5. Preserve APU
A. General
(1) This section contains instructions for preserving the APU to protect against corrosion during inactive periods. Preservation by periodic operation of the APU (every 7 days) is the recommended action. An optional method of preserving the APU for longer periods of time or when preservation by periodic operation is discontinued is also acceptable.
B. Equipment and Materials
WARNING: PROLONGED CONTACT OF LUBRICATING OIL WITH SKIN CAN CAUSE DERMATITIS, STAIN CLOTHING AND SOFTEN PAINT. REMOVE SATURATED CLOTHING IMMEDIATELY AND THOROUGHLY WASH SKIN AFTER CONTACT. PAINTED SURFACES SHOULD BE CLEANED IMMEDIATELY AFTER CONTACT WITH OIL.
(1)
Mineral Oil -MIL-L-6081, Grade 1010 or 1005
(2)
Tape - 3M Company No. 481, Permacel P32, or equivalent
(3)
Non-adherent covering - Mylar Polyethylene or Polyvinyl Chloride or equivalent per BAC5034 Type II, Class I, Grade A
(4)
Turco Alumifilm, Spraylat ZR-5852 (preferred) or Spraylat TR 5157-1 (alternate)
C. Preservation by Periodic Operation
(1) On day 1 and at 7-day intervals thereafter, operate APU at no-load governed speed for a minimum of 5 minutes.
D. Preservation by Optional Method (To be performed when preservation by periodic operation is discontinued)
(1)
Start APU and operate at no-load governed speed for a minimum of 5 minutes, shut down APU and preserve while engine is hot.
(2)
Open the following circuit breakers on panel P6:
(a) APU CONT
(3)
Position BATTERY SWITCH and APU START SWITCH to OFF and placard that APU maintenance is “in work.”
(4)
Open APU shutoff valve at left rear wing spar, accessible at left main wheel well area. Gain access to Tank No. 1 and disconnect fuel feed line at check valve. Drain fuel from APU and reconnect line.
(5)
Open APU compartment access door latches and open door. Install door support rods.
(6)
Support lower shroud, open shroud latches, and remove shroud.
CAUTION: EXERCISE EXTREME CARE NOT TO DAMAGE SHROUD DRAIN LINES WHEN HANDLING SHROUD.
(7)
Disconnect electrical harness from ignition unit.
(8)
Disconnect engine fuel inlet hose from elbow on low-pressure fuel filter and drain hose. Reconnect hose.
(9)
Remove and discard low-pressure filter in the fuel inlet line between the shroud and fuel control.
(10)
Dip new fuel filter element in mineral oil and install with new packing.
(11)
Disconnect high-pressure fuel line from fuel atomizer and drain fuel into suitable container.
(12)
Fabricate a fuel hose and connect one end to the high-pressure line and place other end in 2-gallon container.
(13)
Disconnect fuel supply line at shroud inlet port and connect to APU line a fabricated hose at least 2.5 feet long.
(14)
Raise end of hose approximately 2 feet above shroud fuel inlet port and gravity feed mineral oil.
(15)
Close the following circuit breakers on panel P6:
(a) APU CONT
(16)
Place battery switch to ON position.
(17)
Position APU master control switch to START and release.
NOTE: APU master switch will return to ON: engine motoring will begin after air inlet door and APU fuel valve has opened. After 90 seconds of motoring, motoring is automatically terminated.
(18)
Position APU master control switch to OFF.
(19)
Repeat steps (17) and (18) until clear oil is seen from overboard drain line.
CAUTION: DO NOT EXCEED STARTER MOTOR DUTY CYCLE OF 4 MOTORING CYCLES IN A 30-MINUTE PERIOD.
(20)
Open following circuit breakers on panel P6:
(a) APU CONT
(21)
Remove and discard fuel control unit high-pressure fuel filter element. Reinstall empty filter housing and tag to install new filter when depreserving unit.
(22)
Remove drain hose from high-pressure fuel line and reconnect line to fuel atomizer.
(23)
Disconnect hose at shroud fuel inlet port and cap line with plug.
(24)
Install cap on fuel supply line at shroud.
(25)
Oil System Preservation (to be performed on or before day 61).
(a)
Remove oil tank drain plug and drain oil. Allow all oil to drain.
(b)
Remove and discard oil filter element and packing from oil pump assembly. Reinstall empty filter housing and tag to install new filter when depreserving.
(c)
Replace oil tank drain plug using new packing.
(26)
Unit Preservation (to be performed on or before day 61)
500
May 01/03 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 49-11-0 Page 210A
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