Posts by 4mula1

40 years ago, classified Shuttle mission foreshadowed Challenger's fatal flaw

Both STS-51-C and the ill fated STS-51-L had Ellison Onizuka on board. Made me pause for a moment seeing his name connected to this flight.

A time when cabling was not so much 'structured' than 'survival of the fittest'

Several years ago at work a maintenance guy was working inside the electrical cabinet of a machine and learned that an accessory mounted to the machine didn't have it's power controlled by the disconnect switch on the main machine. The power had been shut off to the machine by said disconnect switch and while doing whatever work inside the cabinet he needed to do he managed to touch the long screwdriver he was using to one of the, unbeknownst to him, still live power leads to the accessory and ground. It was only 208V (and just one of the 3 phases) but it's not the voltage that kills, it's the current.

I was sitting in the office nearby at the time with my back to the production area but heard the loud BZRRT! and saw the flash of light on the wall. Two of us ran out to see if he was okay and he way on his back on the floor. When asked if he was okay he said "Well, I'm not dead since I'm talking to you."

I don't know if they ever wired the accessory to use the disconnect switch but from that point on everybody knew to double check similar machines for the same condition.