Cold Weather Maintenance - Water/Waste

TASK 12-31-38-660-001-A
Cold Weather Maintenance - Water/Waste

WARNING: MAKE SURE THAT THE WATER TANK IS DEPRESSURIZED.

CAUTION: MAKE SURE THAT THE DRAIN VALVES STAY IN THE DRAIN POSITION AFTER YOU DRAIN THE POTABLE WATER SYSTEM IF:

THE BLEED AIR SYSTEM IS OFF, AND
THE OUTSIDE AIR TEMPERATURE IS BELOW 0 DEG.C (32 DEG.F).

THIS WILL PREVENT DAMAGE TO THE POTABLE WATER SYSTEM.

CAUTION: BEFORE YOU SUPPLY AIR FROM AN EXTERNAL SOURCE OR THE APU, MAKE CERTAIN THAT :

AT LEAST ONE COCKPIT WINDOW OR CABIN DOOR IS OPEN AND THAT IT REMAINS OPEN DURING SERVICING.
IF THE AIRCRAFT IS PARKED OUTSIDE AND IS NOT PROTECTED FROM THE RAIN ONE MAINTENANCE DOOR OR AVIONICS COMPARTMENT ACCESS DOOR IS OPEN AND THAT IT REMAINS OPEN DURING SERVICING.

1. Reason for the Job
To prevent damage to the water/waste system by ice when the aircraft is not supplied with power or other sources of hot air.

NOTE: Although an aircraft is resistant to very low ambient temperatures, the cabin air conditioning (and WIPU system) keep the pipes (and water systems) sufficiently warm to prevent them from freezing.
However, when the aircraft is not energized or stays on the ground at sub-zero temperatures, you must do additional procedures to prevent damage to the systems by ice.

NOTE: If the service panels or caps are frozen closed, it is necessary not to use force to open or release them. It is necessary to apply hot air.

NOTE: If the SUPPORT WS PANEL DOOR is not available and if fill/drain valve handle is in DRAIN position, the water-service panel door cannot be closed because of a mechanical stop. In this condition, the water-service panel door is not safetied against wind effects. To prevent damage to the water-service panel door in strong wind conditions, the fill/drain valve handle must be put in NORMAL position and the water-service panel door must be closed.

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
98D38108003000	2	SUPPORT WS PANEL DOOR

B. Referenced Information

REFERENCE	DESIGNATION
TASK 12-15-38-613-001-A	Fill the Potable Water Tank System (Aircraft Electrical Power Available)
TASK 12-16-38-613-001-A	Servicing of the Toilet System
TASK 12-24-38-680-001-A	Draining of the Potable Water System (with Electrical Power)
TASK 12-24-38-680-002-A	Draining of the Potable Water System (without Electrical Power)
TASK 38-10-00-614-001-A	Pressurization of the Potable Water System from a Ground Air Supply
TASK 38-10-00-614-002-A	Depressurization of the Potable Water System
TASK 38-10-00-614-003-A	Pressurization of the Potable Water System with the Compressor
TASK 38-31-00-680-001-A	Draining of the Toilet System
TASK 49-00-00-860-005-A	APU Start by External Power
TASK 49-00-00-860-005-A-01	APU Start by Batteries
TASK 49-00-00-860-008-A	APU Start by External Power
TASK 49-00-00-860-008-A-01	APU Start by Batteries

3. Job Set-up
Subtask 12-31-38-941-050-A

A. There is no special job set-up for this task.

4. Procedure
Subtask 12-31-38-660-050-A

A. Pre-Flight (First Flight of the Day)
(1) After draining procedure, because of low ambient temperatures you must obey the steps that follow.
(2) Make sure that all drain valves are closed.
(3) For the potable water system, do the steps that follow:
(a) Fill the potable water system with warm water of 30 deg.C (86.00 deg.F) maximum 30 minutes before the engines start (Ref. AMM TASK 12-15-38-613-001).
(b) Pressurize the potable water system (Ref. AMM TASK 38-10-00-614-001) (Ref. AMM TASK 38-10-00-614-003) and examine the fill/drain valve for leaks.

