Rudder issue that plagued the Boeing 737 throughout the 1990s • Hacker News Board

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#241

Post by pedrocr » Thu, Mar 14, 2019, 8:42 PM UTC

atomicbeanie wrote: post #234

pedrocr wrote: post #203

Earlier quoted context omitted.

The Concorde was not retired directly after the crash. It flew for three more years and was retired for financial reasons. The crash probably reduced the demand though and thus contributed.

I think that is inaccurate. One fleet was grounded quickly. The 30 million Kevlar tank linings were underestimated in cost I think dramatically. As for profit, I am not sure the aircraft was ever a profit center. Any reasonable observer saw Non-recoverable Engineering Expenses that the company any could never recover from as a result of having to mitigate a new safety requirement onto an old aircraft that was never d…

What is inaccurate? The accident happened in 2000 and the last flights were in 2003 by both airlines. What do you mean by one fleet being grounded quickly?

The exact motives for retiring the plane are hard to know. Safety almost surely played a part if nothing else by reducing demand. I was just correcting that you seemed to be saying the plane has been retired after the accident when it did in fact return to service.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#242

Post by southern_cross » Thu, Mar 14, 2019, 8:44 PM UTC

Boeing certainly hasn't been inspiring a lot of confidence lately, given that decisions like this:

https://www.seattletimes.com/business/boeing-aerospace/boein...

have apparently been leading to decisions like this:

https://www.seattletimes.com/business/boeing-aerospace/air-f...

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#243

Post by hopler » Thu, Mar 14, 2019, 8:45 PM UTC

rb808 wrote: post #233

To me its interesting that they wouldn't redesign the part as it would be admission of causing previous crashes? Kinda scary that the lawyers rule USA at the end of the day. Its easy to blame Boeing for faults like this but its a miracle that these things fly so reliably with so many moving parts and human involvement.

Lawyers don't design planes. CEOs who intentionally lie about their planes' safety do.

Without lawyers, those CEOs could go on killing people and never have any accountability.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#244

Post by rsweeney21 » Thu, Mar 14, 2019, 8:46 PM UTC

My previous company made software for DOTs. Over the years I learned that DOTs assign a dollar amount to human lives/deaths when calculating the cost benefit ratio of implementing roadway safety improvements. It very much reminds me of the acceptable number of deaths mentioned in the article. DOTs don't like talking about this of course.

There should be a law that grants companies safe harbor for reporting and fixing defects in their product without the risk of accepting liability. Sort of like self-whistle blowing.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#245

Post by dsfyu404ed » Thu, Mar 14, 2019, 8:47 PM UTC

js2 wrote: post #229

dsfyu404ed wrote: post #198

Earlier quoted context omitted.

In my opinion the GM ignition switch thing was over blown. Getting worn out and sloppy and failing in one of several ways (e.g. turning the car off unexpectedly) is not an atypical failure mode of old ignition switches. The only reason it was a big deal was because wealth-ish people (i.e. not someone driving a 1993 Corolla) driving fairly new (at the time) vehicles died. Their cover up was somewhat scummy but I don't…

> over blown The faulty ignitions have been linked (by GM itself) to 124 deaths. > old ignition switches Five years is not an old ignition switch. > should have had to cover up On June 5, 2014, Valukas' report on the recall was made public. In it, he asserted that the company's failure to fix the defective switches sooner was not due to a cover-up on the company's part, but rather due to "their failure to understand,…

>As well, the case study doesn't mention cover up once, but instead points out a variety of secondary issues: inadequate communication, a lack of understanding of the problem, a lack of urgency, a lack of oversight, and company culture.

That was a typo on my part. Regardless the media portrayed it as a coverup.

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#246

Post by hopler » Thu, Mar 14, 2019, 8:48 PM UTC

Kavenerinds wrote: post #240

organsnyder wrote: post #199

Earlier quoted context omitted.

Given that the Max crashes both happened shortly after takeoff, I'd be more interested in a per-flight statistic. But I'm not sure how the industry does it.

