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Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

bbc.com

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Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#21

Post by somat »

rabidonrails wrote: post #9
CGMthrowaway wrote: post #8

The headline is missing an important bit. Boeing knew of the flaw, and sent a letter to airlines about it. In 2011.

Well yes but Boeing also said it "would not result in a safety of flight condition." There's a lot of gray going on here.

I am wondering what the exact fail mode here is.

Because my naive conclusion after looking at the part in question is exactly the same "would not result in a safety of flight condition." if the bearing cracked at the point in question it is going nowhere, the bearing is still captive in its housing. hell it looks like it could have been designed as two pieces and it would work the same. the large bolt is what is holding the engine on.

The best I can come up with is that a split bearing causes increased wear on the mounting bracket and nobody noticed for a long time.

Anyhow, here is the ntsb update in question https://www.ntsb.gov/investigations/Documents/DCA26MA024%20I...

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#22

Post by jacquesm »

somat wrote: post #21
rabidonrails wrote: post #9

Earlier quoted context omitted.

Well yes but Boeing also said it "would not result in a safety of flight condition." There's a lot of gray going on here.

I am wondering what the exact fail mode here is. Because my naive conclusion after looking at the part in question is exactly the same "would not result in a safety of flight condition." if the bearing cracked at the point in question it is going nowhere, the bearing is still captive in its housing. hell it looks like it could have been designed as two pieces and it would work the same. the large bolt is what is hold…

That's indeed a very naive conclusion. Once that bearing is gone the stress that it would normally allow to escape on account of rotation would be directly transferred to the metal around it and to the bolts holding the whole thing in place. Guess what broke first?

So if that bearing went that's not quite a smoking gun yet but it would definitely be a step closer to a root cause.

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#23

Post by topspin »

WillPostForFood wrote: post #16
CGMthrowaway wrote: post #8

The headline is missing an important bit. Boeing knew of the flaw, and sent a letter to airlines about it. In 2011.

FWIW, the MD-11 was designed by McDonnell Douglas, and manufactured by McDonnell Douglas in 1991, before the Boeing merger. A McDonnell Douglas DC-10 failed in a similar way in Chicago in 1979, so it the issue may go way back.

AA Flight 191 in 1979, 273 dead. American Airlines invented their own engine removal procedure using a forklift and damaged a pylon and mounting bracket. The engine ripped off the wing on takeoff.

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#24

Post by dylan604 »

mmooss wrote: post #18
vsgherzi wrote: post #13

Insane that we can have places like the skunk works create the sr71 and operate on shoe string budgets but the largest passenger plane company in the world can’t accurately assess risk on planes far under the former planes Mach 3 record

I don't see that as a valid comparison. SR-71s could operate with a much higher level of risk than commercial passenger planes. IIRC, SR-71s leaked fuel on the ground, and their wings dragged on the ground without special attachments. Pilots needed special pressure suits, etc. I also expect that they were much less complex than an aircraft that provides a comfortable, pressurized cabin; the high level of safety menti…

the SR-71 leaking fuel on the ground was not a design flaw. it was designed to be operated at speed where things would expand to fill in. if they were filled in on the ground, they'd have no place to expand at speed/temps. the risk assessment was that it was better to leak fuel on the ground rather than blowing up at speed/temp

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#25

Post by dghlsakjg »

vsgherzi wrote: post #13

Insane that we can have places like the skunk works create the sr71 and operate on shoe string budgets but the largest passenger plane company in the world can’t accurately assess risk on planes far under the former planes Mach 3 record

Look up the hull loss numbers on the SR-71. More than a third of them were lost in incidents despite never making contact with the enemy.

It was also insanely expensive to operate: $300k/hour in 1990 dollars, and there aren’t reliable numbers on development costs with all of the black budgets.

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#27

Post by ksaj »

mmooss wrote: post #19

Some are forgetting how risk in technology works: No technology is designed or operated without flaws; that's an absurd approach and impossible to implement. To reduce negative outcomes, we use risk management: assessing the likely lifetime cost of the flaw, and taking cost-effective measures to reduce the risk to an acceptable level. As a familiar example, redundant mass storage drives are much more cost-effective t…

They do mention that the DC10 (this plane's predecessor) was decommissioned for similar issues.

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#28

Post by mrpippy »

dylan604 wrote: post #26
DoesntMatter22 wrote: post #6

Isn't it a mostly Boeing project that is going to go around the moon next month? I'm really afraid for that crew.

Why would you be afraid for them when the Orion capsule worked so flawlessly...oh right.

Are you talking about Starliner? Starliner's 2 flights have been problematic to say the least, but Orion's single (uncrewed) flight went pretty well.

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#29

Post by lashingflank »

One thing that worries me about the current political climate is that everything can be politicized. Do we know that behind the scenes Boeing wasn't paying a bribe for better treatment in the report? Or do we know that this report is especially damning because they refused to bribe? I guess we never knew for sure but the level of corruption now is so high I just have no faith that there hasn't been meddling in these investigations. It's the pernicious effect of corruption in a society and I don't think we're ready for it.

Re: Boeing knew of flaw in part linked to UPS plane crash, NTSB report says

#30

Post by khuey »

mrpippy wrote: post #28
dylan604 wrote: post #26

Earlier quoted context omitted.

Why would you be afraid for them when the Orion capsule worked so flawlessly...oh right.

Are you talking about Starliner? Starliner's 2 flights have been problematic to say the least, but Orion's single (uncrewed) flight went pretty well.

And Lockheed and Airbus are the prime contractors on Orion, not Boeing.
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