NOTE: You can pressurize the potable water system with the Auxiliary Power Unit (APU). When you start the APU, the system will start to pressurize automatically (Ref. AMM TASK 49-00-00-860-003) (Ref. AMM TASK 49-00-00-860-008). The system will also automatically pressurize when the primary engines are started.

(c) Remove unwanted quantity of water from around the service panel before you close it.
(4) For the waste system, do the steps that follow:
(a) Pre-charge the waste tanks not more than 30 minutes before the engines start (Ref. AMM TASK 12-16-38-613-001).
(b) Remove unwanted liquid from around the waste service panel before you close it.

Subtask 12-31-38-660-051-A ** ON A/C NOT FOR ALL

B. Post Flight (Last Flight of the Day but not Transit Stops)
(1) General:
(a) Do the servicing of the potable water and the waste water tanks as quickly as possible after the flight.
(b) Read tables 1, 2 and 3 (to drain the potable water system/waste system) and find if it is necessary to drain the waste system and/or the potable water system (refer to the ambient temperature and the cold soak period).
(c) Refer to table 1 for the potable water system and table 2 for the waste water system.
(2) For the potable water system, do the steps that follow:

CAUTION: MAKE SURE THAT THE TEMPERATURE OF THE AIR SUPPLIED BY THE AIRCRAFT BLEEDAIR SYSTEM IS NOT HIGHER THAN 50 DEG.C (122 DEG.F). IF THE AIR IS HOTTER THAN 50 DEG.C (122 DEG.F). IT CAN CAUSE DAMAGE TO THE AIRCRAFT.

(a) Table 1

OUTSIDE AIR TEMPERATURE IN DEG.C (DEG.F)	AIR CONDITIONING OR PRE- CONDITIONED AIR UNIT	CABIN TEMPERATURE IN DEG.C (DEG.F)	EXPOSURE TIME TO WEATHER CONDITIONS IN HOURS:MIN	POTABLE WATER SYSTEM DRAINING REQUIRED	PURGE OF SYSTEM REQUIRED
Between 0 and -15 (32 and 5)	ON	Above 10 (50)	No Time Limit	NO	NO
Below -15 (5)	ON	Above 10 (50)	1:15	YES	NO

NOTE: For other conditions (that is not shown in Table 1), we recommend that you drain the potable water system as quickly as possible after the flight.

NOTE: The exposure time to weather conditions is approximate.

If the aircraft is parked at very low temperature conditions (when the cabin temperature is less than 0 deg.C (32.00 deg.F)), drain and clean the potable water system:
1 Drain the potable water system (Ref. AMM TASK 12-24-38-680-001) or (Ref. AMM TASK 12-24-38-680-002).
2 Close all the lavatory and the galley manual shutoff-valves.
3 Close all the potable water drain and the fill valves.
4 Pressurize the potable water system (Ref. AMM TASK 38-10-00-614-001) or (Ref. AMM D/O 38-10-00-61).

CAUTION: YOU MUST REMOVE THE GALLEY EQUIPMENT THAT IS NOT APPLICABLE FOR THE COLD WEATHER OPERATION. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE GALLEY EQUIPMENT AND THE GALLEY POTABLE-WATER DISTRIBUTION-SYSTEM CAN OCCUR.

5 Remove the remaining water from the potable water system and do the procedure that follows:

NOTE: This procedure is the same for all the lavatories and the galleys that have the potable-water supplied equipment (for example, the water heater, the coffee maker and the water faucets).

a Open the related manual shutoff-valve of the lavatory or galley.
b Operate the water faucets in the galleys to bleed them.
c Make sure that the air (without water) comes out of the water faucet.
d Flush the toilet until the air (without water) comes out of the toilet rinse valve (this part of procedure is applicable to vacuum toilets only).
e Close the related manual shutoff-valve.
f Do this procedure for all the lavatories and the galleys that have potable-water supplied equipment.
6 Do the procedure again frequently as necessary to make sure that the remaining water is fully drained.

