(4)
If necessary, polish the fay surface area of the front spar at the mating surface of the flange on the bulkhead fitting (SOPM 20-30-02 or SWPM 20-20-00):
CAUTION: KEEP THE BARE METAL SURFACES EXPOSURE TIME TO LESS THAN FOUR HOURS. RUB THE BARE METAL SURFACE AREA AGAIN BEFORE YOU APPLY THE CONVERSION COATING IF EXPOSURE TIME IS MORE THAN FOUR HOURS. THE CONVERSION COATING WILL NOT ADHERE CORRECTLY TO A BARE METAL SURFACE THAT IS NOT CLEAN.
(a)
Use 320 grit or finer abrasive to remove the remaining anodic surface finish to make a clean and flat bare metal surface all the way around the hole for the bulkhead fitting (in and out of the tank).
NOTE: Remove the minimum quantity of material.
(b)
Make sure the anodic surface finish is less that 0.0001 inch (0.025 mm).
(c)
Polish and clean to a minimum of 0.0625 inch (1.59 mm) diameter more than the bulkhead fitting out of the tank on the front spar.
(d)
Polish and clean to a minimum of 0.0625 inch (1.59 mm) diameter more than the nut in the tank on the front spar.
501
28-22-142 Page 404 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. May 01/03
(5) Apply a conversion coating (Alodine 600, Type II, Class D) to the bare metal surfaces on the inner and outer surfaces of the wing front spar with a small, clean brush (SOPM 20-43-03).
NOTE: Alodine 600 gives a good electrical conductive coating. Some types of Alodine are not electrically conductive. Some types of Alodine create a powdery coating if they are used on the fuel tank paint finishes.
E. Install the Bulkhead Fitting
(1)
Install a new O-ring on the bulkhead fitting.
(2)
Align the bulkhead fitting with the hole in the front spar for the engine fuel feed line.
(3)
Install the nut on the bulkhead fitting.
(4)
Tighten the nut to a torque of 855-945 inch-pounds (96.6-106.8 Nm) (SOPM 20-50-00).
(5)
Measure the bonding resistance between the bulkhead fitting and the front spar
(SWPM 20-20-00).
WARNING: MAKE SURE YOU USE A EXPLOSION-SAFE BONDING METER TO DO A CHECK OF THE ELECTRICAL RESISTANCE (SWPM 20-20-00). AN OPEN FUEL TANK IS AN EXPLOSIVE VAPOR AREA.
(a) Make sure the electrical resistance is less than 0.0005 ohm.
(6)
From out of the fuel tank, install the gasket and four bolts and washers to attach the engine fuel feed line to the bulkhead fitting (SOPM 20-50-00).
(7)
From in the fuel tank, connect the engine fuel feed line to the bulkhead fitting.
(8)
Do a test of the engine fuel feed system for leaks (AMM 28-22-0/201).
NOTE: Refer to the Engine Fuel Feed Lines/Fittings Vacuum Test.
(9)
Apply a fillet seal of BMS 5-26, Type II (or BMS 5-45, Class B) sealant to these areas (SOPM 20-50-19):
(a)
Seal the joint between the outside diameter of the bulkhead fitting and the wing front spar. 1) Seal to a minimum 0.1875 inch (4.76 mm) diameter more than the nut in the fuel
tank on the other side of the front spar.
(b)
In the fuel tank, seal the threads on the engine fuel feed line and the nut threads.
1) The sealant must extend to the flat dimension of the nut and at least two threads of the bulkhead fitting.
(c)
Apply sealant to the joint between the outside diameter of the flange on the bulkhead fitting and the wing front spar, in and out of the fuel tank, the joints between the engine fuel feed lines and the bulkhead fittings and the surrounding areas. 1) Seal to a minimum 0.1875 inch (4.76 mm) diameter more than the bulkhead
fitting on the front spar.
501
May 01/03 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-22-142 Page 405
(10)
Clean the wing front spar area of all particles and dust caused by the fay surfacing process.
(11)
Apply BMS 10-20, Type II primer, as necessary, on the alodined bare metal at the forward and aft front spar surfaces (SOPM 20-41-02).
(12)
Apply BMS 10-60, Type I or Type II enamel finish where it is necessary, on the primer on the front spar surfaces (SOPM 20-44-03).
(13)
Do these steps to close the applicable fuel tank:
(a)
Remove all tools, all equipment and all unwanted material from the fuel tank.
(b)
Install the applicable left (right) fuel tank access panel 7205 (7405) you removed to get into the fuel tank (AMM 12-31-61/201, AMM 28-11-11/401).
(14)
Do these steps to do a final check for fuel leakage:
(a)
Refuel the applicable fuel tank until it is 75% full (AMM 12-11-01/301).
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：737 AMM 飞机维护手册 燃油 FUEL(146)
