This one is not quite along the same lines, but nonetheless a very
interesting item with potential deadly consequences. I work for a very
large aircraft manufacturer. In the process of building widebody airplanes,
the front and back body sections are joined to the center body and wing
section in a huge jig called final body join. After the sections are slid
together and aligned, there are a number of titanium temporary fasteners
that are installed to keep anything from moving. It's called "pinning"
Sixteen or so pins, I think.
So, early one morning after an airplane had been joined and pinned,
someone (well, the story seems to change slightly depending on who you hear
it from!) decided to jack the tail up six inches. Okay, so here's a rather
long airplane and the leverage exerted from about a hundred feet back on
three varied aluminum alloy layers, none more than a quarter of an inch
thick is pretty incredible. Can you imagine what happened next?
Up until this point, I had never seen a bent titanium fastener of this
type. Not just bent once, but dog-legged. Well, I'm told by those that
were walking around at the time that it sounded like popcorn or .22 rounds
going off, and these fasteners came flying out a rather great velocities.
People were diving all over the place to avoid something they had no clue
about. The skin material next to the holes was swaged/squashed up and/or
pulled "long" and when the strain was too much, the "nuts" on the pins gave
way, letting these things fly. The damage was so extensive they went ahead
and finished building the plane, stuck together with a few hundred temporary
bolts, then when done down the line, they pulled it aside and replaced
several million dollars worth of skin panels and underlying structure.
Pretty incredible what it looked like, being able to see all the way through
the plane to the other side, with nothing but the skeleton seeming to hold
| This was at my dad's work. They were moving an F-16 with a crane
| when there was a loud pop. Naturally, they stopped the crane, and
| unnaturally a bunch of people started walking around the plane to figure
| out what had popped. Including roaming around beneath it.
| Nobody found anything, so everyone got back and they started moving
| the whole thing again. A second later, popohshitwham! F16 on the floor
| with a few million in damage to it.
| Turns out when they recently overhauled the cranes there someone
| ordered a wrong bolt--was off by one line in the chart. So the
| connection between the hook and the pulleys wasn't strong enough and
| gave way.
| They're extremely lucky the thing didn't fall on those idiots under
| it. At that time it was down to one half-sheared bolt holding up the
| whole weight.
| B.B. --I am not a goat! thegoat4 at airmail dot net
| http://web2.airmail.net/thegoat4 /