NOTE: A minimum of 15 minutes is necessary to do the draining procedure after the flow of water from the potable water system stops. The altitude of the aircraft can cause an effect on the time of the procedure.

NOTE: If the aircraft is moved in less than 1 hour 15 minutes, it is recommended that you put all the drain valve handles in the DRAIN position again. This is to make sure that all the remaining water is drained.

7 Depressurize the potable water system (Ref. AMM TASK 38-10-00-614-002).
8 If necessary, install the 98D38108003000 SUPPORT WS PANEL DOOR on the fill/drain port of the Potable Water Service Panel (PWSP).
9 Put the fill/drain control handle in the DRAIN position to open all the drain valves.

NOTE: If the electrical power is not available, it is recommended that you put the fill/drain control handle in the DRAIN position.

(b) Do not install the caps on the drain and fill/drain port.

NOTE: If you install the caps, the remaining fluid can freeze immediately behind the drain and the fill/drain caps. This can cause:

Damage to the piping system
The system to become unserviceable
The next servicing to not be on time.

(c) If the potable water system is frozen or if it is not possible to drain the potable water system, use the external or internal heat sources as given in Table 3.
(3) For the waste water tank, do the steps that follow:
(a) If the aircraft is parked at very low temperature conditions (when the cabin temperature is less than 0 deg.C (32.00 deg.F)), drain and clean the waste water tank:
1 Do the servicing of the toilet system (Ref. AMM TASK 12-16-38-613-001).
2 Remove the remaining water from the waste water system as follows:
a Put the toilet drain-valve control-handle in the DRAIN position to open all the drain valves and let the remaining fluid flow out.
b Do not close the caps on the toilet drain and fill/rinse connections.

NOTE: If you close the caps, the remaining fluid can freeze immediately behind the toilet drain and the fill/rinse caps. This can cause:

Damage to the piping system
The system to become unserviceable
The next servicing to not be on time.

Subtask 12-31-38-660-052-B ** ON A/C NOT FOR ALL

C. Post Flight (Last Flight of the Day but not Transit Stops)
(1) General:
(a) Do the servicing of the potable water and the waste water tanks as quickly as possible after the flight.
(b) Read tables 1, 2 and 3 (to drain the potable water system/waste system) and find if it is necessary to drain the waste system and/or the potable water system.
(c) Refer to table 1 for the potable water system and table 2 for the waste water system.
(2) For the potable water system, do the steps that follow:

(a) Table 1

OUTSIDE AIR TEMPERATURE IN DEG.C (DEG.F)	AIR CONDIT IONING OR PRE- CONDITI ONED AI R UNIT	CABIN TEMPERA TURE IN DEG.C (DEG.F)	DEPRES SURIZATION SYSTEM	EXPOSURE TIME TO WEATHER CONDITIONS IN HOURS:MIN	POTABLE WATER SYSTEM DRAINING REQUIRED
Between 0 and -15 (32 and 5)	ON	Above 10 (50)	OFF	No Time Limit	NO
Below -15 (5)	ON	Above 10 (50)	OFF	1:15	YES

NOTE: For other conditions (that is not shown in Table 1), we recommend that you drain the potable water system as quickly as possible after the flight.

NOTE: The exposure time to weather conditions is approximate.

NOTE: If a depress option is installed and started, you can stop the air conditioning and ignore the cabin temperature.

If the aircraft is parked at very low temperature conditions (when the cabin temperature is less than 0 deg.C (32.00 deg.F)), drain and clean the potable water system.
(b) Use the depressurization system as follows:
1 On FAP 120RH, push the membrane switch 'WATER DEPR':

The light in the membrane switch comes on.
Keep the aircraft power on to use the potable-water heating system.

