Boeing 737 MAX production hit by a new defect in part from Spirit AeroSystems 1

[tommj]

https://www.kansas.com/news/business/aviation/article274324980.html

So who knows what they did wrong specifically?

 

[SWComposites]

As far as I know, details have not been disclosed.

 

[davefitz]

super-glue and duct tape again?

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[SWComposites]

it appears to be a production issue, not an "engineering failure".

 

[EdStainless]

The report that I saw referred to a production process issue.
Perhaps steps being done out of order or an inspection done at the wrong step?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[waross]

Apparently Boeing is doing warranty repairs on planes already in service.

https://www.seattletimes.com/busine...duction-hit-by-a-new-defect-in-supplier-part/

Spirit, which builds the entire MAX fuselage in Wichita, Kansas, notified Boeing on Wednesday that “a non-standard manufacturing process” was used during the installation of two fittings at the vertical tail of certain 737 MAX 7, MAX 8 and MAX 8-200 models, as well as on the 737-based P-8 military plane for the U.S. Navy.

The fittings involved are two of eight points where the vertical fin is attached to the fuselage.

That means the parts don’t conform to Federal Aviation Administration regulatory requirements.

https://www.reuters.com/business/ae...gs-31-mln-hit-737-fuselage-defect-2023-05-03/

May 3 (Reuters) - Spirit AeroSystems Holdings Inc (SPR.N) said on Wednesday it expects a $31 million hit to full-year gross profit from disruptions and rework related to a Boeing 737 MAX fuselage production problem, and that more related costs are anticipated.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[SWComposites]

“a non-standard manufacturing process” was used during the installation of two fittings

which likely means one of:
- improper hole drilling and/or deburring of the holes
- improper fastener installation
- improper shimming in the joint
though there could be a bunch of other possibilities.

the fact that the defect is stated to not be an immediate safety issue likely means that it affects fatigue performance, not static strength.

 

[TenPenny]

I was hoping this would be a buying opportunity, but BA share price is up again, so no luck. Last May, I bought BA at $125 per share, after some bad news, and it's up to $203 today.

 

[Alistair_Heaton]

There was something about how they were torquing some fixtures as well.

I watched our technicians change a tyre the other day and torquing the "bolts" was alot more involved than grunting on a torque wrench until it went clack and giving the tyre a kick which was the way we did it on the Jetstream.

They tightened then changed the setting, then backed off, Changed again and tighten again.

 

[FacEngrPE]

Progressive tightening in a pattern is the recommend approach for any flange connection. Bolt Tightening Sequence: Why it Matters. I can not see why airplane wheel hubs should be different.
See also ASME PCC-1 which works for connections with no gasket but need to have no tendency to loosen in service.

 

[Alistair_Heaton]

I love watching our technicians working. They produce some works of art with locking wire.

Definitely don't want anything to loosen keeping the wheel on.

 

[Alistair_Heaton]

found the AD

https://drs.faa.gov/browse/excelExt...D-2023-06364-0000000000.0001?modalOpened=true

 

[SWComposites]

wrong AD; the Spirit issue is on the Max, not the -700/-800; and is for the aft fuselage fittings, not engine anti-ice ducts.

 

[SWComposites]

from an article today:

The quality issue was discovered only a few weeks ago and has been identified on two of the eight fittings on which the vertical tailfin is positioned on the fuselage of the aircraft. The issue, which has been traced back to aircraft first produced in 2019, affects the 737 P-8A, the MAX 7, MAX 8, and MAX 8200. Boeing said last week in its Q1 earnings call that some 170 aircraft in inventory need rework. Another 500 delivered aircraft could also need the rework, which includes removing the tailfin and some structures to get access to the fittings.

 

[waross]

I'm guessing that it may have been a similar issue.
Possibly, because of a tight location of the fittings, they were torqued improperly.
Most probably with a claw or open-end attachment.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[JohnRBaker]

Possibly, because of a tight location of the fittings, they were torqued improperly.

If this is true, then this could be more of a design error rather then purely a production problem.

When I was working as a machine designer, we always had to keep in mind that the systems that we were designing had to be assembled with the normal tools available in the shop or in the field when they were being installed, as well as how one would go about maintaining and repairing the machinery after years of being in service. And in our industry, the tools that we could expect to be employed were pretty basic.

Now it is true, that if there were issues found on the assembly floor where a fastener couldn't be properly installed and tightened, it was up to the shop to notify engineering that changes needed to be made. Unfortunately, we had shop guys who prided themselves in how they could get around these sorts of flaws, and get the machine out without raising a stink as it were. One time there was an issue with a machine that we built and sold 10 or more per year and this one design had been basically unchanged in 20 years. But then the guy who was the lead on that assembly group retired and he forgot to tell his replacement about how he had been modifying a handful of fasteners so that the machine worked as expected. Of course, the new guy used what he was given and the machine failed to cycle because it jammed. We in engineering was perplexed because there had been no problems in 20 years and yet here it was, locked-up like a rock. Only then did we discover that the old mechanic had been having the heads of about four bolts per device, machined so that they would fit without causing the machine to jam. All it took was specifying a low-profile fastener and we were good to go.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[waross]

When I was working as a machine designer, we always had to keep in mind that the systems that we were designing had to be assembled with the normal tools available in the shop or in the field

Not every manufacturer does that.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[JohnRBaker]

In our business sector, we were considered the premier supplier of machinery for large commercial bakery operations and as such, we were able to charge a premium for our products. So it was the responsibility of everyone in the company to see to it that our reputation was maintained and that out customers continued to feel that they got the value that they were paying for.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[dik]

When I was younger, I was pretty sure that automobile designers never had to repair one of the vehicles they designed.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[LittleInch]

Doesn't seem to have put Ryanair off buying their new Max-10s though.

https://www.theguardian.com/busines...plans-rapid-expansion-after-new-boeing-orders

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.