(b)  
Open the access door to the ground air connector for the pneumatic system.

501 
Feb 01/96  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  21-51-21 Page 701 

F56407
Heat Exchanger Reverse Flusher Installation  501 
21-51-21  Figure 701  Feb 01/96 
Page 702 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

(c)  
Install the check valve deactivator tool in the ground air connector.

WARNING:  WEAR GLOVES THAT WILL GIVE YOU PROTECTION FROM HOT SURFACES WHEN YOU CONNECT OR DISCONNECT PNEUMATIC FITTINGS. THE GROUND AIR CONNECTOR CAN BE VERY HOT IF THE PACKS HAVE BEEN OPERATED IMMEDIATELY BEFORE THIS PROCEDURE. YOU CAN BADLY BURN YOUR HANDS IF YOU TOUCH A HOT GROUND AIR CONNECTOR.

(d)  
Install a pneumatic hose from the ground air connector to the fitting on the bottom of the reverse flusher.

(e)  
Start the APU (Ref 49-11-0/201).

CAUTION:  DO NOT LET THE PRESSURE IN THE REVERSE FLUSHER BE MORE THAN 2.5 PSIG. THE RAM AIR DUCT COULD BE DAMAGED FROM PRESSURES MORE THAN 2.5 PSIG.

(f)  
Set the APU BLEED switch to ON.

(g)  
Set the APU BLEED switch to OFF when the container of the detergent is empty.

CAUTION:  DO NOT PERMIT APU BLEED AIR WITHOUT THE SOAP SOLUTION TO GO THROUGH THE RAM AIR DUCTS. WITHOUT THE SOAP SOLUTION TO DECREASE THE TEMPERATURE OF THE APU BLEED AIR, DAMAGE TO THE RAM AIR DUCTS CAN OCCUR.

(h)  
Let the detergent stay on the heat exchangers for a minimum of 5 minutes.

(i)  
Flush the heat exchangers as follows: 1) Fill the container with water. 2) Set the APU BLEED switch to ON to flush the detergent and the contamination

from the heat exchangers. 3) Set the APU BLEED switch to OFF when the container of water is empty.
CAUTION:  DO NOT PERMIT APU BLEED AIR WITHOUT WATER TO GO THROUGH THE RAM AIR DUCTS. WITHOUT THE WATER TO DECREASE THE TEMPERATURE OF THE APU BLEED AIR, DAMAGE TO THE RAM AIR DUCTS CAN OCCUR.
4)  Do the steps above again until all of the detergent is flushed from the heat exchangers.
(j)  
Stop the APU (Ref 49-11-0/201).

(k)  
Look at the gage on the reverse flusher and make sure the pressure is 0 psig.

(l)  
Remove the pneumatic hose from the ground air connector and the reverse flusher.

WARNING:  WEAR GLOVES THAT WILL GIVE YOU PROTECTION FROM HOT SURFACES WHEN YOU CONNECT OR DISCONNECT PNEUMATIC FITTINGS. THE GROUND AIR CONNECTOR CAN BE VERY HOT IF THE PACKS HAVE BEEN OPERATED IMMEDIATELY BEFORE THIS PROCEDURE. YOU CAN BADLY BURN YOUR HANDS IF YOU TOUCH A HOT GROUND AIR CONNECTOR.

(m)  
Remove the check valve deactivator tool from the ground air connector.

(n)  
Close the access door to the ground air connector.

501 
Feb 01/96  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  21-51-21 Page 703 

D.  Clean the Heat Exchangers with a High Pressure Ground Cart as the Pneumatic Source
(1)  Use a high-pressure ground cart as the pneumatic source to clean the heat exchangers as follows:
(a)  
Install a pneumatic hose from the ground cart to the fitting on the bottom of the reverse flusher.

WARNING:  WEAR GLOVES THAT WILL GIVE YOU PROTECTION FROM HOT SURFACES WHEN YOU CONNECT OR DISCONNECT PNEUMATIC FITTINGS. THE BLEED AIR FITTING ON THE GROUND CART CAN BE VERY HOT IF THE GROUND CART HAS BEEN OPERATED IMMEDIATELY BEFORE THIS PROCEDURE. YOU CAN BADLY BURN YOUR HANDS IF YOU TOUCH A HOT FITTING ON THE GROUND CART.

(b)  
Set the bleed switch on the ground cart to on.

(c)  
Open the bleed air valve on the ground cart.

CAUTION:  DO NOT LET THE PRESSURE IN THE REVERSE FLUSHER BE MORE THAN 2.5 PSIG. THE RAM AIR DUCT COULD BE DAMAGED FROM PRESSURES MORE THAN 2.5 PSIG.

(d)  
Set the bleed switch on the ground cart to off when the container of detergent is empty.

CAUTION:  DO NOT PERMIT HOT AIR FROM THE GROUND CART WITHOUT THE DETERGENT TO GO THROUGH THE RAM AIR DUCTS. WITHOUT THE DETERGENT TO DECREASE THE TEMPERATURE OF THE HOT AIR, DAMAGE TO THE RAM AIR DUCTS CAN OCCUR.

(e)  
Let the detergent stay on the heat exchangers for a minimum of 5 minutes.

(f)  
Flush the heat exchangers as follows: 1) Fill the container with water. 2) Set the bleed switch on the ground cart to on to flush the detergent and the

contamination from the heat exchangers.
501 
　
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