(c) If you do not use the depressurization system, drain and clean the potable water system as follows:
1 Drain the potable water system (Ref. AMM TASK 12-24-38-680-001) or (Ref. AMM TASK 12-24-38-680-002).
2 Close all the lavatory and the galley manual shutoff-valves.
3 Close all the potable water drain and the fill valves.
4 Pressurize the potable water system (Ref. AMM TASK 38-10-00-614-001) or (Ref. AMM TASK 38-10-00-614-003).

5 Remove the remaining water from the potable water system and do the procedure that follows:

NOTE: This procedure is the same for all the lavatories and the galleys that have the potable-water supplied equipment (for example, the water heater, the coffee maker and the water faucets).

a Open the related manual shutoff-valve of the lavatory or galley.
b Operate the water faucet (HOT and COLD).
c Make sure that the air (without water) comes out of the water faucet.
d Flush the toilet until the air (without water) comes out of the toilet rinse valve.
e Close the related manual shutoff-valve.
f Do this procedure for all the lavatories and the galleys that have potable-water supplied equipment.
6 Open the manual shutoff valves in all the galleys and the lavatories.
7 Do the procedure again frequently as necessary to make sure that the remaining water is fully drained.

8 Depressurize the potable water system (Ref. AMM TASK 38-10-00-614-002).
9 If necessary, install the 98D38108003000 SUPPORT WS PANEL DOOR on the fill/drain port of the Potable Water Service Panel (PWSP).
10 Put the fill/drain control handle in the DRAIN position to open all the drain valves.

NOTE: If the electrical power is not available, it is recommended that you put the fill/drain control handle in the DRAIN position.

(d) Do not install the caps on the drain and fill/drain port.

NOTE: If you install the caps, the remaining fluid can freeze immediately behind the drain and the fill/drain caps. This can cause:

Damage to the piping system
The system to become unserviceable
The next servicing to not be on time.

(e) If the potable water system is frozen or starts to freeze (before you use the depressurization system or drain it), use the external or internal heat sources as given in Table 3.
(3) For the waste water tank, do the steps that follow:
(a) If the aircraft is parked at very low temperature conditions (when the cabin temperature is less than 0 deg.C (32.00 deg.F)), drain and clean the waste water tank:
1 Drain the toilet system (Ref. AMM TASK 38-31-00-680-001).
2 Remove the remaining water from the waste water system as follows:
a Put the toilet drain-valve control-handle in the OPEN position and let the remaining fluid flow out.
b Do not close the caps on the toilet drain and fill/rinse connections.

NOTE: If you close the caps, the remaining fluid can freeze immediately behind the toilet drain and the fill/rinse caps. This can cause:

Damage to the piping system
The system to become unserviceable
The next servicing to not be on time.

Subtask 12-31-38-660-053-A

D. Waste System Drain
Table 2

OUTSIDE AIR TEMPERATURE IN DEG.C (DEG.F)	AIR CONDITIONING	CABIN TEMPERATURE IN DEG.C (DEG.F)	EXPOSURE TIME TO WEATHER CONDITIONS IN HOURS:MIN	WASTE SYSTEM DRAINING REQUIRED
Between 0 and -15 (32 and 5)	ON	Above 10 (50)	No Time Limit	NO
Below -15 (5)	ON	Above 10 (50)	1:15	YES
Between 0 and -7 (38 and 19)	OFF		1:30	YES
Between -7 and -15 (19.4 and 5)	OFF		0:30	YES
Below -15 (5)	OFF		None	YES

NOTE: The exposure time to weather conditions is approximate.

Subtask 12-31-38-660-054-A

E. Cold Weather Maintenance
Table 3

OUTSIDE AIR TEMPERATURE IN DEG.C (DEG.F)	EXTERNAL HEAT SOURCE	APU	DRAINING OF WATER SYSTEM
0 to -5 (32 to 23)	1 Hour Every 4 Hours	NO	NO
-5 to -10 (23 to 14)	2 Hours Every 4 Hours	NO	NO
-10 to -15 (14 to 5)	Continuous	NO	NO
Below -15 (5)	Continuous	As Required	YES

[Rev.10 from 2021] 2026.04.01 04:22:19 UTC