4. Install Sump Drain Assembly (Fig. 401)
A. Install two new O-rings, lightly lubricated with fuel, on drain assembly.
B. Guide drain assembly up through hole in drain well structure and insert end into upper housing.
C. Rotate drain assembly until lockpin slides into slot. Turn drain assembly counterclockwise until pin engages detent.
CAUTION: USE CARE WHEN ENGAGING DRAIN ASSEMBLY IN UPPER HOUSING TO AVOID BENDING OR SPREADING LOCKING DETENT EARS.
D. Install retaining plate on lower housing with four bolts and washers.
E. Align holes and secure retaining plate to drain well structure with two bolts and washers.
F. Actuate sump drain to open and closed position to ensure freedom of operation without binding.
NOTE: Fuel will drain from open drain assembly if tank contains fuel. Have suitable container ready to catch drainage.
G. Close sump drain access door.
H. Attach drain assembly bonding jumper to airplane structure.
I. Check electrical bond between sump drain and airplane structure per 20-22-01 I/C. Resistance shall not exceed 0.010 ohm.
J. Close air conditioning bay access door (Ref Chapter 21, Air Conditioning).
5. Remove Sump Drain Valve (Fig. 401)
A. Defuel and purge fuel tank (Ref 28-23-0, 28-10-0 MP).
WARNING: EXPLOSIVE AND TOXIC DANGERS OF VAPORS IN VICINITY OF FUEL TANKS WHICH HAVE CONTAINED FUEL ARE OF SUCH POTENCY THAT SEVERAL PRECAUTIONS MUST BE FOLLOWED BY PERSONNEL BEFORE ENTERING ANY WETTED OR DRY TANK FOR MAINTENANCE PURPOSES.
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28-11-41 Page 402 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Oct 20/84
587 Center Tank Sump Drain Assembly and Drain Valve Installation
Oct 20/84 Figure 401 28-11-41
Page 403
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
B. Gain access to bay No. 2 of integral center tank.
(1)
Ensure that rubber protectors are placed around access panel opening.
(2)
Remove shoes and put on a pair of tank boot socks just prior to entering tank. Do not allow socks to pick up any metal shavings or dirt from ladder or aerostand.
(3)
Enter fuel tank using properly protected lights.
WARNING: USE ONLY EXPLOSIONPROOF SHIELDED LIGHTS IN AND AROUND OPEN FUEL TANK.
(4)
Mopup residual fuel before working in tank.
(5)
Install rubber protectors in spanwise beam access hole.
C. Hold valve in place against spring tension while removing two sets of nuts, washers, and bolts, and remove sump drain valve.
D. Wipe valve seat clean, on upper housing, and check to ensure that sealing surface is in good condition.
6. Install Sump Drain Valve (Fig. 401)
A. Hold valve in place against spring tension and install two sets of bolts, washers, and nuts. Ensure that valve centers in seat correctly and that flapper action is unrestricted.
B. Remove all tools and equipment from bay and tank. Remove rubber protectors from access openings.
C. Install access panel (Ref 28-11-31, Removal/Installation).
D. Remove drain assembly (refer to step 3), fill tank with fuel, and check to ensure no leakage at outlet of upper housing.
CAUTION: HAVE SUITABLE CONTAINER READY TO CATCH ANY LEAKING FUEL.
E. Install drain assembly per step 4.
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28-11-41 Page 404 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 15/81
WING ROOT RIB ACCESS DOOR - REMOVAL/INSTALLATION
1. Prepare to Remove Wing Root Rib Access Door
A. Gain access to access door.
(1)
Airplanes with one or two cells in center tank:
(a)
Remove center tank access panel (Ref 28-12-21).
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