Southwest FLT 812 Decompression and diversion
Grounded Spanner - roger that.
I thought that perhaps when the main torn section cut loose, it applied a little extra tension ("tug") to its neighbor before breaking free, causing the hump. But normal pillowing makes equal sense. In any case, obviously a section of interest to the investigators, if only because it is the other half of a joint.
I thought that perhaps when the main torn section cut loose, it applied a little extra tension ("tug") to its neighbor before breaking free, causing the hump. But normal pillowing makes equal sense. In any case, obviously a section of interest to the investigators, if only because it is the other half of a joint.
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grounded27
You just might be confusing two different types of 'stress testing'.
See:
1.Stress testing - Wikipedia, the free encyclopedia
2.Stress Rupture & Creep Testing at WMT&R, Inc.
You just might be confusing two different types of 'stress testing'.
See:
1.Stress testing - Wikipedia, the free encyclopedia
2.Stress Rupture & Creep Testing at WMT&R, Inc.
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By that I mean; when there is an aircraft accident, Prune attracts the computer expert who posits the cause as a software problem. The chemist suggests the fuel was faulty. The teacher wonders about the pilot training and the lawyer blames it all on criminal negligence by the designer.
However, if Boeing had implemented a proper safety case, they may well have avoided this mistep.
Aircraft structure is not subject to anykind of risk assesment.
Bonding Conditions
Having built a couple musical instruments, I came to appreciate that gluing is a complex operation. It took hundreds of years to develop bonding technology for wood -- and today the proliferation of new adhesives is truly amazing.
I do love tape adhesives -- but they don't always work
Bottom line -- all adhesives have their particular quirks, some of which take decades to manifest themselves.
Yes, pulling out adhesive tape from the freezer and uncoiling invites condensation.
The amount of condensation depends on the ambient temperature and humidity of the day.
I doubt the Boeing factory floor is an environment where temperature and humidity are precisely controlled.
It may be useful to relate the discovered bond failures to the day they were performed and the temperature and humidity at the time. Are there environmental records of temperature and humidity on the factory floor? We may find ourselves limited to public weather records and then infer from building management procedures what the HVAC would have produced. My experience of building management is that HVAC is managed much more to the dollar sign than anything else
I do love tape adhesives -- but they don't always work
Bottom line -- all adhesives have their particular quirks, some of which take decades to manifest themselves.
Yes, pulling out adhesive tape from the freezer and uncoiling invites condensation.
The amount of condensation depends on the ambient temperature and humidity of the day.
I doubt the Boeing factory floor is an environment where temperature and humidity are precisely controlled.
It may be useful to relate the discovered bond failures to the day they were performed and the temperature and humidity at the time. Are there environmental records of temperature and humidity on the factory floor? We may find ourselves limited to public weather records and then infer from building management procedures what the HVAC would have produced. My experience of building management is that HVAC is managed much more to the dollar sign than anything else
Aircraft structure is not subject to anykind of risk assesment
Everything that we do in designing and certifying aircraft has risk assesment built into it. That's why things break, including acts of God. We do a pretty good job of balancing risks, that's why it is safe to fly.
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I'm 100% serious (and correct).
A probabalistic, risk based approach is only required during certification of systems and equipment. Structure and handling for example are exempt. If they wernet the 2001 AA A300 accident would have been prevented.
).A probabalistic, risk based approach is only required during certification of systems and equipment. Structure and handling for example are exempt. If they wernet the 2001 AA A300 accident would have been prevented.
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A possibility
Depending on type. During heavy inspection lower skins are common to replace, if there are enough skins that need replacement you have 2 options... Replace only a few at a time as not to allow for the hull to torque or often secondary procedure for additional shoring and the hull is shot with a transit allowing for many skins at the same time.
Now if something goes wrong and an aircraft comes off jacks after a multiple skin change, the skin seams could be subject to abnormal stresses. The whole frame being torqued.
Now if something goes wrong and an aircraft comes off jacks after a multiple skin change, the skin seams could be subject to abnormal stresses. The whole frame being torqued.
I'm 100% serious (and correct).
A probabalistic, risk based approach is only required during certification of systems and equipment. Structure and handling for example are exempt. If they wernet the 2001 AA A300 accident would have been prevented.
).A probabalistic, risk based approach is only required during certification of systems and equipment. Structure and handling for example are exempt. If they wernet the 2001 AA A300 accident would have been prevented.
I really can't find fault in your words above, it was only your original statement that I challenged
Aircraft structure is not subject to anykind of risk assesment.
Thus a structure may be specified to a stress limit but therafter "managed" to a life limit.
