The aircraft had come to the hanger for planned maintenance, on this aircraft there was a fire detection loop problem that needed to be fixed. My colleagues started on that job and I started on another job that was in the technical logbook.
A reed switch had been found to be faulty, our colleagues at the line maintenance had troubleshooted the defect and they had ordered a new switch.
This switch turns the power on for the fuelling system of the aircraft when u open the fuelling panel, if this switch doesn't work there is a manual overide that needs to be pressed in order to power the fuelling system but ofcourse we want the switch working.

So I get started by getting the right tools for the job and setting up the steps and the parts needed.

This is the fuelling control panel.

The power should be on when the panel is opened but it doesn't work.

This is the switch that causes the defect, a reed switch is a magnetically operated switch. the target that moves with the door is a magnet, as soon as this magnet comes close enough to the reed switch the contact inside the switch closes completing a circuit and power should be applied to the fuelling control panel.

Here's the new switch, straight from the box.

As i take the old switch out, it's evident that it's been on the aircraft for quite some time. One of the screws is totally corroded.

Once again, I have little or no access to get the wires out.

So instead of crimping new pins on the wire and insert them into a connector I decide to splice the wires onto the original wiring.
These are some wire splices that I can choose from.

In this case I use awg 16-18 waterproof splices.

I make myself some space.

I temporarilly splice the new switch.

And then I splice the new switch onto the wires of the old switch.

With these temporary splices I can pull the new wiring through the P-clips without disconnecting them. This saves me a good couple of hours work.

Then I pull the wiring through the P-clips and cut out the wiring that I don't need.

I put the shrinksleeves over the wire, do this BEFORE u crimp the splices into the wire, it took me quite some trial and error before this was common practise.

Then we can crimp the wire splices onto the wires.

Then I put the shrinksleeves over the wire splices and crimp the sleeves with a heat gun making the wire repair watertight.

The wires are now spliced, I put them back into the wire loom and tie the loom back together with tie laces. I reconnect the connectors to their receptacle's and install the new reed switch with new screws (the old ones were corroded).

Proper tie lacing makes a wire loom rigid and easily routeable.

As u can see, the power is back onto the fueling control panel, the new switch works fine.

I close off by testing the panel and the systems that were affected by the connectors that had been disconnected. This job is complete and I go and see if I can help out at the fire loop problem that my colleagues are trying to fix (turns out that became quite interesting too, too bad I didn't take pictures of that job).

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