
Unexpected cracking found on critical Boeing 737 Next Generation part - erentz
https://komonews.com/news/local/exclusive-unexpected-cracking-found-on-critical-boeing-737ng-equipment
======
9nGQluzmnq3M
For context, the 737 NG is previous iteration of the 737 (before the MAX) and
among the most popular aircraft ever built, with over 7000 in service.
Grounding this would absolutely cripple the airline industry.

However, the NG also has an excellent safety record, and 35000 cycles is
equivalent to 5 flights (takeoff & landing) every day for 10 years. So while
this may lead to extra checks on older aircraft, it's highly unlikely to cause
a MAX-style global grounding.

~~~
samstave
What is the actual safety record of the B-52, which i subjectively consider to
be the safest machine in history.

How would the B-52 match up against modern commercial airliners? (Does anyone,
other than boeing, even track this stat?)

The calc would be something along the lines of;

Date-of-design -> completion, testing, commissioning, hours in flight -
accidents, crashes,pilot error, time in service, fuselage age, etc...

I am subjectively of the opinion that the B-52 is the greatest aircraft ever
made.

~~~
ceejayoz
[http://www.airsafe.com/events/models/rate_mod.htm](http://www.airsafe.com/events/models/rate_mod.htm)
indicates 79 fatal 737 incidents with about a quarter billion flights under
their belt.

[https://www.globalsecurity.org/wmd/systems/b-52-safety.htm](https://www.globalsecurity.org/wmd/systems/b-52-safety.htm)
indicates 76 B-52s destroyed in accidents across 7.5 million flight hours.

They're not perfectly comparable sets of numbers, but the B-52s look
_substantially_ riskier on a per-hour basis.

~~~
samstave
Thank you for this!

76 machines destroyed, carrying (obstensibly) nukes.. from 7.5mm flight miles
== .00001% risk of failure.

Did I do the math correctly?

With ZERO nuke detonations...

And a flight carcass of nearly 70 years old now???

~~~
xvector
It is almost impossible to get a nuke to accidentally detonate. Has nothing to
do with the B52. Let alone 1 in 76, we’re talking 1 in millions.

------
hansthehorse
There is a 9 year old documentary on two Boing whistleblowers describing
cracking probability on the 737ng. It's an hour long:
[https://www.youtube.com/watch?v=IaWdEtANi-0](https://www.youtube.com/watch?v=IaWdEtANi-0)

~~~
alexis_fr
Extremely interesting. Especially, around 19-21 minutes, we find the same
problem as on 737 Max: Boeing has the delegated authority from the FAA to
certify their own processes and parts.

I’m never flying Boeing again. They were hammering crucial parts to fit,
provoking crackling; redrilling holes when the hole was 3 inches apart,
endangering the whole structural integrity; painting it all green and sending
that to production.

The documentary is about the circles of the airframe structure, not about the
wing forks of today’s article, so that makes one new type of botched work from
Boeing.

~~~
peteretep
> I’m never flying Boeing again

I suspect you were intending this to be obvious hyperbole, but also this will
be very difficult if you’re flying at all regularly. While you can have a look
at the equipment the airline thinks it’ll be flying at booking time, there’s
no guarantees about which plane will actually show up, and the airline isn’t
going to refund your ticket because they decided to swap out their A350 for
their 787 for operational reasons.

~~~
kzrdude
All this plane talk makes me curious, if there are any airlines that tell you
ahead of time what planes they are using for a route? I guess they'd now be
even less inclined to tell.

~~~
jadell
The information is almost certainly available on the page where you see the
search results and choose your flights. Probably right next to or near the
flight numbers. It is on every major US carrier's search results. I don't know
about any of the OTAs: Expedia, Kayak, etc.

~~~
ComputerGuru
It’s there but it isn’t guaranteed nor part of the sales contract.

~~~
jadell
According to the fine print (and carriers' past actions), nothing on an
airline ticket is guaranteed as part of the sales contract; not the plane
type, flight numbers, arrival/departure times, baggage handling, connections,
and, thanks to overbooking, not even the fact that you have a seat on the
plane.

------
newnewpdro
If a part's made of aluminum and undergoes cyclic stress, even staying within
its instantaneous modulus of elasticity, it _will_ eventually crack.

Note the aluminum curve in the graph here [0], it _never_ levels off
horizontally.