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OK, I'll cut you some slack, but just tell me old boy what the probability of this piece of structure reaching design life target Boeing had to work to?
Can you answer that? Can you?
The other advantage of apply an SMS philosphy would be that the earlier failures would have resulted in earlier Boeing action.
, but just tell me old boy what the probability of this piece of structure reaching design life target Boeing had to work to?Can you answer that? Can you?
The other advantage of apply an SMS philosphy would be that the earlier failures would have resulted in earlier Boeing action.
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Shell Management -- since you are the one swinging your ISO 31000 hammer at everything, why don't you contact Boeing and then report back to us the answers to your questions.
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I didn't mention ISO 31000:2009 old bean.
That a pretty poor Antipodean drafted standard that is compromised by its application beyond safety.
If you were an aviator, you would know that it is ICAO that defines tsndards in aviation not ISO.
That a pretty poor Antipodean drafted standard that is compromised by its application beyond safety.If you were an aviator, you would know that it is ICAO that defines tsndards in aviation not ISO.
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The affected aircraft gained winglets some time in 2009, is there a possibility that the extra weight of these winglets causes more wing flex which may stress the skin above the original design spec??
Shell Management
Given that they have conducted lots of fatigue tests on similar designs, they would probably statiscicaly expect cracking at about half their target life. Such cracks would be inspectable and a confirmation of their model. Now if the cracks are not easily inspectable then they better half the life expectancy even more and continually adjust their mainteance program based on findings.
Sounds to me like that's where they are.
OK, I'll cut you some slack, but just tell me old boy what the probability of this piece of structure reaching design life target Boeing had to work to?
Can you answer that? Can you?
, but just tell me old boy what the probability of this piece of structure reaching design life target Boeing had to work to?Can you answer that? Can you?
Sounds to me like that's where they are.
This thread is deteriorating rather quickly.
Aircraft are designed and built under massive risk management programs that are driven by parameters set by the insurance industry starting with the hull loss probability. That then gets driven down into the design through Failure mode effects analysis (FMEA) right into the design MTBF's of the components - including the hull.
Those programs do not stop when the aircraft design is frozen, but continue for the life of the aircraft in service or until the company goes under, after which someone else has to be found to assume design authority if the aircraft is to remain in service.
We have one person here (grounded) that confuses bean counting with statistical analysis of failures and doesn't understand what a strain history is either.
To put it another way Grounded, why do you think an automobile manufacturer sets service intervals and component replacement schedules for the cars they make and how do they do it?
P.S. If you ever worked on aircraft replacing lower skins, then they must have been pretty old and crappy aircraft because Boeing started paying attention to bilge corrosion - sealing faying surfaces and filleting with PRC 1422G8 for example, around 1975.
Aircraft are designed and built under massive risk management programs that are driven by parameters set by the insurance industry starting with the hull loss probability. That then gets driven down into the design through Failure mode effects analysis (FMEA) right into the design MTBF's of the components - including the hull.
Those programs do not stop when the aircraft design is frozen, but continue for the life of the aircraft in service or until the company goes under, after which someone else has to be found to assume design authority if the aircraft is to remain in service.
We have one person here (grounded) that confuses bean counting with statistical analysis of failures and doesn't understand what a strain history is either.
To put it another way Grounded, why do you think an automobile manufacturer sets service intervals and component replacement schedules for the cars they make and how do they do it?
P.S. If you ever worked on aircraft replacing lower skins, then they must have been pretty old and crappy aircraft because Boeing started paying attention to bilge corrosion - sealing faying surfaces and filleting with PRC 1422G8 for example, around 1975.
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Sunfish
Aircraft are designed and built under massive risk management programs that are driven by parameters set by the insurance industry starting with the hull loss probability. That then gets driven down into the design through Failure mode effects analysis (FMEA) right into the design MTBF's of the components - including the hull.
Sorry to have offended your profession. I have in depth knowledge of modern corossion preventative programs. CPCP goes way beyond using a variation of tank sealant in joints, I have had factory training by Dynatrol and yes have worked around some old aircraft "quick go wiki it and come back with more slander".
All your statistical analysis is great in general. BUT it is absolutely useless when something fails before you predict it.
To word it another way HRS/CYCLES/ANALYSIS are not worth a damb to the crew and passengers of an aircraft diving for breathable air.
Also events like this allow tools like yourself to change the shelf life of a product, initiate an inspection at an earlier date. I am sure it made you feel like you were doing the world a grand favor. Sir by mentioning you as a tool it is with the utmost respect, persons like yourself create job security for people like myself, we are truely a breed apart.
