(2)
On the panel 25VU, make sure that the APU MASTER SW pushbutton switch is off.
(3)
Put a warning notice in the cockpit to tell persons not to start the APU.
(4)
Make sure that hydraulic systems are depressurized
(Ref. TASK 29-00-00-864-001).
Subtask 49-91-44-865-066
B. Open, safety and tag this(these) circuit breaker(s):
-------------------------------------------------------------------------------PANEL DESIGNATION IDENT. LOCATION -------------------------------------------------------------------------------121VU APU/APU/CTL 2KD L42 121VU APU/ECB/SPLY 1KD L41
Subtask 49-91-44-010-057
C. Get Access
(1)
Put the access platform in position below the APU access doors 315AL and 316AR.
(2)
Open the APU access doors 315AL, 316AR (Ref. TASK 52-41-00-010-001).
(3)
Set the LIGHT control switch 11LJ to the on position.
(4)
Place a drip pan under the oil cooler.
(5)
Remove the fan outlet duct assembly (Ref. TASK 49-52-41-000-002).
(6)
Remove the oil cooler exhaust duct (Ref. TASK 49-52-41-000-002).
4. Procedure
_________ Subtask 49-91-44-140-050
A. Cleaning of the Installed Oil Cooler
(1)
Prepare a cleaning fluid, 2 liters of CLEANING AGENTS (Material No. 11-013A) to 20 liters of demineralized or good quality drinking water.
(2)
Put the prepared cleaning fluid into a pressurized container with control valve.
(3)
Equip the pressurized container with a hose and adjustable spray nozzle.
(4)
Pressurize the container to 30 psi.
(5)
Adjust the nozzle to produce a fine spray.
(6)
Direct the spray nozzle into the top of the oil cooler matrix. Spray the oil cooler air passages with the cleaning fluid, maintain a minimum pressure of 20 psi (1.3789 bar).
(7)
Let the cleaning fluid dwell on the matrix for 10 to 15 minutes.
(8)
Flush the matrix with clean warm water.
(9)
Repeat the procedure until the matrix air passages are free of contamination.
(10)
Dry the air passages with compressed air at pressure not more than 60 psi (4.1368 bar).
(11)
Dry the exterior of the oil cooler with a clean, lint-free cloth.
(12)
Clean inside the cooler exhaust duct and the fan outlet duct, use a cloth dampened with the cleaning solution. Blow dry with compressed air.
(13)
Install the oil cooler exhaust duct (Ref. TASK 49-52-41-400-002).
(14)
Install the fan outlet duct assembly (Ref. TASK 49-52-41-400-002).
(15)
Make sure that the work area is clean and clear of tool(s) and other items.
(16)
Remove the drip pan from beneath the oil cooler.
(17)
Start the APU (Ref. TASK 49-00-00-860-005). If the APU starts and runs and no HOT shutdown occurs, return the APU to service.
(18)
If during the APU test a HOT shutdown occurs, do the procedure that follows.
Subtask 49-91-44-140-051
B. Cleaning of the Uninstalled Oil Cooler.
(1)
Remove the oil cooler (Ref. TASK 49-91-44-000-003).
(2)
Seal the oil inlet and outlet openings.
(3)
Use the procedures recommended by the supplier, clean the oil cooler and verify its cooling efficiency by rig test. Refer to APIC/CMM 49-91-03.
(4) Install the oil cooler (Ref. TASK 49-91-44-400-003).
________
5. Close-up
Subtask 49-91-44-410-056
A. Close Access
(1)
Install the oil cooler exhaust duct (Ref. TASK 49-52-41-400-002).
(2)
Install the fan outlet duct assembly (Ref. TASK 49-52-41-400-002).
(3)
Make sure that the work area is clean and clear of tool(s) and other items.
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