Not the headline Boeing suits were hoping for.
From the article:
“The bolts needed to keep the plug in place were missing,”
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They were dam lucky the door blew out when it did. At 36,000 feet it could have been a different outcome.
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They should worry less about the stock crashing and more about the planes crashing
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But maybe the headline that help Airbus win market dominance?
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Sounds like they may be ISO 8999 not 9000 qualified.
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The Soviets used to be great at this sort of thing:
Fascinating study.
So now we have another great American corporation, killed and eaten by the finance types.
Earl
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“Hey!” These bolts will work on the 69 Chevelle I’m restoring."
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More here:
Earl
Shit, I just flew on one one those planes cross country. Don’t take the super economy seats, they suck…And don’t sit by the faux door. The Embreair has bigger standard seats from Denver to Spokane. Saw massive land based wind farms on the way.
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With the airlines continuing to shrink seats and legroom coupled with the obesity pandemic, it’s worth the extra money to go first class and avoid the sardine section. The last straw for me was a ‘roid addled muscle bound freak next to me in economy who displayed his man-spread for the entire flight.
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According to one report the Alaska plane prior to the unused hatch blowing off had been restricted to no over water flights due to having a few loss of pressurization alarms . What was the thinking there? Did they want the bodies easier to find?
Boeing used to be a great company prior to their merger. Now? I prefer not to fly on any of their newer 737 iterations. The FAA is a victim of regulatory capture so they are no longer trusted. If only the NTSB had regulatory authority…
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More disturbing to me is the design of the panel. It used to be pressurization would “press” doors closed against the frame of the aircraft. Apparently, this one was not designed/built this way. WTF they even put a “panel” in the fuselage, anyhow? FUBAR.
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I read that in some configurations it’s the location of a sally port or extra door.
If the airline configures with the highest density seating, the regs mandate a wide emergency exit aisle and door at that location. Alaska uses lower density seating, so the door is not required. Instead of just including a door and aisle there anyway, somebody (Alaska, Boeing, or both) decided to eliminate the aisle and replace the door with a removable panel. My guess, and it’s just a guess, is they did this to save the weight of the door. This lets Boeing make one standard fuselage that can be configured with either one or two emergency exits. All very efficient and win-win except …
… as seasmaster noted, they decided it was ok to put all the pressurization stress on the fasteners instead of the normal “tapered plug” fixing of doors. And it appears that the stress calculation had narrowed the margin of safety (fewer screws, less material cost, less assembly steps) sufficiently that the door blew out at 16,000 feet (which is not all that high) when just four fasteners were omitted.
I would love to see the design analysis of that plug. My guess (and it’s again just a guess) is that we’ll see yet another case of computer-assisted design enabling “efficiencies” that in the old days would have been precluded by some experienced engineer thinking “four fasteners should be OK, if that thing blows out it’s catastrophic, let’s use eight.” Over the course of my career I’ve seen the elimination of “over-engineering” evolve to the point where we’re now eliminating basic engineering.
Earl
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From what I’ve seen, the design was working fine-- it was the fasteners that hold the plug in the locked position that were not installed or failed or rattled loose. This plug installed from the outside and locked into place just like every other door on the plane, so clearly it’s a design that works. I’m pretty sure this will be a case of checklists not followed and quality assurance falling to crap. Fortunately, nobody had to die to learn (re-learn) this lesson. Plus, who knew a cellphone could survive a fall from 16,000 feet?
Yeah, now that I think about it, you’re right. The plug doesn’t replace the door, it replaces the door frame. So taper is irrelevant.
Now the question is, how much redundancy is there in the door frame design?
Earl
Well, if you want to play airframe designer, here’s the NTSB diagram of how the plug is attached:
Cheers,
Earl
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Unfortunately one of my most used expressions in todays world, which can be used in a vast amount of situations such as the above and in my case most often working on the water is, in reference to the labor pool……
IT ALL COMES DOWN TO THE LOWEST COMMON DENOMINATOR.
AKA - The weakest link
When the FAA rubber stamps inspections it is called regulatory capture.