Part Supersession Debacles

I have run into this problem so many times during my career it is not funny. You get this problem when you higher managers from rinky-dink schools like Keller and combine them with engineers willing to work for below market salaries. What is the problem? The misguided and ill-informed decision you can save money by using a single part supersession database for but current production assembly and field support.

Oh, believe me, I’ve seen all the spread sheets proving this to be the case! Those Keller grads, they know almost nothing about IT, but they can put together a spreadsheet proving anything in an afternoon. This is why spreadsheets aren’t tools, they are disasters waiting to happen. There is no cross checking as to what you left off in order to make the numbers work, let alone how realistic the numbers you presented are.

How do they manage to “prove” this obvious fallacy? It’s easy when you only have to convince other MBAs that know as little about IT and engineering as they do.

“Yesterday we were buying 140AMP alternators from AC Delco. Today we got a better deal from Bosch and they are drop in replacements.”

“Yesterday we bought grade 8 bolts from U.S. Fasteners, Inc. Today we are buying from China Steel world wide..”

The list goes on for a while with simple direct replacement parts. All of the MBAs in the room sit around wobble heading chanting “cut costs, cut costs.” and thus a debacle happens. Nobody in the room knows enough about parts or the business to understand production line REPLACED_BY is not field service REPLACE_WITH.

Let’s take a good example. There are thousands of these examples, but let’s take an easy to understand one. Say, back in the day, your company was buying truck seats, both driver and passenger from Duraform prior to them being purchased by Sears. All Duraform seats used the same bolt pattern to mount to the cab floor and the same hose size for air ride connection. Let’s assign the part number DURA-DRV-001 to the cheapest of the foam seats like you would find in a low end economy car. A serviceable seat for short drives, but definitely a 4-hour seat at best. (After 4 hours you have to take a long break walking around and stretching.) All of the dealer sales reps and parts counter people know that any DURA-DRV-nnn seat can be replaced with any other, as long as you aren’t picky about color.

Now, time goes by and Duraform gets sold. The new owners do not wish to honor the contract price, so, your company switches to Fred’s seat company. A shiny new series of part numbers gets entered into the database FRED-DRV-nnn, orders get placed, and the part supercession database has the old DURA-DRV numbers flagged as REPLACED_BY FRED-DRV.

All things beautiful, right?


What has been left out of this story is two critical pieces of information…much like they would be left off a spreadsheet. The Duraform seats had a 5-bolt pentagon mounting pattern and Fred’s seats have a 6-bolt star pattern. An engineering change gets scheduled for farther up the line and on that date the drill pattern changes for driver and passenger seat. Of course, you still have some of the old seats, so, for a brief time you have an adapter plate kit made, DURA-FRED-A-KIT. Problem is, this kit is made in such a way as to allow a Duraform seat to mount to a Fred blot pattern so you can use up the last of your parts inventory.

Five years go by. That cheap cloth cover and that cheap foam on the bottom end seat hit the end of their life cycle as far as the truck owner is concerned. They walk into the dealer with their VIN and say, “I want a new seat.” Ah, the fun starts. First they get shipped a Fred brand seat because that is what supercession calls for. When that doesn’t mount someone remembers the temporary adapter kit and special orders one of those. Weeks later when the kit arrives, they find it goes the wrong way. In desperation they fish around on the back of the seat for a brand and part number only to find that part numbers is nowhere to be found in the system.

In a screaming fit of frustration, the owner calls a third party vendor who happens to have a grizzled old parts veteran working for them. That veteran tells them Duraform was purchased by Sears and renamed Sears Elite. The owner purchases a Sears Elite seat from the grizzled veteran and is pleasantly shocked when the bolt pattern is a perfect match. Not only did they buy a “seat”, but they bought the top of the line $1200+ 800 way adjustable hug you with comfort from all angles ventilated leather seat, not the $200 utilitarian gotta hate waking up every day stock seat that came in the truck.

Yes, I’ve changed a few names, but, this is not a unique or special case. Countless other people have went through countless other problems all spawning from the same root problem. Field service needs a REPLACE_WITH database, but current production needs a REPLACED_BY database with scheduled replacement dates. Field service is only concerned with DROP IN replacements and adapter kits when a drop in simply isn’t made anymore. Production is concerned with what is coming down the line tomorrow.


Roland Hughes started his IT career in the early 1980s. He quickly became a consultant and president of Logikal Solutions, a software consulting firm specializing in OpenVMS application and C++/Qt touchscreen/embedded Linux development. Early in his career he became involved in what is now called cross platform development. Given the dearth of useful books on the subject he ventured into the world of professional author in 1995 writing the first of the "Zinc It!" book series for John Gordon Burke Publisher, Inc. A decade later he released a massive (nearly 800 pages) tome "The Minimum You Need to Know to Be an OpenVMS Application Developer" which tried to encapsulate the essential skills gained over what was nearly a 20 year career at that point. From there "The Minimum You Need to Know" book series was born. Three years later he wrote his first novel "Infinite Exposure" which got much notice from people involved in the banking and financial security worlds. Some of the attacks predicted in that book have since come to pass. While it was not originally intended to be a trilogy, it became the first book of "The Earth That Was" trilogy: Infinite Exposure Lesedi - The Greatest Lie Ever Told John Smith - Last Known Survivor of the Microsoft Wars When he is not consulting Roland Hughes posts about technology and sometimes politics on his blog. He also has regularly scheduled Sunday posts appearing on the Interesting Authors blog.