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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

#151

Post by dotancohen »

exabrial wrote: post #107

What the news about Boeing has done is make me pay more attention to commercial aviation in general. The number of aviation incidents is actually pretty crazy, and no, Boeing is not at the center of them despite what the media would have you believe. What is amazing though is the actual injury and fatality rate is really low due to well trained crews and measured responses by air controllers.

The word that you are looking for is resilience I believe. Commercial and GA aircraft are highly resilient, and the procedures built around that industry are highly resilient as well.

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

#152

Post by FabHK »

psunavy03 wrote: post #144
throwup238 wrote: post #118

Earlier quoted context omitted.

That depends on what you mean by “generally safe”. Airline jets are not made to withstand the forces of an aerobatic maneuver and while they can do it in test flight conditions, each time requires pulling the jet out of service afterwards for a full structural inspection.

A barrel roll is a 1-G maneuver and will not overstress an aircraft unless done improperly.

Up to 2 or 3G, but most aircraft should withstand that, even gliders.

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

#153

Post by marcus0x62 »

FabHK wrote: post #127
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…

> they simply did not like this particular plane. …and employed a face-saving (though probably very expensive) way of communicating it.

I think this was way more calculated than that. They made up an issue they knew would be taken very seriously and that would be difficult - in the best of circumstances - to disprove.

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

#154

Post by zthrowaway »

tekla wrote: post #102

I'm going to to laugh at the bad takes on this thread, and await a more accurate report. Dutch roll is undesirable, but its a basic consequence of some converging aeronautical effects.

Yes but the alarming thing here is the damaged PCU...

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

#155

Post by xeromal »

bigstrat2003 wrote: post #146
rollulus wrote: post #108

As a Dutchman the endless list of apparent “Dutch” things never ceases to surprise me. Uncles, courage, ovens, double, going, etc., and a new one to my list: rolls. And none of them means any good.

> And none of them means any good. Dude, Dutch ovens are awesome. One of the most useful cooking tools imo.

Dutch oven also means trapping your partner or kid under the blanket and farting. lol

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

#156

Post by dylan604 »

brandall10 wrote: post #92
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?

Just flew a Max from Denver to Mexico City a couple days back. It was mostly uneventful, but as we were preparing to land the aircraft banked hard to the left and began to experience something akin to this...like it hit a sudden pocket of turbulence at the apex of the turn and began to pogo around. It was minor and far from inducing damage to the vehicle, but in that moment remembered where I was while clenching my b…

> like it hit a sudden pocket of turbulence at the apex of the turn

I wonder if this could have been wind shear? Wind shear was deemed as the cause of the crash for Delta 191[0] on approach to DFW in the 1985. Lots of new equipment was installed after to detect wind shear. I wonder of MEX has that kind of equipment.

[0] https://en.wikipedia.org/wiki/Delta_Air_Lines_Flight_191

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

#157

Post by adolph »

FabHK wrote: post #114
adolph wrote: post #49

Earlier quoted context omitted.

> why [Dutch Roll] wasn't bigger news I think the name is a serious problem. Something like “uncontrolled aircraft orientation” is more descriptive. “Dutch Roll” brings to mind thoughts of “is it better than Swiss Cake Roll?” and “is this news-spam for Hostess brand emerging from bankruptcy?”

There are terms of art, jargon, in many fields that mean something different than the “obvious” reading of the term. I had a discussion with someone on Hacker News recently that just could not understand that “dynamic programming” was a very specific solution technique for a broad range of problems with a special structure, rather than any sort of programming with a dynamic aspect to it.

Agreed. To the question at hand: “why 737-max’s ‘Dutch Roll’ wasn’t bigger news,” my conjecture is the term of art obscures the severity of the problem.

As a point of jargon, “Dutch Roll” is poor because the word roll within aeronautics could refer to an orientation movement or an acrobatic maneuver (and probably other things I don’t know about). The use of an ethnic/national identity as an adjective doesn’t help. Is “Dutch” associated at all with oscillations in two dimensions that are not intended by the pilot?

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

#158

Post by dylan604 »

senordevnyc wrote: post #52
belter wrote: post #21

Earlier quoted context omitted.

It can torn off the engines from the main body structure: https://asn.flightsafety.org/asndb/333926

While true, this was a pretty different situation in that it was 1959 (engineering standards have changed a lot in the last 65 years), and the dutch rolls were being performed intentionally for demonstration purposes.

> engineering standards have changed a lot in the last 65 years

Especially for Boeing where standards are determined by the stock price

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

#159

Post by dotancohen »

Filligree wrote: post #2

This just isn’t Boeing’s decade.

Until the McDonnell Douglas management retires, Boeing will not recover. It's not a matter of an unlucky decade, it's a matter of replacing engineering with MBAing. It's just that the latency between cause and effect are long on the engineering side of this industry.

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

#160

Post by MaxfordAndSons »

agurk wrote: post #123
umvi wrote: post #81

Earlier quoted context omitted.

Not as scary as flying upside down which is what I originally thought based on title alone. Most people are familiar with "barrel roll" but by comparison this just looks like wiggling. Counterintuitively though my understanding is that barrel rolls are generally safe even for large planes since it's a stable 1G maneuver (some jock irresponsible air force pilot used to regularly barrel roll B-52s until he did one too…

I'm not aware of a B-52 being crashed in a barrel roll, but this did make me think of the 1994 Fairchild crash[0] that was caused by a pilot who was known as dangerous due to excessive self confidence. In this case he banked too tightly at low level causing a stall into the ground. The whole crash was caught on camera[1], which is indelibly burnt into my memory. [0] - https://en.wikipedia.org/wiki/1994_Fairchild_Air_…

I'm pretty sure that's the crash GP was referring to. It sort of looks like he could have been going into a barrel roll.
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