NOTE:  The liner is important to the safety of the float switch installation.  This is the last step where a person can make sure it is installed and document that fact.
(a)  Make sure the installation of the liner in the conduit is written in the maintenance records for the airplane.
(17)
Do these steps to install the drain port assembly:

(a)  
Put the float switch electrical cable into the hole in the drain port assembly.

(b)  
Slide the drain port assembly along the electrical cable to the front spar bulkhead union.

(c)  
Install the drain port on the front spar bulkhead union.

NOTE: Make sure the drain port shoulder is seated in the formed liner.

(d)  
Tighten the drain port (35) to a torque of 9.0-11.0 inch-pounds (1-1.2 Nm).

(e)  
Install lockwire from the drain port (35) to the bolt (33).

(f)  
Install lockwire from the conduit mounting nut (36) to the bolt (33).

(18)
Do these steps to splice the float switch electrical cable to the airplane wire harness:

(a)  
Cut the electrical cable as necessary to permit a wire splice to the airplane wire harness with less than 1.0 inch (25.4 mm) of excess wire.

(b)  
Splice the float switch electrical cable to the airplane wire harness with the applicable crimp tool (SWPM 20-30-12).

(c)  
Put two layers of electrical splice tape over the splice to prevent damage from water and fuel.

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8.  Put the Airplane Back to Its Usual Condition
A.  Install the access panels that you removed to get access to the fuel tank.
(1)  
For tank No.1 or No. 2, refer to AMM 28-11-11/401.

(2)  
Install the slat access panel (if applicable).

(3)  
For the integral center tank (if applicable), refer to AMM 28-11-31/401.

(4)  
For the center tank with removable bladder cells (if applicable), refer to  AMM 28-12-21/401 and AMM 28-12-31/401.

(5)  
For the auxiliary tank (if applicable), refer to AMM 28-14-11/401.

B.  Fill the tank with fuel and do a check for fueling switch cutoff (AMM 28-21-0/501).
C.  With fuel in the tank, do a check for fuel leakage at the conduit bulkhead fitting; no leakage is permitted (AMM 28-21-71/601).
NOTE:  To do a leak check of the conduit for the center tank float switch, make sure the center tank and tank No. 2 are filled with fuel.
D.  Remove the leading edge flap locks (AMM 27-81-0/201).
WARNING:  LEADING EDGE FLAP CAN MOVE QUICKLY AND CAUSE SERIOUS INJURY TO PERSONS.
E.  If installed, remove the tank No. 2 boost pump bypass valve lock and replace the access plug in the wing lower skin.
505 
May 01/03  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  28-21-71 Page 427 

FUELING FLOAT SWITCH - INSPECTION/CHECK
1.  General
A.  Electrical wiring to the float switches is enclosed in the conduit with fuel-tight connections. Wiring splices are located close to the respective conduit bulkhead fittings at the wing front spar.
B.  This procedure gives the instructions to inspect the fueling float switch conduit located at the wing front spar station 494, external to the fuel tank, inspect the center tank fueling float switch wiring, and inspect the center tank float switch electrical conduit.
2.  AIRPLANES PRE-SL 28-42; Wing Tank Float Switch Inspection/Check
A.  Equipment and Materials
(1)  
Leading Edge Flap Actuator Locks - F80048-89 (Preferred), F80048-90 (Preferred), F80048-84 (Alternate), and F80048-36 (Alternate)

(2)  
Flexible plastic tubing 1/4 inch or less outside diameter and vacuum source such as syringe

B.  Prepare for Inspection
(1)  
Extend the flaps and install leading edge flap locks (AMM 27-81-0/201).

WARNING:  FLAPS ARE FAST ACTING AND CAN CAUSE SERIOUS INJURY TO PERSONNEL.

(2)  
Check that the fueling shutoff valves at the fueling station are closed.

(3)  
Disconnect the external electrical power, if connected.

C.  Wing Tank Float Switch Inspection
(1)  
Make sure wing tanks are full of fuel.

(2)  
Get access to the wing tank float switch wires at the wing front spar station 494, external to the fuel tank.

(a)  Remove slat access panel No. 6223/6523.

(3)  
Visually inspect the bulkhead union for signs of fuel leakage.

(4)  
　
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