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Loose Bolts Found on 737 MAX 9 Aircraft

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According to reports, at least five aircraft were found to have loose bolts on plug doors. (airlinegeeks.com) More...

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avionik99
avionik99 10
Loose bolts would still have needed to have the cotter pin installed, thus not allowing them to come off. They do not define "loose" so that can just be the slack introduced when the mechanic backs off the nut to align the bolt hole with the castellated nut spacing for cotter pin installation.
bobbolew
Robert Lewis 3
Good comment.
bkoskie
Billy Koskie 18
I don't care if Boeing did it or Spirit Aerospace did it. There are 3 fundamentals here - tighten the fastener pin/wire tie the fastener so it cannot loosen, and inspection to assure the tightening/pinning was completed. The fact this didn't occur is incredibly bad.
augerin
Dave Mathes 3
...I dono' bro, that's a pretty hefty set of requirements :(
wx1996
wx1996 6
Looks like the aircraft went to an MRO center for a couple weeks. Did the MRO center take off the door for access? And why did Alaska have to send a new aircraft to MRO center?
mbrews
mbrews 7
Mod work took place in Oklahoma City at AAR mro. To install the sat.wifi dome antenna atop fuselage. Open question about the work & steps during mods. For example, was a cabin pressure test ( leak test ) done at OKC, and what method & pressures were involved….
scotflyer
scott kennedy 2
Intellisat install…
dann403aln
Dan Nelson 9
With several aircraft found with the loose bolts from different airlines, there will be a investigation of the origin of the problem.
mbrews
mbrews 3
Lets stick with the specific aircraft - N704AL when the plug door blew off. And who last worked on It's door.

The method of rigging the door plug is a "kludge" any way you slice it. The Boeing baseline option for < 180 pax would have been to install a (better=secured) exit door and de-activate it.
DaveIsaacs
David Isaacs 0
Do you mean install but not include functionality? In an emergency would passengers realize this exit did not function?
mbrews
mbrews 1
To the pax inside cabin, it would seem similar to this Alaska bird. But with a more robust fastening system & a tiny porthole window. See Chris Brady’s fine explanations on YouTube Boeing 737 Technical Channel
dann403aln
Dan Nelson 9
Seriously, a sub-contactor building the fuselage can't tighten bolts? Fire them and whoever at Boeing hired them.Sick and tired of these companies hiring sub contractors who are going to cut corners every way they can.
mbrews
mbrews 15
As I said on a different thread.

Most folks are overlooking the fact that this bird spent 10 days at OKC, late November to Early December. Likely Mods at an MRO . Still NOTHING said publicly who else worked on this a/c and what work was done ....

Meaning - who was the latest organization to have hands-on this A/C ? And did they need to open and close the door plug for any work. Hold off the Spirit / Boeing bashing. Don't AssUme something you can't prove with facts
scotflyer
scott kennedy 6
I agree. Safety check are the 3 subsequent pressurization annunciator panel alerts. Correctly deleted from ETOPS flights until properly and definitively sourced. System works but how long can source fault be deferred ?
raleedy
ALLAN LEEDY 0
I wonder how you would track a fault that randomly turns a pressurization warning light on. It’s just easier to keep flying the aircraft until the failure reveals itself?
mbrews
mbrews 6
You schedule it out of service, and task the proper team to effectively troubleshoot the problem.

All this talk of Benign alarms, remove plane from ETOPS routes, etc really bugs me. IMO, it simply means that financial incentives overrode the safety concerns.
ltullos
Larry Tullos 1
I couldn't agree more. Even a child understands 3 strikes and you're out!

I would like to know how often undiagnosed pressurization warnings occur as well as FAA and EASA (European) rules for dealing with them.
ghstark
Greg S 5
"This bird ..."
They've now found numerous MAX 9's across United and Alaska Air with loose bolts.
GeorgeDinius
George Dinius 2
Spirit is not a typical contractor. They were spun off from Boeing. In any case, Boeing just bought themselves a world of grief.
d0ugparker
Doug Parker 1
The subcontractor getting fired goes somewhere else to infect the next place they go, so train them, then fire them. Otherwise, their weak link status silently follows them to the next job, and keeps them hidden, a weak link that's getting shuffled somewhere else.

Fix and educate that weak link, regardless. That attitude improves the system.

The knee-jerk reflex reaction is to simply kill them off, but that attitude and that approach really needs to be pointed out and that attitude really needs to be stopped.

An attitude of "train them then fire them" leaves the overall system in a better state than just firing them.
babaganoosh
mike Renna 3
I am just an aviation fan but am I wrong? My mind is blown that these aren't installed from the inside. Really can't be pulled out even if not bolted on? inside higher pressure is pushing the plug against the frame / can't fall out. I'm trying to think what it was - not sure a plane or something else, but heard of some similar situation where they specifically said the item is bigger than the opening / installed from the high pressure side to prevent this.
rthornto
Is this a design problem i.e., properly tighten bolts but subjected to vibration become loose.
Certainly - is this a "locked" type bolt (regardless of vibration - remain in place and functional?
raleedy
ALLAN LEEDY 7
Castle nuts with cotter pins. Shouldn't work loose if properly installed. Big "if".
avionik99
avionik99 2
Just read where the prelim report states they could not determine if the bolts were ever installed or not. Looking at the way its designed I find that hard to believe. If the bolts were installed how did all 4 disappear without a trace? They would still be attached as they were cottered in place!
KennyFlys
Ken Lane 2
Somewhere along the line, either quality control inspections got lax or were ignored and skipped over.

