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4 Critical Items to Include When Designing Aircraft Modification Kits



Now that US Aerospace and Defense manufacturers are extending the life of more and more older aircraft, fixed-wing and helicopter modification kits are becoming more and more prevalent. In the last 26 years InterConnect Wiring has assembled thousands of aircraft modification kits (AKA mod kits, loose wiring assemblies, or LWA’s) for a wide variety of OEM’s (Original Equipment Manufacturers) such as Lockheed Martin, Boeing, and L-3, as well as directly for the US Department of Defense (DOD). We have also provided kits for non-defense-related aircraft as well. Currently there is no aircraft modification kit standard throughout the aerospace industry, thus the design can vary widely. Provided below is a list of important things to remember when designing aircraft modification kits.


  • Include each part number on the Bill of Materials (BOM) as well any corresponding superseded part number.


Over the years, many military part numbers have been superseded by new part numbers.  This is also true for non-standard parts and commercial aerospace parts. Since aircraft mods are typically done on older aircraft, most of the part numbers listed in tech manuals are the older, superseded part numbers.  Because of these older tech manuals, it is important that engineers list the superseded part number as well as the new part number in the kit contents list. It also helps the technicians who install the kits if the National Stock Number (NSN) is listed with the part numbers (just in case the technician needs to order more spare parts).


  • Add extra “floor stock” parts.


Many aircraft maintainers and technicians do not have extra floor stock of small, inexpensive parts.  For this reason, the kit contents designer should add a few extra parts just in case some of the parts get lost or the kit manufacturer miscounts the quantity.  As an example, a military electrical kit might require four (4) MS27488-20-2 filler plugs, and three (3) M39029/4-110 contacts. Instead of listing the actual quantity needed, the designer may want to list six (6) MS27488-20-2 filler plugs, and five (5) M39029/4-110 contacts.


  • Add extra wire lengths.


One of the most common mistakes when designing electrical aircraft modification kits is wire lengths.  This is especially true for older aircraft where there is no CAD, 3D drawing. There is nothing more frustrating to kit installers than to run new wire for a mod and come up short.  Wire is relatively inexpensive so extra wire does not add much cost to the mod kit. The table below shows InterConnect Wiring’s recommended extra lengths to add to each wire in a kit: 



  • Provide the TCTO and/or MWO.


Many aircraft mod kit designers do not provide the kit manufacturer with a copy of the technical installation document.  For the Air Force this document is called a Time Compliance Technical Order (TCTO) and for the Army it is called a Maintenance Work Order (MWO).  By failing to supply this document, the kit manufacturer cannot see the “big picture”. By not providing the technical document, the result may be a kit that does not exactly match the technical installation document.  This may cause confusion and mistakes when installing the kit.


  • Include all tooling requirements.


Many designers fail to consider the small disposable tools needed for aircraft mods.  This is especially true for contact insertion and removal tools. These tools are plastic and easily damaged.  Depending on the size of the kit and the number of contacts that a mod requires, many extra plastic insertion and removal tools should be included in the kit’s contents.  


InterConnect Wiring has designed many modification kits for its customers and knows what is important to include when designing aircraft kits or LWA’s. InterConnect has also manufactured approximately ¼ of a million kits over the past 26 years. That’s a lot of kits! If you need a loose wire assembly or kit designed and/or manufactured, please contact us at 817.377.WIRE (9473). 

Our License

We are the sole licensee of Lockheed Martin for F-16 electrical products. Through this agreement, we have access to Lockheed Martin’s F-16 engineering data, tooling and configuration control information. We also have a Technical Services agreement with Sikorsky for all of their aircraft. This agreement allows us to obtain their engineering data needed to rewire helicopters that Sikorsky manufactures.



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