My understanding is this effectively means the modulus of elasticity for
aluminum parts is forever diminishing. Aluminum is a metal that's "work
hardened", it's basically becoming increasingly brittle the more cyclic stress
it experiences.

I'd been told in the past that commercial planes are regularly X-rayed for
cracks as part of their maintenance, because of their extensive use of
aluminum.

None of this should be a surprise except that it's supposedly "unexpected" in
the pickle fork. These vehicles have always been high maintenance machines, in
order for them to be safe all the structural aluminum must be regularly
inspected for cracks, the cracks should be expected and parts replaced as
needed.

[0]
[https://en.wikipedia.org/wiki/Fatigue_limit](https://en.wikipedia.org/wiki/Fatigue_limit)

Edit:

Out of curiosity I did some digging for photos of this part and more
information, this thread delivers some insightful links and citations:

[https://www.pprune.org/rumours-news/625886-737ngs-have-
crack...](https://www.pprune.org/rumours-news/625886-737ngs-have-cracked-
pickle-forks-after-finding-several-jets.html)

~~~
corbani
The modulus of elasticity of aluminum does not change with cycling (or
basically with anything else but big temperature differences).

Fatigue is a damage accumulation process, that does not show in the most
obvious properties, like modulus or strength.

The aviation regulations changed a long time ago from requiring to avoid
cracks to requiring to have structures that can operate with cracks long
enough to for them to be detected, as is exactly the case here. Of course
nobody design planes to crack, but the regulations reflect the realization
that completely avoiding cracks is impossible ...

------
anon91831837
Unsurprising given the 2010 Al Jazeera revelations of the Boeing-Ducommun
conspiracy and cover-up: critical structural elements that were supposed to be
CNC machined by Ducommun were crudely made by hand and Boeing managers ordered
them installed into 737 NG (-600, -700, -800, -900) anyhow. And then when a
blue-ribbon panel of Boeing employees went to find out what happened, their
findings were buried and no corrective action was taken. 737 NG's are flying
around with substandard critical structural components like spars and the
areas around doors, leading to several fuselage breakups on hard landings and
runway overruns, which has killed at least several passengers to date. In past
similar incidents, aircraft fuselages survived intact. There's a very real
possibility that one or more 737 NG's may breakup in heavy turbulence, hard
landings and runway overruns at any time, and Boeing knows about it, but has
done nothing to remedy it.

[https://youtu.be/IaWdEtANi-0](https://youtu.be/IaWdEtANi-0)

~~~
dehrmann
> leading to several fuselage breakups

[citation needed]. It's what AJ is positing, but it's presented like a
correlation, I don't think investigators called that out an a cause of the
breakups, and it's been 10 years since that was made and this doesn't seem to
be a major problem. One thing I read suggested that the fuselage is strongest
at the wing, so the break happens away from that section. That, and hard
landing is an understatement; One landed short of the runway, another overshot
it, and one dropped onto it.

[https://commons.wikimedia.org/w/index.php?title=File%3AAnima...](https://commons.wikimedia.org/w/index.php?title=File%3AAnimation_-
_Turkish_Airlines_crashed_during_approach%2C_Boeing_737-800_-_Dutch_Safety_Board.webm)
(4:55)

------
kjar
I’m not flying anymore. Between the GHG annual personal emissions and the
stunning staggering massively deadly failures of rushed Boeing product
launches. Finally I will note the whole damn process is dehumanizing and
terrible.

~~~
heavyset_go
The worst part of these revelations is that the aviation industry is exalted
as _the standard_ other industries should look up to when it comes to safety.

If Boeing can't escape the perverse incentives that tempt every company, then
what company can and why are we relying on this economic model to drive such a
high stakes industry?

~~~
txcwpalpha
>The worst part of these revelations is that the aviation industry is exalted
as the standard other industries should look up to when it comes to safety.

I don't see why that's "the worst part". Flying is the safest mode of travel,
and among airliners the 737NG is one of the safest planes in aviation history.
The fact that cracks have been discovered doesn't change that, and the routine
inspections which have discovered these cracks and will lead to them being
fixed is precisely the reason why these aircraft, and the aviation industry as
a whole, are so incredibly safe.

~~~
gmueckl
In fact, finding and _correcting_ faults in airplanes happens constantly. Up
until the Boeing debacle this was just something that happend while nobody was
looking. Now journalists are riding the scare wave generated by the
relevations following the 737 max crashes and dragging all these fairly
routine happenings out into the open with disproportionate coverage.

