InterConnect has been designing and assembling aircraft electrical wiring harnesses now for over 23 years. During this period, we have seen a number of design mistakes dealing with electrical connectors.
The biggest mistake is that a customer begins to callout vendor part numbers instead of military connector part numbers on the Bill of Materials (BOM). The primary reason they do this is they are trying to save money. In most cases, Commercial-Off-The-Shelf (COTS) parts are less expensive than military part numbers. Unfortunately, in many cases they do not stay that way. Once a connector manufacturer realizes that their part number is listed on the BOM, they raise the prices since they are sole source. Connector manufacturers work hard to get companies who design aircraft electrical wiring harnesses to use their part numbers instead of military ones.
Besides pricing, a connector manufacturer can change their design and specification almost at will without coordinating the changes with the wiring harness design companies who callout their connector part numbers. These revisions or design changes can have adverse effects on what they were originally designed to be.
Military connector part numbers allow more competition in the aircraft industry. Additionally, to manufacture a military connector part number the manufacturer has to be qualified and listed on the Qualified Products List (QPL). QPL’s are well maintained and periodically tested as opposed to some COTS parts.
For more information about military parts (also called standard parts) versus COTS parts, please read InterConnect’s eBook “An Introductory Guide For Engineers Designing Aircraft Wiring Harnesses”.