROBEPITOT, 1)
49VU	ANTI ICE/PROBES/PHC/1	2DA1	D03
49VU	ANTI ICE/PROBES/PITOT/1	3DA1	D02
FOR FIN: 9DA2 (PROBEPITOT, 2)
122VU	ANTI ICE/PROBES/2/PITOT	3DA2	Y14
122VU	ANTI ICE/PROBES/PHC/2	2DA2	Y12
FOR FIN: 9DA3 (PROBEPITOT, 3)
122VU	ANTI ICE/PROBES/PHC/3	2DA3	Y16
122VU	ANTI ICE/PROBES/3/PITOT	3DA3	Z16

Subtask 30-31-00-710-062-A

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

5. Close-up
Subtask 30-31-00-860-083-A

A. Put the aircraft back to its initial configuration.
(1) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).
(2) Remove the access platform(s).
(3) Close the access door:
(a) FOR [9DA1] (PROBE-PITOT, 1), [9DA3] (PROBE-PITOT, 3)
812
(b) FOR [9DA2] (PROBE-PITOT, 2)
822.

[Rev.10 from 2021] 2026.04.01 00:30:48 UTC