
Boeing overhauls quality controls: more high-tech tracking but fewer inspectors - wallflower
https://www.seattletimes.com/business/boeing-aerospace/boeing-overhauls-its-quality-controls-more-high-tech-tracking-but-fewer-inspectors/
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projektfu
Looking at the initial comments, I think people need to read up on statistical
quality control before commenting with strong language about the value of
inspection. Some references.

Shewart, Walter. _Economic Control of Quality of Manufactured Product_ (1931)

Deming, W Edwards. _Out of the Crisis_ (1982)

Taguchi, Genichi. _Taguchi’s Quality Engineering Handbook_ (2005)\

Essentially, inspection is too late in the process to affect the overall
quality. You do need to sample and study your products but your process should
have the capability to produce good products without defects and you should
not be relying on inspection to produce your output. There are exceptions,
such as semiconductor chip lithography, where you are always working at the
limits of the process. Nonetheless, there are many parts of the process that
should not require 100% inspection. For example, wire bonding and packaging.

In your aircraft, would you prefer to know that it was made by a process that
produces parts and assemblies that are well within their specification, or
that it had been made by a defective process but inspected 100%?

~~~
sokoloff
Light airplanes in the 60s and 70s shared a lot of automotive parts, literally
made on the same production line.

The interesting part is something like a voltage regulator, Cessna's
specification was for 100% testing. Ford would accept a statistical sampling
for QC. So, using the same line, a certain number would be inspected, stamped
with a Cessna part number and sold there. The remaining assemblies would be
sold as Ford parts.

[https://www.aircraftspruce.com/catalog/eppages/r15v00a.php](https://www.aircraftspruce.com/catalog/eppages/r15v00a.php)

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sitkack
I am programmer, I don't work in Aerospace, my skin in the game is that I fly
in planes and know people that fly in planes.

The first thing that comes to mind is, how many flaws do these inspectors find
that aren't on the list of checks? Removing the inspectors presupposes that
the entire effect they have on the system is codified in measurements they
take.

Did they run a double blind study with fault injection?

> The introduction of sampling instead of comprehensive inspections of every
> job is a key part of Gonzalez-Beltran’s changes.

By the time the flaws arise due to these changes, the folks that instituted
them will be retired or dead.

I am _not_ disagreeing with holistically transforming manufacturing processes
to reduce (and eliminate error), but automated processes are efficient and
without constant feedback unobserved process flaws are even harder to detect.

Given the importance and criticality of such a move, I am not sure we can
trust Boeing with this decision alone.

> An internal Boeing document providing “talking points” for managers,
> obtained by The Seattle Times, points another motivation for the company:
> faster completion of tasks: “By allowing the mechanic to verify their own
> work, wait time is eliminated.”

> The FAA “endorse and understand this,” Gonzalez-Beltran said.

I think what Boeing has done has automated the assembly, but not necessarily
the inspections. Of course mechanics should perform the operation correctly,
but they shouldn't be verifying their own work.

> Gonzalez-Beltran said these were isolated cases of employees not following
> company procedures.

Priorities are not aligned towards safety, if you have people verifying their
own work, they are incentivized to cheat.

> Gonzalez-Beltran, however, insists he’s getting positive buy-in from
> mechanics who take pride in performing their work without an inspector’s
> oversight.

So the VP asked the line worker his _feeling_, like how hungry he is and what
kind of steak he likes to eat.

Airplanes are not cars, while Poke-Yoke should be applied universally to all
engineering pursuits, it in and of itself is not a complete solution.

[https://en.wikipedia.org/wiki/Poka-yoke](https://en.wikipedia.org/wiki/Poka-
yoke)

~~~
skookumchuck
> I am not sure we can trust Boeing with this decision alone

From the article:

"Boeing cannot move forward with such a radical shift in its manufacturing
processes without the approval of the FAA."

~~~
sitkack
The FAA is too close to Boeing. In a change this large I believe the NTSB
should have over site over the FAA. From the article it appears that the FAA
has rubber stamped the process if layoffs are already in effect.

[https://www.ntsb.gov/investigations/AccidentReports/Reports/...](https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0201.pdf)

------
_Understated_
I felt compelled to comment on this as I am somewhat conflicted in my feelings
towards the automation of the checking process.

I am all for progress and automation where possible but I also like to put my
faith in a human (or multiple humans) then going over it again "just in
case"... in this case it would be someone following behind with another torque
wrench to make sure the first guy hadn't missed something or was maybe using a
defective wrench.

I understand that in many industries, checking samples or batches is the norm.
It can make sense. But we're talking about a plane here... the margin for
error must be tiny.

If my car develops a fault, hell, even if a wheel fell off while driving, I
have a good chance of recovering safely but with a plane, something as
catastrophic as my car wheel scenario could be massive. Plus, you can't pull
over to the side of the road.

Also, with my security head on, I am questioning the smart wrenches (I confess
to knowing nothing about them!). If the torque is electronically programmed,
whats to stop hackers tweaking it a bit. Kind of like in Die Hard 2 where the
bad guys reset ground level to be -200ft. How would we know?. Could someone
change 300nm to be actually 200nm? I assume the inspector will look at an
output to verify these things since they won't be going round with their own
torque wrench now.

Hackers could have a field day with this as it could be years before the plane
develops a massive fault and then you'd never be able to track it.

I've read enough about aircraft computer systems to know that they aren't
perfect as it is!

I dunno. This makes me feel a bit uneasy. I always like to think that planes
are over-engineered and triple-inspected by many humans for a reason.

Maybe I am looking a bit too deep here!

