(B)  
The APU is the most likely source of the smoke or odors.  An APU failure can release oil into the air conditioning system.  Oil, glycol, or hydraulic fluid ingested into the inlet of the APU is another possible source of the contamination.

(C)  
Once oil has entered the pneumatic and/or air conditioning system, it tends to accumulate in the heat exchangers or precoolers.  The oil, hydraulic fluid, or glycol vaporizes at higher temperatures and enters the cabin.

(D)  
Do not do this procedure with the crew and passengers on board, since this procedure generates a high concentration of smoke.

2.  Removal of Oil Contamination from the Air Conditioning and Pneumatic Systems
A.  References
(1)  
21-31-0, Pressurization Control Systems - Maintenance Practices

(2)  
21-51-41, Water Separator Coalescer (Bag) - Cleaning/Painting

(3)  
24-22-0, Manual Control

(4)  
36-11-41, Pneumatic Ground Service Connector

(5)  
49-11-0, APU Power Plant - Maintenance Practices

(6)  
71-09-100, Power Plant - Operating Procedure

B.  Access
(1) 
 Location Zone
101    Control Cabin - Left
102    Control Cabin - Right
212    Left Air Conditioning Equipment Bay
214    Right Air Conditioning Equipment Bay

(2)  
Access Panels
3303L      A/C Access Panel
3403R      A/C Access Panel

C.  Procedure
(1)  
Open the access doors to the air conditioning bays.

(2)  
Remove the water separators (Ref 21-51-41).

(3)  
Clean the coalescer bags for the water separators (Ref 21-51-41).

(4)  
Install the water separators (Ref 21-51-41).

(5)
Clean the pneumatic ducts and the components where you can see the oil contamination.

(6)
Replace the components that have too much contamination.

(7)
Supply electrical power (Ref 24-22-00 MP).

(8)
Make sure these switches are set to OFF at the P5-10 panel:

(a)
L and R PACK switches

(b)
APU BLEED switch

(c)
BLEED 1 and BLEED 2 switches

(d)
GASPER FAN switch

(9)
Make sure the ISOLATION VALVE switch on the P5 overhead panel is set to OPEN.

(10)
Remove the check valve at the pneumatic ground connector (Ref/ 36-11-41).

NOTE:  This will permit the initial bleed air, which has more oil contamination, to go out through the check valve opening.

(11)
Pressurize the APU pneumatic duct:

501 
May 01/03  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  21-00-01 Page 201 

WARNING:  DO NOT GO NEAR THE CHECK VALVE WHEN YOU PRESSURIZE THE APU PNEUMATIC DUCT.  THE APU BLEED AIR CAN CAUSE INJURY TO PERSONS WHEN THE BLEED AIR GOES OUT THROUGH THE CHECK VALVE OPENING.
NOTE:  This procedure will remove the oil contamination from the APU bleed air. The APU bleed air will go out through the check valve opening.
(a)
Start the APU and let the operation of the APU become stable (Ref 49-11-0).

(b)
Put the APU BLEED switch to ON.

NOTE:  The APU bleed air shutoff valve opens and the bleed air goes out through the check valve opening.

(c)
Let the APU operate until the APU bleed air has no smell of the oil contamination.

(d)  
Put the APU BLEED switch to OFF.

NOTE:  The APU bleed air shutoff valve closes.

(e)  
Stop the APU (Ref 49-11-0).

501 
21-00-01 Page 202  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 01/03 

(12)
Install the check valve which you removed from the pneumatic ground connector (Ref 36-11-41).

(13)
Start the APU again (Ref 49-11-0).

(14)
Set the APU BLEED switch to ON.

(15)
Operate the air conditioning packs:

NOTE:  This procedure uses the APU bleed air to remove the oil from the air conditioning system.
(a)  
Make sure the aft outflow valve is open (Ref 21-31-0) or at least one passenger entry door is open.

WARNING:  MAKE SURE THERE IS AN EXIT FOR THE CONDITIONED AIR IN THE AIRPLANE.  ACCIDENTAL CABIN PRESSURIZATION CAN CAUSE INJURY TO PERSONS.

(b)  
Set the position of these switches on the P5-10 panel as follows:
1) ISOLATION VALVE to OPEN
2) L PACK and R PACK switches to AUTO
3) GASPER FAN switch to ON
　
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