Installation of wires

I can not understand why 12 contact pins are used for installation of 12 pieces of wires whereas there are 24 termination points for 12 pieces of wires.
     
     
  

 

Probably the pins listed are for installation into the rack and the plugs will come with their contacts.

12 wires total. The pins called out are "only" for the plug on the right.

The other side of the wire group goes to different type plugs (which might have different pins).

Those pins must be identified in the Standard Wiring Practices Manual.

I see three jacks and the left and one plug. I know they don't use the same pins.

They could be male or female. Larger or smaller diameter.....

This post:  Pins/Splices/Terminals     Might help you out.


Direct Link:  rotate.aero/images/Basics/Tools_Pins_Sockets_Term.pdf


 

Do you mean operator should indent for additional 12 pins which are identified per SWPM in addition to 12 pins which are identified in the service bulletin?

You have 12 wires with two ends each... 12 more pins are required. I don't know if that's Boeing's job or the individual carrier, but they have to be there to complete the job.

I can not see where 19 plugs are used in the diagram.

Those are plastic sealing plugs to keep liquids out. They are installed at the rear of the plug in the pins slots that are not used.
  
     
 

So there should be one sealing plug for each contact pin so that 24 sealing plug should be fitted instead of 19 plugs

Sealing plugs don't really do much inside the pressure vessel. Especially, up front in the electronics compartment where there should be little to no water or hydraulic fluid.

We plug the holes that don't have wires, but they aren't needed for safe operation of an aircraft.

If I change a plug with ten unused pins, but they only supplied five plastic plugs.... I'll install what I've got and move on.