Pre-conditioning through the Low Pressure SUBFREEZING PCA GROUND-AIR SUPPLY

TASK 12-33-21-618-002-A
Pre-conditioning through the Low Pressure SUBFREEZING PCA GROUND-AIR SUPPLY

WARNING: MAKE SURE THAT DURING THIS PROCEDURE THE AIRCRAFT IS IN ONE OF THESE THREE CONDITIONS:

THE CABIN PRESSURE OUTFLOW VALVE IS OPEN.
THE FWD AVIONICS COMPARTMENT ACCESS DOOR 811 IS OPEN.
ONE OR MORE PASSENGER DOORS ARE OPEN.

YOU MUST ATTACH A WARNING NOTICE TO THE OPEN DOORS TO TELL PERSONS NOT TO CLOSE THEM. THIS PREVENTS ACCIDENTAL PRESSURIZATION OF THE AIRCRAFT.

CAUTION: MAKE SURE THAT:

THE OUTLET TEMPERATURE OF THE SUBFREEZING GROUND AIR SUPPLY UNIT IS NOT LESS THAN -10 DEG. C (14 DEG. F)
THE STATIC PRESSURE AT THE AIRCRAFT CONNECTOR IS LESS THAN 40 MBAR (0.58 PSI). IF THE VALUES ARE NOT IN THESE LIMITS, DAMAGE TO THE AIR CONDITIONING SYSTEM CAN OCCUR.

CAUTION: DO NOT USE CONDITIONED AIR FROM THE APU OR HIGH-PRESSURE GROUND UNIT AT THE SAME TIME AS AIR FROM THE LOW-PRESSURE GROUND UNIT. IF YOU DO NOT OBEY THIS PRECAUTION, DAMAGE TO THE CHECK VALVES OR THE AIRCRAFT CAN OCCUR.

CAUTION: MAKE SURE THAT THE GROUND AIR-SUPPLY UNIT IS NOT TOO NEAR THE AIRCRAFT AND THAT THE ENGINE EXHAUST PIPE OF THE GROUND AIR- SUPPLY UNIT POINTS AWAY FROM THE AIRCRAFT. HEAT FROM THIS UNIT AND FROM THE EXHAUST CAN CAUSE DAMAGE TO THE AIRCRAFT STRUCTURE.

CAUTION: DURING PRE-CONDITIONING WITH THE GROUND-AIR SUPPLY UNIT, MAKE SURE THAT THE ELECTRICAL GROUND POWER UNIT IS ON AND CORRECTLY CONNECTED TO THE AIRCRAFT. IF YOU DO NOT OBEY THIS PRECAUTION, THE RECIRCULATION FANS CAN STOP OPERATION AND DAMAGE TO THE AIRCRAFT CAN OCCUR.

CAUTION: MAKE SURE THAT THE SUBFREEZING PRE-CONDITIONING UNIT THAT YOU USE ON THE AIRCRAFT COMPLIES WITH THE "SUBFREEZING PCA CARTS - COMPLIANCE DOCUMENT FOR SUPPLIERS". THIS DOCUMENT TELLS YOU HOW TO MAKE SURE THAT YOUR SUBFREEZING AIR PRE-CONDITIONING EQUIPMENT IS COMPATIBLE WITH AIRBUS AIRCRAFT.

1. Reason for the Job
Pre-conditioning with a SUBFREEZING PCA Ground-Air Supply Unit through the Low Pressure Ground Connection.
The SUBFREEZING PCA ground-air supply unit supplies air to the cabin with a temperature below the freezing point during operation in hot weather conditions.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 2M (6 FT)
No specific	1	GROUND AIR-SUPPLY UNIT(LOW PRESSURE)
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
191CB, 811

C. Referenced Information

REFERENCE	DESIGNATION
TASK 12-33-21-618-001-A	Pre-conditioning through the LP Ground Connection (Aircraft Electrical Power Available)
TASK 12-33-21-618-001-A-01	Pre-conditioning through the HP Ground Connection
TASK 12-33-21-618-001-A-02	Pre-conditioning with the APU
TASK 12-33-21-618-001-A-03	Pre-conditioning through the LP Ground Connection (Aircraft Electrical Power Not Available)
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 31-60-00-860-001-A	EIS Start Procedure
LP and HP Ground Connectors
Subfreezing Pull-Down Phase
Subfreezing, Cooling Phase before Boarding
Subfreezing, Cooling Phase during Boarding

3. Job Set-up
Subtask 12-33-21-861-053-A

A. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) Do the EIS start procedure (upper ECAM DU and lower ECAM DU only)
(Ref. AMM TASK 31-60-00-860-001).
(3) On the overhead panel, on the AIR COND section on control panel 30VU:
(a) Set ENG 1/2 BLEED and PACK 1/2 pushbutton switches to the OFF position (the OFF legends come on).
(b) Make sure that the ON legend in the APU BLEED pushbutton switch is off.
(c) Put a WARNING NOTICE(S) in position to tell persons not to operate these switches.
(4) On the overhead panel, on the VENTILATION section on control panel 22VU:
(a) Make sure that the CAB FANS pushbutton switch is pushed (the OFF legend is off) and that each fan operates.
(5) If one of the cabin fans does not operate, do the pre-conditioning with the low-pressure ground-air supply unit (Ref. AMM TASK 12-33-21-618-001).

