| > I disagree. You are acting like this is a cut and dry situation wherein the Boeing advice that this was not safety critical is just wrong on it's face. That assessment was made 15yr ago (perhaps by "old good boeing" engineers) and on a part already under a lot of scrutiny from the other MD11 that lost an engine. Sure they could be wrong, but I wouldn't bet on it so confidently. Well, those good old Boeing engineers and their management have misled the world more than once and no longer deserve the benefit of the doubt. That advisory is black-and-white, there is no arguing with what it says or does not say, you can read it for yourself. If your conclusion is the same as Boeing's then that's fine, you can have a different opinion. My conclusion is that if a load bearing component has these kind of potential issues that you need to act with an abundance of caution because of the price in case you get it wrong. Yes, that bearing only moves a few degrees. But this is not about how much it moves, this is about what happens when it can not move and given the forces involved the outcome of that is fairly predictable, in spite of your previous statements. There is absolutely no way in which if that bearing is seized or otherwise constrained that this is safe. > I would be very surprised if there weren't also maintenance failing of some sort here. I explicitly left the door open for that. But regardless, this bearing should have never failed. There are a couple of HN members whose pension depends on Boeing stock so I can see how this might ruffle some feathers but this is not a company that has behaved in a morally responsible way when it came to issues such as these om the past and you are effectively already blaming the maintenance people with your 'I would be very surprised if there weren't also maintenance failing of some sort here.'. That is jumping to conclusions. I would not be surprised if it were the case, but I also would not be surprised if it wasn't the case. That's the degree to which Boeing has squandered its erstwhile stellar reputation. But, since you feel comfortable attacking my reputation from behind your shield of anonymity I suggest you flesh out your profile and Bio and tell us a bit about yourself and why you feel so emotionally involved in this. |
You and potato followed that wrong path and unfortunately didn't correct me or yourselves. I tried to correct myself later (see my sibling comment), but I wouldn't be surprised if I've made another huge cockup with the facts.
> Yes, that bearing only moves a few degrees
It certainly does not move a few degrees (except maybe after a crash).
Thinking back to my one undergrad mechanics paper, I think the design purpose was to make torsions equal zero, so that the mechanical analysis would be tractable.
The torsions should still be extremely low because nothing can rotate (except maybe a tiny amount due to deformations).
If we can't get the engineering facts straight, then our opinions on engineering management are likely to be even more pointless and flawed.
You seem to have gone off the rails as much as potato.
The report seems to be implying that the broken bearing is the cause of the accident. The bearing was still in place after the accident so presumably the bolt didn't shear. If the engine has full acceleration then the engine is pitching upwards against the wing and the force on that bearing is upwards?
I think the report implied the fire occurred at the same time as the structural failure.
What might be the chain of events from a broken bearing to a fire?