757
MAINTENANCE MANUAL
AIR CONDITIONING SYSTEM OIL CONTAMINATION (REMOVAL) - MAINTENANCE PRACTICES
___________________________________________________________________________
1. General
_______
A. This procedure has the steps to remove the oil contamination from the air conditioning and pneumatic systems. You must first isolate the cause of the oil contamination and repair the problem before you do this procedure.
B. The oil fumes and the smoke from an APU/engine failure can get into the airplane cabin and cause contamination of the conditioned air.
C. The APU is the most likely source of the smoke or odors. Any 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.
D. When oil enters the pneumatic and/or air conditioning system, it tends to accumulate in the heat exchangers or the precoolers. The oil, hydraulic fluid, or the glycol vaporizes at a higher temperature and enters the cabin.
E. Do not do this procedures with the crew and passengers on board, since this procedure generates a high concentration of smoke.
F. Do not do this procedures with the crew on board, since this procedure generates a high concentration of smoke.
TASK 21-00-01-002-001
2. Removal of Oil Contamination from the Air Conditioning and Pneumatic Systems
_____________________________________________________________________________
A. References
(1)
AMM 24-22-00/201, Manual Control
(2)
AMM 36-11-03/401, Pneumatic Ground Connector
(3)
AMM 36-00-00/201, Pneumatic System
(4)
AMM 49-11-00/201, Auxiliary Power Unit
(5)
AMM 71-00-00/201, Power Plant
B.
Access
(1)
Location Zone
135 Environmental Control System Bay, L
136 Environmental Control System Bay, R
211 Control Cabin - L
212 Control Cabin - R
(2)
Access Panels
193HL Environmental Control System Bay, L
194ER Environmental Control System Bay, R
C.
Procedure
(1)
Open the access doors to the air conditioning bays.
S 162-003
(2)
Clean the pneumatic ducts and the components where you can see the oil contamination.
S 012-002
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21-00-01
ALL ú ú 01 Page 201 ú May 28/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
S 962-004
(3) Replace the components if they have too much contamination.
S 862-005
(4) Supply electrical power (AMM 24-22-00/201).
S 862-006
(5) Make sure these switches are set to OFF on the overhead P5 panel:
(a) L and R PACK.
(b) APU.
(c) TRIM AIR.
(d) L and R RECIRC FAN.
S 862-007
(6) Make sure the ISOLATION valve switch on the overhead P5 panel is set
to ON (open).
S 022-008
(7) Remove the check valve at the pneumatic ground connector on the
right side of the airplane (AMM 36-11-03/401).
NOTE:____ this will permit the initial bleed air, which has more oil
contamination, to go out through the check valve opening.
S 862-026
WARNING: DO NOT GO NEAR THE CHECK VALVES 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.
(8) Pressurize the pneumatic duct:
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 (AMM 49-11-00/201).
(b)
Put the APU switch to ON.
(c)
Let the APU operate until the APU bleed air has no smell of the oil contamination.
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