The only thing exciting in this business are things that can not be predicted, the unpredictable changes the industry.
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winglets, sturcture life
Winglets: I would look more at the additional lift on the wing in critical conditions, which could be transmitted as bending load into the fuselage. That said, given the speed with which Boeing revised the inspection interval without any reference to modifications, I doubt they are relevant.
Structure life: I am intrigued by the suggestions that structures are not subject to risk assessment. This may have been the case decades ago but I thought all recent new aircraft designs had to be tested to show compliance, the so-called fatigue tests. Maybe the 737-300s, being derived from the 1960s -100/200 didn't need such a demonstration, or service experience was used.
Structure life: I am intrigued by the suggestions that structures are not subject to risk assessment. This may have been the case decades ago but I thought all recent new aircraft designs had to be tested to show compliance, the so-called fatigue tests. Maybe the 737-300s, being derived from the 1960s -100/200 didn't need such a demonstration, or service experience was used.
Grounded:
Have you told the aircraft manufacturers, operators and the worlds regulators the wonderful news that all those extremely costly and carefully constructed aircraft maintenance programs they engage in can now be abandoned because failures "just happen"?
Why do you think we bring a particular aircraft in for you to maintain? Do you think we just pick its number out of a hat?
Shell Management, I was taught risk management by Exxon. The starting point for the airline, air traffic control and aircraft manufacturer risk management programs are the acceptable passenger death rates per million miles travelled as well as the calculated cost to the insurers of a fully loaded aircraft crashing in the middle of a block in central London or downtown Manhattan.
All your statistical analysis is great in general. BUT it is absolutely useless when something fails before you predict it.
To word it another way HRS/CYCLES/ANALYSIS are not worth a damb to the crew and passengers of an aircraft diving for breathable air.
Also events like this allow tools like yourself to change the shelf life of a product, initiate an inspection at an earlier date. I am sure it made you feel like you were doing the world a grand favor. Sir by mentioning you as a tool it is with the utmost respect, persons like yourself create job security for people like myself, we are truely a breed apart.
The only thing exciting in this business are things that can not be predicted, the unpredictable changes the industry.
To word it another way HRS/CYCLES/ANALYSIS are not worth a damb to the crew and passengers of an aircraft diving for breathable air.
Also events like this allow tools like yourself to change the shelf life of a product, initiate an inspection at an earlier date. I am sure it made you feel like you were doing the world a grand favor. Sir by mentioning you as a tool it is with the utmost respect, persons like yourself create job security for people like myself, we are truely a breed apart.
The only thing exciting in this business are things that can not be predicted, the unpredictable changes the industry.
Have you told the aircraft manufacturers, operators and the worlds regulators the wonderful news that all those extremely costly and carefully constructed aircraft maintenance programs they engage in can now be abandoned because failures "just happen"?
Why do you think we bring a particular aircraft in for you to maintain? Do you think we just pick its number out of a hat?
Shell Management, I was taught risk management by Exxon. The starting point for the airline, air traffic control and aircraft manufacturer risk management programs are the acceptable passenger death rates per million miles travelled as well as the calculated cost to the insurers of a fully loaded aircraft crashing in the middle of a block in central London or downtown Manhattan.
Shell Management, I was taught risk management by Exxon. The starting point for the airline, air traffic control and aircraft manufacturer risk management programs are the acceptable passenger death rates per million miles travelled as well as the calculated cost to the insurers of a fully loaded aircraft crashing in the middle of a block in central London or downtown Manhattan.
they don't have a hand in managing safety. They enter into it to gauge what the overall statistical risk is and what level of their money to set aside for the aftermath.And nobody in regulated aviation goes around with managing a known problem against the number of dead bodies.
Risk management can address known problems that are understood well enough (all the potential causal chains in a link) such that the risk of all the links coming together within the time frame that corrective actions are implemented are far less than 1 single catastrophic event.
It's the unknowns that catch us by surprise and this thread subject is just another example of a surprise. But now that it's no longer an unknown a corrective action will be implemented (closing out the risk) in a period of time where only a surprise (unforeseen combination) will result in a catastrophe.
If critical combination in the future turn out to still be unknowns after an investigation then expect forced inspection and limitations forever. If this can't be reliably performed then expect the limitations in operations to be severe.
This is nothing more than managed risk at least far better than the average person freely lives their own life.
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Risk Management is based on a theory of what should happen, it is nothing more than financial liability. Reality changes your factors and the variable factor of events we can not predict is reality. I do not understand the argument here? Our environment our reality is certainly unpredictable, thus my point. What should be is a big part of society, what is, is real.