Subtask 12-33-21-010-061-A

B. Get Access

LP and HP Ground Connectors

(1) Open access door 191CB.
(2) Connect the SUBFREEZING PCA GROUND AIR-SUPPLY UNIT(LOW PRESSURE) to the aircraft low-pressure ground connector.

Subtask 12-33-21-941-056-A

C. Do one of these safety precautions:
(1) Make sure that the cabin pressure outflow valve is open.
(a) On the overhead panel, on the CABIN PRESS section on the control panel 25VU:

Put a warning notice in position to tell persons not to close the outflow valve.

(2) Or make sure that one cabin door is in the open position.
(a) Put a WARNING NOTICE(S) in position to tell persons not to close the cabin door.
(3) Or make sure that forward avionics compartment access door 811 is in the open position.
(a) Put the ACCESS PLATFORM 2M (6 FT) in position below forward avionics compartment access door 811.
(b) Open forward avionics compartment access door 811.

4. Procedure
Subtask 12-33-21-618-069-A

A. Pre-conditioning with a SUBFREEZING PCA ground-air supply unit through the Low Pressure (LP) ground connection.

NOTE: Two persons are necessary to do this task.

NOTE: Make sure that the SUBFREEZING PCA ground-air supply unit complies with the functional requirements, which are specified in the Airbus document
"SUBFREEZING PCA CARTS - COMPLIANCE DOCUMENT FOR SUPPLIERS".
(Contact AIRBUS to get this document.)

NOTE: Obey the instructions for the SUBFREEZING PCA ground-air supply unit and operate the ground-air supply unit in the specified limits.

NOTE: Make sure that the cabin crew and the ground cart operator can speak to each other to control the temperature in the cabin.

(1) Start the SUBFREEZING PCA ground-air supply unit and make sure that:

The airflow is not more than 60 kg.min (132.28 lb.min),
The supplied air pressure is not more than 40 mbar (0.58 psi) at the aircraft LP ground connector.
The water mass fraction value of the supplied air is not more than 2 gr of water per 1 kg of dry air.

(2) Set the necessary outlet temperature on the SUBFREEZING PCA ground-air supply unit and make sure that:

The temperature of the supplied air does not increase to more than 70 deg.C (158.00 deg.F).
The temperature of the supplied air does not decrease to less than -10 deg.C (14.00 deg.F).

(3) Start the defrost cycle.

NOTE: If the air from the SUBFREEZING PCA ground-air supply unit is less than 0 deg.C (32.00 deg.F), you must do the defrost cycle:

At the start of the pre-conditioning procedure,
After that, in intervals of 20 minutes during the procedure.

(a) Operate the SUBFREEZING PCA ground-air supply unit for 4 minutes with

an airflow of 60 kg.min (132.28 lb.min),
an outlet temperature at the LP ground connector of more than 10 deg.C (50.00 deg.F).

(4) On the Flight Attendant Panel (FAP) or the ECAM control panel, monitor the average cabin temperature.
(a) If the average cabin temperature is more than 27 deg.C (80.60 deg.F), continue with para.(5).
(b) If the average cabin temperature is 27 deg.C or less, continue with para.(6) and start the cooling phase before the boarding procedure.

(5) Start the pull-down cooling phase.

NOTE: Do not adjust the PCA outlet temperature to less than the value given in the diagram.

(a) Operate the SUBFREEZING PCA ground-air supply unit with an airflow of 60 kg.min (132.28 lb.min).
(b) Refer to the diagram and adjust the PCA outlet temperature at the LP ground connector to the applicable value.

Subfreezing Pull-Down Phase

(c) If the average cabin temperature decreases to 27 deg.C (80.60 deg.F) or less, then continue with para. (6).

(6) Start the cooling phase before the boarding procedure.
(a) Operate the SUBFREEZING PCA ground-air supply unit with an airflow of 60 kg.min (132.28 lb.min).
(b) Refer to the diagram and adjust the PCA outlet temperature at the LP ground connector to the applicable value.

Subfreezing, Cooling Phase before Boarding

(7) Start the cooling phase during the boarding procedure.

NOTE: Do not adjust the PCA outlet temperature to less than the value given in the diagram.

Subfreezing, Cooling Phase during Boarding

Subtask 12-33-21-618-070-A

B. When the pre-conditioning is no longer necessary, stop the SUBFREEZING PCA ground-air supply unit.

NOTE: Obey the instructions given with the ground-air unit.

5. Close-up
Subtask 12-33-21-410-060-A

A. Close Access
(1) Disconnect and remove the SUBFREEZING PCA ground-air supply unit from the aircraft LP ground connection.
(2) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(3) Close access door 191CB.
(4) Close forward avionics compartment access door 811, if necessary.
(5) Remove the WARNING NOTICE(S).
(6) Put the aircraft back to its initial configuration.

[Rev.10 from 2021] 2026.04.02 06:47:45 UTC