(a)
Turn the bulkhead union (20) to mate with the retainer (22) as positioned for installation.
(b)
Tighten the conduit mounting nut (18) to a torque of 342-378 inch-pounds (38.6-42.7 Nm).
(8)
Install the retainer (22) with the bolts (16), washers (24, 26, 27), packings (25), and nuts (14).
(9)
Inside the tank, put the center of the float switch bonding lug hole at a location that causes the minimum torsional load of the switch cable.
(10)
Do these steps to tighten the parts that attach the float switch:
(a)
Tighten the float switch mounting nut (3) to a torque of 266-294 inch-pounds (30-33.2 Nm).
(b)
Tighten the float switch conduit captive nut (8) to a torque of 266-294 inch-pounds (30-33.2 Nm).
(c)
Tighten the conduit join captive nut (11) to a torque of 275-280 inch-pounds (31.1-31.6 Nm).
(d)
Tighten the union conduit captive nut (19) to a torque of 266-294 inch-pounds (30-33.2 Nm).
(e)
Loosen the float switch mounting nut (3) sufficiently to relax the torque temporarily.
(f)
Loosen the union union conduit captive nut (19) sufficiently to relax the torque temporarily.
(g)
Loosen the float switch conduit captive nut (8) sufficiently to relax the torque temporarily.
(h)
Loose the conduit join captive nut (11) sufficiently to relax the torque temporarily.
(i)
The final torque for each of these nuts must be witnessed and written in the maintenance records for the airplane: 1) Tighten the float switch mounting nut (3) to a final torque of
266-294 inch-pounds (30-33.2 Nm). 2) Tighten the conduit captive nut for the float switch to a final torque of 266-294 inch-pounds (30-33.2 Nm). 3) Tighten the union conduit captive nut (19) to a final torque of 266-294 inch-pounds (30-33.2 Nm). 4) Tighten the conduit join captive nut (11) to a final torque of 275-280 inch-pounds (31.1-31.6 Nm).
(j)
Make sure the final torque for each of these nuts is written in the maintenance records.
(11)
Out of the fuel tank, install the coupling ring (17) on the end of the bulkhead union (20).
(a)
Make sure the grommet end of the coupling ring (17) is firmly installed inside the clear liner.
(b)
Tighten the coupling ring (17) to a torque of 32-38 inch-pounds (3.6-4.3 Nm).
(12)
Do these steps to install the bonding jumpers (SWPM 20-20-00):
(a)
Install the bonding jumper (2) on the ground lug for the float switch.
1) Choose a jumper whose length will prevent too much loose bonding jumper after the bonding jumper is installed.
(b)
Install the other end of the bonding jumper (2) on the ground lug on the switch bracket.
(c)
Install the bonding jumper (4) on the ground lug on the switch support bracket.
(d)
Install the other end of the bonding jumper (4) on the conduit with the clamp, screw, washer and nut. 1) Adjust the jumper lug position as necessary to remove the loose part of the
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May 01/03 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-21-71 Page 421
bonding jumper.
(13)
Measure the resistance from the float switch ground lug to the primary structure of the wing rib (SWPM 20-20-00).
(a) Make sure the resistance is less than 0.01 ohm.
(14)
At the conduit join, measure the resistance from the bonding jumper terminal to the conduit.
(a) Make sure the resistance is less than 0.0015 ohm.
(15)
Measure the resistance between the conduit and the primary structure of the wing rib.
(a) Make sure the resistance is less than 0.010 ohm.
(16)
Install lockwire in these locations:
(a)
Install lockwire from the bulkhead conduit captive nut (15) to the nut (14) (AMM 20-10-191/401).
(b)
Install lockwire from the mounting nut (3) for the float switch to the float switch bracket (AMM 20-10-191/401).
(c)
Install lockwire from the conduit captive nut (8) to the mounting nut (3) (AMM 20-10-191/401).
(d)
Out of the tank, install lockwire from the conduit mounting nut (18) to the bolt (16) (AMM 20-10-191/401).
(e)
Install the lockwire from the coupling ring (17) to the bolt (16) (AMM 20-10-191/401).
(17)
Do these steps to splice the float switch electrical cable to the airplane wire harness:
(a)
Cut the float switch electrical cable as necessary to permit a wire splice to the airplane wire harness without leaving more than 1.0 inch (25.4 mm) of excess wire.
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