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Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

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Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#71

Post by ceejayoz »

_heimdall wrote: post #67
ceejayoz wrote: post #47

Earlier quoted context omitted.

I'd note Airbus is seeing the same pattern. The 737-MAX's A320neo competitor, for example: https://en.wikipedia.org/wiki/List_of_Airbus_A320neo_family_... 1,689 orders in 2023, 154 in 2024. https://en.wikipedia.org/wiki/List_of_Airbus_A220_orders_and... 141 orders in 2023, negative 12 in 2024. As a result, I presume the explanation is less "no Boeing" and more something like "orders have a reporting lag" or "2023 was…

These stats alone seem like way more interesting news, suprised I haven't seen that before. I wonder why plane orders from the two biggest manufactures have dropped so dramatically and what it means economically. My mind immediately goes to whether airlines are quietly preparing for an expected downturn, or if airlines aren't selling to corporations because they're selling to governments and militaries. That could de…

I wouldn't read too much into it yet; 2023's numbers look like they're abberantly high, which is probably the airlines catching up after the little economic hiccup we all had in 2020.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#72

Post by glitchc »

tjpnz wrote: post #20
blakesterz wrote: post #4

"Dutch Roll is a coupled out of phase movement of the aircraft as result of weakened directional stability (provided by the vertical tail and rudder), in which the aircraft oscillates around its vertical as well as longitudinal axis (coupled yaw and roll)." That sounds pretty scary. I wonder why it wasn't bigger news when it happened last month?

Here's a video demonstrating it: https://youtu.be/Zmjam1evDD4

Dutch roll was particularly pernicious with trijets. It has to do with thrust vs lift vectors having different offsets (origins) relative to the cg. Sometimes they would add stabilizers to the tail to correct for this, but eventually manufacturers gave up on the design.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#73

Post by banannaise »

HPsquared wrote: post #54
belter wrote: post #41

Earlier quoted context omitted.

The FAA reported: "AIRCRAFT EXPERIENCED A DUTCH ROLL, REGAINED CONTROL AND POST FLIGHT INSPECTION REVEALED DAMAGE TO THE STANDBY PCU, OAKLAND, CA." and stated the aircraft sustained substantial damage, the occurrence was rated an accident.

Standby PCU sounds like a control system. Was that a cause or effect of the event?

The PCU in this context is the part that moves the rudder. PCU issues were common on the 737 in the 90s[0] although that's... probably?... not relevant here.

[0] https://en.wikipedia.org/wiki/Boeing_737_rudder_issues

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#74

Post by moffkalast »

Waterluvian wrote: post #50
marcus0x62 wrote: post #24

Years ago, my father in law ( a heavy jet mechanic) got sent to China for two months as part of a team to diagnose and fix a recurring dutch roll complaint on a particular airframe. This was for a A300-series flown by a large freight carrier. The local mechanics couldn’t figure it out, so this team was assembled from the mechanics at headquarters to fix the plane. They inspected the plane and found no damage. They ha…

Eek… I’d never want to fly a plane that’s beneath me. I’d prefer it to be at the same altitude.

Well unless you're an air launched cruise missile operator.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#75

Post by ragebol »

shdon wrote: post #22
ragebol wrote: post #12

For anyone else (besides me, being Dutch) wondering about the name: https://en.wikipedia.org/wiki/Dutch_roll?useskin=vector#Name TL;DR: it's from ice skating where there's a similar move. But no idea why it's called that in ice skating.

Ice skating... Interesting... My guess was it having to do with ships rocking side to side. Maar waarom een schaatsterm?

Maybe the ice skaters took it from ships, also an old Dutch tradition I suppose.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#76

Post by MVissers »

_heimdall wrote: post #67
ceejayoz wrote: post #47

Earlier quoted context omitted.

I'd note Airbus is seeing the same pattern. The 737-MAX's A320neo competitor, for example: https://en.wikipedia.org/wiki/List_of_Airbus_A320neo_family_... 1,689 orders in 2023, 154 in 2024. https://en.wikipedia.org/wiki/List_of_Airbus_A220_orders_and... 141 orders in 2023, negative 12 in 2024. As a result, I presume the explanation is less "no Boeing" and more something like "orders have a reporting lag" or "2023 was…

These stats alone seem like way more interesting news, suprised I haven't seen that before. I wonder why plane orders from the two biggest manufactures have dropped so dramatically and what it means economically. My mind immediately goes to whether airlines are quietly preparing for an expected downturn, or if airlines aren't selling to corporations because they're selling to governments and militaries. That could de…

Could be related to high interest rates and investments being more expensive. Also, I believe that Airbus has a 10 year backlog on their newest planes, so no point in shelling out a lot of cash right now for 10 years down the line.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#77

Post by CoastalCoder »

rl3 wrote: post #59
CoastalCoder wrote: post #30

Earlier quoted context omitted.

If it's a software issue, I'd think owners would be pretty clear on its status on each plane. But for physical defects, yeah that's scary.

> If it's a software issue, I'd think owners would be pretty clear on its status on each plane. Ha. I have some bad news for you: https://www.bloomberg.com/news/articles/2019-06-28/boeing-s-...

I can't read that article, but I'm assuming (hoping?) that even if the software is flawed, there's still clarity about which source code / build configuration is installed on a given plane.

Contrast that to the allegedly faked test results, and known defects, of the planes' physical characteristics.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#78

Post by throwup238 »

epolanski wrote: post #39
amarant wrote: post #25

It kinda bothers me that airlines are still placing orders for new Boeing airplanes. Taking delivery of old orders is one thing, since they can't really back out of those, but placing new orders implies that some level of trust remains for this company, and I just don't see how that makes any sense at all?

1) Even if the max had hiccups, plenty of them, it is an absolutely safe airplane by any measure. 2) Your fleet may mostly be formed by Boeing airplanes, having all of those move to Airbus airplanes is also a safety issue. Pilots have to re-learn and even forget things they accrued and evolved to react instantly for decades. At some point you need to weigh the odds of increasing human error vs relatively safer Airbus…

> 1) Even if the max had hiccups, plenty of them, it is an absolutely safe airplane by any measure.

Except fatalities.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#79

Post by banannaise »

bell-cot wrote: post #13

For those unfamiliar with Dutch Roll - https://en.wikipedia.org/wiki/Dutch_roll Noteworth there: The 2013 fatal crash of a Boeing KC-135R, after its rudder PCU failed. The article places preliminary blame (for the new incident) on the 737-8's rudder PCU. One might wonder about the design, components, and processes commonalities between rudder PCU's for the KC-135R, and 737-8.

The 737 rudder PCU also had a defect in the 90s that caused a series of major incidents, although obviously that's been fixed since:

https://en.wikipedia.org/wiki/Boeing_737_rudder_issues

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