The industry/NTSB/FAA generally cares more about flight hours, but I agree with you. Both of these accidents happened shortly after takeoff. I am surprised that no accident has happened during landing.

Is the same sensor used the same way in landing?

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#247

Post by Erlich_Bachman » Thu, Mar 14, 2019, 8:50 PM UTC

rsweeney21 wrote: post #244

My previous company made software for DOTs. Over the years I learned that DOTs assign a dollar amount to human lives/deaths when calculating the cost benefit ratio of implementing roadway safety improvements. It very much reminds me of the acceptable number of deaths mentioned in the article. DOTs don't like talking about this of course. There should be a law that grants companies safe harbor for reporting and fixing…

Is there realistically any other way to do this though? The value of life, as estimated by a human in a generic situation is presumably infinite. However, companies, governments, regulating bodies, etc, have to regulate actual physical measures, which cost money, time etc- all very finite things. These agents need to act in actual physical environment like for example limited budgets or having to choose between two different safety measures. At some point the human life is going to have to enter that equation, if we are going to be talking about safety issues. How do you calculate en equation with finite and infinite variables without assuming a finite value for the human life?

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#248

Post by hopler » Thu, Mar 14, 2019, 8:52 PM UTC

DuskStar wrote: post #170

marcosdumay wrote: post #125

Aviation has an well known acceptable risk level at around 10^-9 for each issue. That's the number that leads government intervention, pilot procedure designing, aircraft designing and everything else. It's expected to lead to a less than 10^-6 chance of accidents per flight. (Somebody calculated the B783 Max odds on 4*10^-6 yesterday, what is a crazy high level.) That number has been higher in the past, and is movin…

> Somebody calculated the B783 Max odds on 4*10^-6 yesterday, what is a crazy high level. I think that may have been me (1/250000), but that was based on a couple of generous assumptions - two crashes across 4 flights/day on 350 planes for an average of 365 days. Unfortunately I think a more reasonable flights/day number is 3 or lower - a lot of Max 8s are on longer routes - and the flight day average is almost certa…

When something happens 2 times, even a simplistic error analysis is going to show at least a 3x range in probably (2+/-1 incidents is 1 to 3)

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#249

Post by hopler » Thu, Mar 14, 2019, 8:54 PM UTC

georgecmu wrote: post #16

This reminded me of the Yak-42 jackscrew failure due to a design defect, which caused a crash killing 132 onboard in 1982 [1]. The entire fleet was grounded for more than two years until the full investigation was completed and the defect was fixed. Three design engineers were convicted. [1] https://en.wikipedia.org/wiki/Aeroflot_Flight_8641

Convicted of what? Smells like scapegoating.

"The investigation concluded that among the causes of the crash were poor maintenance, as well as the control system of the stabilizer not meeting basic aviation standards”

Re: Rudder issue that plagued the Boeing 737 throughout the 1990s

#250

Post by jethro_tell » Thu, Mar 14, 2019, 8:54 PM UTC

wycy wrote: post #93

cat199 wrote: post #53

Earlier quoted context omitted.

Why single out southwest specifically in this hypothetical scenario? If any airline seems 'people focused' I'd think it would be them..

Southwest is probably called out specifically here because they're somewhat unique in the airline world in that their entire fleet is 737s. This allows them to save on maintenance costs since there's so much commonality among their fleet, but puts them in more peril when something affects the entire class of craft.

Also, because boeing said,

'we should label these switches like this and put them here', and southwest said,

'no, that will change the type and we will have to retrain pilots, we'd rather have things be the same type with an asterisks and just let our pilots know than retrain'

And because southwest is the largest consumer of the 8max, Boeing did it. From what I understand, that was a precondition of sale for the contract.

And the result it seems is that the plane can act in a way that is confusing to people who are expecting one behavior and seeing another, this comes right down to labeling switches as one thing, when they are kinda another.

My assumption, and this will probably be borne out in the investigation, is that, because southwest was part of the decision process here, they are at very little risk because of a little additional lite pilot training where they point out these switches are labeled wrong and this behavior will seem funny but this is what it's going to do. But not all airlines are going to train like that, it's the same type right?