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NOTE: The compressor air inlet must not be sprayed with preservative oil at any time.
(a)  
Install and secure all APU access panels.

(b)  
Apply protective coating of Turco Alumifilm or Spraylat ZR-5852 (preferred) or Spraylat TR 5157-1 (alternate) on metal surfaces to be masked around air inlet, exhaust outlet and cooling air inlet in access door.

(c)  
Mask off APU air inlet, exhaust outlet, and cooling air outlet in access door with approved polyethylene sheeting and masking tape No. 481 or equivalent.

(d)  
Ensure APU master control switch and battery switch are in OFF position.

(27)
Preservation Runs (to be performed on day 90 and at 30-day intervals for a maximum of 180 days)

(a)  
Remove all masking on APU air inlet; exhaust outlet and cooling air outlet.

(b)  
Fill oil tank to FULL mark on dipstick.

(c)  
Close following circuit breakers on panel P6:
1) APU CONT

(d)  
Place APU master control switch and battery switch to ON position.

(e)  
Position APU master control switch to START and release. Switch will return to ON and motoring will begin after air inlet door and APU fuel valve have opened. After 90 seconds, motoring is automatically terminated. Repeat cycle 3 times to achieve at least 3 minutes of motoring.

(f)  
Drain oil from tank and replace drain plug.

(g)  
Open APU control circuit breaker on panel P6.

(h)  
Place APU master control switch and battery switch to OFF position.

(i)  
Install masking on air inlet, exhaust outlet, and cooling air outlet per par. 5.D.(26).

(28)
On day 181, APU preservation may be renewed for an additional 180 days by performing steps 5.D.(1) thru 5.D.(27)(i).

(29)
On day 361, APU's still inactive must be placed in service or removed from installation.

May 01/03  49-11-0 Page 210C/210D BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

6.  Purge APU Fuel System
A.  General
(1)  APU fuel system purging is divided into two groups, low pressure and high pressure purging. In either group, use of ac boost pump is required.
(a)  
Low pressure purging ensures fuel to be present at APU low-pressure fuel filter.

(b)  
High pressure purging ensures fuel to be present at the atomizer. To ensure fuel being available at the atomizer, motoring APU is required.

B.  Equipment and Materials
(1)  
Container - 2-gallon minimum capacity

(2) 
 Fuel hose

NOTE:  Fabricate fuel hose to reach container and mate with fitting on end of high-pressure fuel line disconnected from fuel atomizer.
C.  Low Pressure Fuel Line Purging
(1)  
Prepare to operate boost pump.

(a)  
Position BATTERY SWITCH to OFF and placard.

(b)  
Verify all fuel system boost pump switches are OFF.

(c)
Open APU compartment access door latches and open access door. Install door support rods.

(d)  
Support shroud, open shroud latches and remove shroud.

CAUTION:  EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.

(e)  
Manually open APU fuel shutoff valve at left rear wing spar, accessible at left main wheel well area.

(2)  
Purge low-pressure fuel line.

(a)  
Provide airplane with external power.

NOTE:  No. 1 tank boost pump requires ac power.

(b)  
Position No. 1 tank forward boost pump switch to ON.

NOTE:  If you must use the fuel boost pumps in the center tank, you must have a maintenance person or observer in the flight compartment to continuously monitor the LOW PRESSURE lights.  Turn the applicable fuel boost pump to the OFF position if the LOW PRESSURE light for the center tank stays on.
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(c)  
Loosen fuel line at low-pressure inlet (inlet side of low-pressure fuel filter) just enough to allow trapped air to escape.

(d)  
Catch dripping fuel in container.

(e)  
Tighten fuel line fitting when all air has been expelled.

(f)  
Position APU master switch to OFF.

(g)  
Position No. 1 tank forward boost pump switch to OFF.

(h)  
Manually close APU fuel shutoff valve at left rear wing spar.
　
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