~~~
desc
The primary reason why air travel is so safe is that each and every failure in
production becomes a major news item for days.

So the system broke somehow, and the news will keep hammering it until someone
somewhere learns their lesson. We hope.

Yes, they will go after a bunch of false positives too in the process, but the
thing with weeding out the true negatives reliably is that you have to be
paranoid about the false positives too.

Cutting the margins too fine and skipping the 'paranoid, inefficient' checks
is how we got here.

Focusing a really big spotlight on the entire industry is part of the feedback
loop.

~~~
gmueckl
The media is ignoring 80 to 90 percent of incidents that happen in aviation
that lead to investigations. A fair bunch results in technical changes to
aircraft, but it is mostly too boring for a layperson.

~~~
specialist
The Politics of Attention means we've always been reactive. Too much outrage.
Too few eyeballs. Resulting in triage. Made worse as investigative journalism
has been gutted these last few decades. Made worse as engagement driven
business models (ad revenue) begat outrage culture.

------
alan5
> Engineers design pickle forks to last the lifetime of the plane, more than
> 90,000 landings and takeoffs, a term known as "flight cycles" in the
> aviation industry, without developing cracks.

That number made me do a double take. Seems planes never stay on the ground
for very long.

~~~
axaxs
Not an aerospace engineer, but this seems like a weird way to measure airplane
life. A transpacific plane could have 1/10 the cycles but equal airtime, and
one would think that the stresses of flight are worth considering. Wonder why
it's not measured in hours, like say, tractors, or miles flown. Do we measure
any other engined vehicle this way?

~~~
agurk
There are a variety of ways that age of something can be measured with two
common examples in everyday life being people and cars commonly measured in
years and kms/miles respectively. The metric chosen is one that adds value for
understanding the impact.

Aeroplanes and their components do have a lot of different ways of having
their ages measured, depending upon what one cares about. Engines are a good
example of something where the hours spent running is usually the most
salient.

For fusalages, as we're talking about here, pressurisation cycles is actually
very important in pressurised airframes. This is because it is the main source
of material fatigue which is a major cause of issues - usually in the form of
cracks. This was discovered the hard way with the de Havilland Comet[0].

Smaller non-pressurised planes are normally measured in total flight hours,
but the effect of repeatedly pressuring and depressuring is so great that it's
the biggest factor that will affect the life of the bigger airframes.

[0]
[https://en.wikipedia.org/wiki/De_Havilland_Comet#Accidents_a...](https://en.wikipedia.org/wiki/De_Havilland_Comet#Accidents_and_incidents)

~~~
axaxs
Very informative, thank you.

------
v8engine
For those curious about how this part looks, Boeing Pickle Fork graphic
illustration:

[https://www.pprune.org/rumours-news/625886-737ngs-have-
crack...](https://www.pprune.org/rumours-news/625886-737ngs-have-cracked-
pickle-forks-after-finding-several-jets.html#post10581606)

------
tobib
A lot of text providing very little information.

------
basicplus2
<A ‘pickle fork’ is the part that connects the fuselage with wings to manage
stress and torque loading on the structure>

See link for pictures of design

[http://newsinflight.com/2019/09/28/boeing-workers-found-
new-...](http://newsinflight.com/2019/09/28/boeing-workers-found-new-cracks-
on-boeing-737ng-not-max/)

------
m0zg
>> We're told this is very much an ongoing investigation, and that it's
unclear whether or not this is a widespread issue.

TL;DR: a crack in a critical part was found in one plane during a routine
inspection. But you wouldn't know that unless you read all the way to the
middle of the article. This is a non-story engineered to create outrage and
clicks.

~~~
kube-system
> Another source tells us Boeing quickly reported the issue with the single
> plane to the FAA last week, and now more planes with similar cracking have
> been found.

~~~
m0zg
How many? Could be as few as 2. Out of thousands.

~~~
simion314
It is clearly not all planes were disassembled and checked, from what I read
it is not a routine check so it will take a while until all planes are
checked. So yeah they may have found only 2 more planes with cracks because
they only checked 2 more planes that were already disassembled.