This would not happen on a Navy aircraft. I or any other tech would be facing the skipper at mast if not referred to courts martial.
miltonfarm
mark webb 3
I agree totally. I'm navy trained and our standards are high. We also watched each others back and checked each other's work, even if there was no requirement to do so. This was done to reduce error due to fatigue.
dann403aln
Dan Nelson 5
No matter who may have worked on this aircraft Boing should have the over site and responsibility for the quality of the work. No excuses for shoddy work is acceptable when any aircraft is involved.
mbrews
mbrews 3
Wishful thinking. Boeing not directly involvedd with 3rd party MRO's who work on the aircraft AFTER it is delivered. They operate with their own certificates and sign-offs
adainv
adainv 2
The bolts could not listen if torqued properly and the cotter pin was installed properly. Therefore, sloppy union workmanship and incompetent inspectors.This is the bottom line!
bobbolew
Robert Lewis 1
I wish I could see this assembly in person. Even with pictures and video it is hard to see the whole picture. The first thing I would focus on is the possibility of cracking the upper guide fitting by over-torquing the bolt.
dann403aln
Dan Nelson 2
There is no room for a lack of discipline or careless in aviation operations
Once a aircraft is in the air there are very few second chances. Professionalism and execution is required from everyone at every level.
bobbolew
Robert Lewis -1
I'm tempted to say thanks Captain obvious, but I won't do that.
rthornto
Are we really discussing poorly trained folks (due to shortage / covid etc) or lack of skilled?
TimDyck
Tim Dyck 5
Or just a lack of giving a crap.
augerin
Dave Mathes 2
...best reply ever...
miltonfarm
mark webb 1
Why are they not lock wired ????? They would not undo at all. Obviously using a split pin is not doing the job.
avionik99
avionik99 6
Split pins (cotter keys) do the job extremely well. When installed!! Most of the people that has viewed this with me agree that the bolts were most likely never installed.
nasdisco
Chris B 1
This is on Boeing. Already reported that the additional equipment did not involve the plug.

The plug was removed by Boeing during the assembly of this aircraft. Boeing simply cannot be trusted to assemble aircraft.

First loose tail bolts not this. How many more people have to die?
mbrews
mbrews 3
You’re forming a conclusion, when investigation is about 5 % done. NTSB needs to fully investigate ALL that occurred during 10 days at OKC.
aurodoc
aurodoc 1
What I don't understand is if a fuselage is designed and built with an emergency exit and some airlines choose to fill it in with a "plug" why not keep it as a real emergency door with a real locking mechanism. I cannot say it is ever bad to have another route to escape in an emergency. There is a row of seats there anyway with maybe 1 less seat.
My 2 cents.
rthornto
Is this a design problem i.e., properly tighten bolts but subjected to vibration become loose.
Certainly - is this a "locked" type bolt (regardless of vibration - remain in place and functional?
bobbolew
Robert Lewis 2
Over-torqued bolts can crack the structure or part they are designed to secure. Indeed, some bolts secured with castellated nuts are meant to be installed finger tight only and secured with cotter pins. Don't ask me how I know.
TimDyck
Tim Dyck 2
How do you know…
bobbolew
Robert Lewis 1
OK, OK, I'll confess. I and another mechanic were replacing the aileron booster assembly on a C-130H. The lower right mounting lugs (double, in line) go one on top and one below the mounting lug attached to the aft bulkhead on the center wing box, and are secured with a bolt and castellated nut, cotter-pinned. The maintenance instructions said to finger tight the bolt only. We overlooked that and torqued it and cracked the lug(s) on the booster assembly.
bobbolew
Robert Lewis 2
BTW, thanks for asking!
TimDyck
Tim Dyck 2
Thanks for the explanation. I was expecting something more along the lines of "I told you not to as me that". But one mechanic to another we have all done something we shouldn't have because we got into a hurry and forgot to read the instructions thoroughly. The important thing is to own the mistake fix the mistake and then learn from from the mistake and never do it again. People's live depend on us being humble enough not try to cover our mistakes up.
d0ugparker
Doug Parker 2
Compare this comment to @Dan Nelson's comment about firing the sub. In both cases something was done wrong, but here're two different consequences.

In the same way repair instructions need one correct way only, how mistakes are handled need to be addressed the same way.

Fire the person responsible?
Retrain the person responsible?
Allow the person to admit the error and correct it?

It raises need for additional process reform. However, this thread is about the door plug—not about process reform, so it needs its own thread.

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