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United finds loose bolts on plug doors during 737 Max 9 inspections

theaircurrent.com

201–210 of 773 posts

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#201

Such a crappy aircraft - can we just get rid of these already?

Bolts can be loosened, or fail to be tightened on any aircraft. I suspect this may be a problem with people and/or procedure.

The question is not about bolts, but more about what else is hidden there, what else is mechanically neglected that's waiting in there to take lives

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#203
post #40

Earlier quoted context omitted.

> It means people were careless and sloppy during assembly. Maybe. Could also be incorrect torque specs, bad parts, unexpected vibration in that area, etc. Edit: Yes, none of these are good either. Just saying there are many possibilities.

Those don’t sound very reassuring either. What’s to say that this is the only bolt with incorrect torque spec, or if this part is bad why not others, and if bad parts are not being caught during quality control then what other parts will be next to fail prematurely? And if there are unexpected vibrations in that area, why wasn’t it discovered during test flights? What other vibration issues would they not have accoun…

To be fair, I read recently that another issue with MAX 7 was discovered through flight testing. The issue is that now Boeing wants to exempt plane from safety rules…

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#204

Check out this video showing how the plug is supposed to be installed: https://youtu.be/maLBGFYl9_o?t=540 Some of the bolts that would be loosened when the plug is opened during maintenance have a pin to prevent them from turning. That pin is present in this photo: https://x.com/byerussell/status/1744460136855294106?s=46&t=s... However, the same photo shows other critical bolts that hold the whole hinge on the door a…

The castle nut design requires the use of a cotter or other locking pin.

https://en.wikipedia.org/wiki/Castellated_nut

https://en.wikipedia.org/wiki/Positive_locking_device

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#206

Such a crappy aircraft - can we just get rid of these already?

Force it to develop actually new airplane, not rely on grandfathered type license from 60 years ago.

They keep trying to do that. This mess of a plane is care of Southwest and Ryanair who wanted a re-engined 737, period.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#207

Earlier quoted context omitted.

Or it means the torque specs were a little too low, or too high and stripped, or the bolt threading was defective/spec’d wrong. Or bad metallurgy. Or the spec didn’t specify which order to tighten the bolts, so which direction you go causes different outcomes. Lots of stuff is assembled consistently and carefully “wrong”, but as specified.

Some part of the process -- anywhere from specs to assembly-- had some cost cutting that led to the outcome. The root cause of this problem is something financially motivated.

While I don’t disagree with you that it is possible, it isn’t a very “engineering” approach to declare that is the case without doing a root cause analysis. Stating it as fact is as bad as the MBAs…
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