Frustration

I've been performing a software mod on an aircraft computer for about five months. These computers were designed in the 1990s and utilized a FLASH memory chip that is now obsolete and scarce. Honeywell released new software that would allow the computer to work with newer FLASH memory chips.

Performing the mod is simple. I power up the computer and install a PCMCIA card containing the new software. It loads automatically. As standard procedure, I reload the main database and application software too.

Since December, I've had three computers fail Bank 5 after installing this software. Computer memory is divided into seven different banks, and Bank 5 would test as blank. I thought I was seeing a hardware failure - not uncommon after an upload - so I replaced the address and control circuits on both the memory board and its interface on the main board. Nothing helped.

I talked with our Honeywell rep about it. He emailed an engineer at their repair facility, and the engineer suggested a simple fix that I hadn't considered. He suggested installing the big database on a fresh PCMCIA card to try on the computers. It worked!

Now I'm trying to figure out why my other PCMCIA card would cause failures on just a few computers while loading flawlessly on others. Regardless, it's going in the trash, but I'm curious as to why it would fail. I've read a bit about wear leveling in FLASH memory, a scheme that extends the useful life of a chip by using an address map to prevent repeated read/write operations from causing failures. That's a possibility but if the engineer gets back to me with something definitive, I'll update this.

Regardless, I had three computers that had me mumbling to myself with frustration, but now they're all going away!

Panic Week! Day Two

It started out as a slow day. I arrived at work a little before 6AM. We heard that the FAA inspection team arrived at 6:45. No slackers, them.

Modified stationary panic is actually infectious. Our planner/acting supervisor was wandering around seemingly at random. The ESD/chemicals guy was practically vibrating. And the target for the day seemed to be air pressure.

Yes, air pressure. You know, we use compressed air to blow dust out of electronic units. And some of the manuals specify limits on the pressure. This may seem to be a minor deal, but when the feds come looking, it's important to see that our shop tools conform to manufacturers specs.

I went looking through the manuals for the ground prox warning computer. It didn't have a spec for the air pressure, but I found this gem in the modifications section:

"A microcircuit with a specific die version from a specific manufacturer can possibly have a
single event latchup when hit by a neutron. This modification gives the instructions to
examine and replace these microcircuits as necessary."

That explains so much! I had a computer that started singing "Danke Shoen" over and over. It probably took a hit from a Wayne Neutron, but regardless, it's out in Vegas now doing a lounge act. It left a trail of sequins leading out the door.

(Gosh, that was a long way to go for a joke! Still, it was a better than the zombie jokes.)