~~~
jen20
> I also like to put my faith in a human (or multiple humans) then going over
> it again "just in case"... in this case it would be someone following behind
> with another torque wrench to make sure the first guy hadn't missed
> something or was maybe using a defective wrench.

A second pass with a torque wrench is probably not such a bad idea, but
multiple _checks_ by humans is not necessarily beneficial.

A few years ago I worked for a company making small-batch pharmaceuticals
(almost exclusively with ingredients drawn and mixed by hand, since the
batches were so small), and the consensus (backed by research) there was that
adding a second human check made quality worse rather than better - the second
checker assumes that the first did the job correctly, and the person doing the
work assumes that mistakes will be caught further down the line.

~~~
sitkack
The solution is for the checkers to be blind, in that they should have no
knowledge of ordering or checks. Everything needs to be independent. It isn't
that the second check made quality worse, it is that knowledge that the second
check is run made the first or second check less rigorous.

1) inject faults to test the testers

2) test diversity, automated and manual

3) test order inversion

The often used alternative is to "be careful" which is not rigorous.

~~~
jen20
Indeed, that is the root cause, rather than a second check itself.

------
baybal2
From 12 years in electronics, I can say that:

Humans are bad at doing tasks that are very simple, but repetitive and
requiring 100% correctness. QC is one of them.

Computers on other hand, are very good at doing exactly same thing, finding
out common irregularities that can be preprogrammed.

------
pytester
Perhaps Boeing should take a step back and reconsider their drive for "safety
automation" given that it didn't exactly work out so well the last time:
[https://www.nakedcapitalism.com/2018/11/boeing-
crapification...](https://www.nakedcapitalism.com/2018/11/boeing-
crapification-lion-air-crash.html)

~~~
sitkack
I am going to excerpt a section because this needs to be known.

> The short version of the story is that Boeing had implemented a new “safety”
> feature that operated even when its plane was being flown manually, that if
> it went into a stall, it would lower the nose suddenly to pick airspeed and
> fly normally again. However, Boeing didn’t tell its buyers or even the FAA
> about this new goodie. It wasn’t in pilot training or even the manuals. But
> even worse, this new control could force the nose down so far that it would
> be impossible not to crash the plane. And no, I am not making this up. From
> the Wall Street Journal:
    
    
        Boeing Co. withheld information about potential hazards associated with 
        a new flight-control feature suspected of playing a role in last 
        month’s fatal Lion Air jet crash, according to safety experts involved 
        in the investigation, as well as midlevel FAA officials and airline 
        pilots.
    
        The automated stall-prevention system on Boeing 737 MAX 8 and MAX 9 
        models—intended to help cockpit crews avoid mistakenly raising a 
        plane’s nose dangerously high—under unusual conditions can push it down 
        unexpectedly and so strongly that flight crews can’t pull it back up. 
        Such a scenario, Boeing told airlines in a world-wide safety bulletin 
        roughly a week after the accident, can result in a steep dive or 
        crash—even if pilots are manually flying the jetliner and don’t expect 
        flight-control computers to kick in.
    

See also, [https://www.aviationtoday.com/2018/11/20/lion-air-
boeing-737...](https://www.aviationtoday.com/2018/11/20/lion-air-
boeing-737-investigation-places-flight-controls-focus/)

    
    
        Indonesian National Transportation Safety Committee (KNKT) officials 
        investigating the Oct. 29  crash initially attributed the most likely 
        cause of the accident to erroneous angle-of-attack (AOA) data. Now 
        those same officials, and several airline pilot unions, claim the 
        flight crew operations manual did not contain critical information for 
        pilots regarding the maneuvering characteristics augmentation system 
        (MCAS) designed to prevent the 737 MAX from stalling.

~~~
sokoloff
That system (MCAS) operates by driving the stabilizer trim. There is, in all
models of 737, a QRH checklist exists that, when/if correctly followed, would
have stopped the trim runaway that started the apparent chain of events
leading to the loss of Lion Air 610.

NNC 9.1 in this document:
[http://jira.icesoft.org/secure/attachment/21680/qrh%20rev36%...](http://jira.icesoft.org/secure/attachment/21680/qrh%20rev36%20-800%2027k.pdf)

Note that items above the dashed line are "memory items" (critical items that
the crew memorizes and executes before referencing the checklists). Note also
that this is the only non-normal-checklist for flight controls that includes
memory items. It's not like we're asking the crew to memorize and react to
thousands of things from memory. Stabilizer trim is important on aircraft of
nearly every size.

To get a 737 type rating, you had to have been familiar with that checklist
and very likely to have demonstrated it in training. I know the media is
trying to hang LA610 on Boeing. As a pilot, I think a substantial amount of
the blame [probably the majority of it] is going to land in the cockpit,
particularly if it turns out they didn't follow that checklist. (It's not
important _why_ the stabilizer is being driven in an uncommanded and
undesirable fashion, just that the crew _stops_ it.)

