I recently discussed the necessity of keeping and having good records and data so that troubleshooting and problem-solving in the future could be performed. I had no idea that these ideas would come home to roost so quickly! I spent the last couple of days on the tarmac helping the US Forest Service and the Air National Guard fix one of their fire-fighting air tankers. It really drove home how important good information is to quality engineering.
About ten years ago Solutions Cubed completed controller for a modular fire-fighting system that would fit into a C-130 airplane. The client delivered the products to the US Forest Service, but then went out of business. The Forest Service has been maintaining the units for the last couple of years with no vendor support. Unfortunately, when the vendor went out of business, the Forest Service also lost all access to the schematics, complete wiring diagrams, parts lists, etc. Needless to say, this makes maintenance difficult. Recently they found a problem in the electrical system that they could not troubleshoot on their own and were able to find the Solutions Cubed website and contact us for help.
Four of us (a US Forest Service engineer, two mechanics, and I) spent a day tracing the problem and found the culprit – a shorted potentiometer. We were also able to reconstruct how it shorted (someone pressure washed it while it was powered!). That evening, they replaced the pot (on an airplane, nothing is replaced fast – there is too much at stake if something is messed up). The next morning we were able to test the fix and everything was back up to snuff. Another couple of hours of functional tests and the plane was cleared to fly. This is great, because this particular airplane is being used to fight the Chips, Reading, Ponderosa, Rush, and other fires all around where Solutions Cubed is located. So there is some self-interest in getting this fixed!
It is great that we were able to fix the problem, but it would have been much easier to diagnose if we had the correct documents. Below is video of the system operating on the ground.