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Is the latest whistleblower proven at least partially incorrect?
An important piece of reporting is published in the edition of Aviation Week dated April 22-May 5. Headlined, "Credibility Crisis", the article reports in some depth about the case Boeing has made publicly as to the safety of the 787 with particular reference to, and emphasis on, the allegations and/or concerns articulated by the whistleblower who testified recently before the Permanent Subcommittee on Investigations.
Before a summary of key aspects of the AW&ST reporting, a couple of sidebars should be stated. First, and this is based on mere SLF/attorney background - though some of background is in employment law and labor relations - the move by Boeing to South Carolina seems to be a major factor in what has gone wrong in that aseembly plant and its operations. Not only flight away from union representation of the labor force, not only moving out of the historic airplane-building culture of Seattle, but those factors seem pretty evident in the demise of the safety culture - as was testified to in the other Senate Committee hearing (Senate Commerce, with the three membeers of the Expert Panel).
Second, the AW&ST article notes that the whistleblower's attorney's letter to the FAA included various documents. The letter "cited internal Boeing documents - including a white paper from engineers with similar critiques - to support his claims" and the magazine requested copies of such documents but the law firm "did not provide them." One could speculate about various reasons why not, but it would be just speculation. That said, it is quite tempting to say that the law firm representing the whistleblower should make those documents public.
The article's main point is to report on the analysis and evidence Boeing has compiled showing that the assembly of 787 airplanes has not produced any unsafe conditions, in any meaningful context. There was a media briefing given by a "vice-president and chief engineer for mechanical and structural engineering".
As the article reports, extensive examination of in-service airplanes did not reveal any degradation or weakening of the fuselage sections where "joins" are made. Inspections were done at heavy maintenance intervals and extensively of the in-service fleet. (Referring to the article, 980 airframes were built before the gaps/shims problem was discovered and acknowledged; eight have undergone heavy maintaenace checks at the 12-year interval and 671 have been inspected at the six-year interval.) No evidence was found to support the claims made by the whistleblower with regard to long-term degradation of the integrity of the structure.
Significant evidence also was derived from the fatigue test article.
I'm obvioulsy (real obviously, sorry to have to say) not an engineer, so I may not be doing a worthy job of summarizing the article. I do say, as a sometime-vocal critic of Boeing, anyone who cares about the "latest Boeing news" - whether to contribute to restoring the once-preeminent engineering powerhouse or to helping it slide into oblivion - owes it to a decent sense of intellectual honesty to read the article.
Though Boeing has significant heavy lifting to do to restore a meaninful safety culture (don't take my word for it, take it from the Section 103 Expert Panel), that imperative does not equate to this specific whistleblower's substantive claim about airframe structures being correct. I'll be happy to stand corrected (or, in equivalent terms, to return to my seat and fasten my . . . ) if it is shown the article does not actually establish that his claims (about the structure, not about the lack of safety culture) are incorrect. And if they are in fact incorrect, well . .. it would be pedantic to divert into points about the employment law principles and process. But that said, perhaps it isn't so curious after all why his attorneys did not file a retaliation claim with the Department of Labor (which, as all know, other whistleblowers did file).
Before a summary of key aspects of the AW&ST reporting, a couple of sidebars should be stated. First, and this is based on mere SLF/attorney background - though some of background is in employment law and labor relations - the move by Boeing to South Carolina seems to be a major factor in what has gone wrong in that aseembly plant and its operations. Not only flight away from union representation of the labor force, not only moving out of the historic airplane-building culture of Seattle, but those factors seem pretty evident in the demise of the safety culture - as was testified to in the other Senate Committee hearing (Senate Commerce, with the three membeers of the Expert Panel).
Second, the AW&ST article notes that the whistleblower's attorney's letter to the FAA included various documents. The letter "cited internal Boeing documents - including a white paper from engineers with similar critiques - to support his claims" and the magazine requested copies of such documents but the law firm "did not provide them." One could speculate about various reasons why not, but it would be just speculation. That said, it is quite tempting to say that the law firm representing the whistleblower should make those documents public.
The article's main point is to report on the analysis and evidence Boeing has compiled showing that the assembly of 787 airplanes has not produced any unsafe conditions, in any meaningful context. There was a media briefing given by a "vice-president and chief engineer for mechanical and structural engineering".
As the article reports, extensive examination of in-service airplanes did not reveal any degradation or weakening of the fuselage sections where "joins" are made. Inspections were done at heavy maintenance intervals and extensively of the in-service fleet. (Referring to the article, 980 airframes were built before the gaps/shims problem was discovered and acknowledged; eight have undergone heavy maintaenace checks at the 12-year interval and 671 have been inspected at the six-year interval.) No evidence was found to support the claims made by the whistleblower with regard to long-term degradation of the integrity of the structure.
Significant evidence also was derived from the fatigue test article.
I'm obvioulsy (real obviously, sorry to have to say) not an engineer, so I may not be doing a worthy job of summarizing the article. I do say, as a sometime-vocal critic of Boeing, anyone who cares about the "latest Boeing news" - whether to contribute to restoring the once-preeminent engineering powerhouse or to helping it slide into oblivion - owes it to a decent sense of intellectual honesty to read the article.
Though Boeing has significant heavy lifting to do to restore a meaninful safety culture (don't take my word for it, take it from the Section 103 Expert Panel), that imperative does not equate to this specific whistleblower's substantive claim about airframe structures being correct. I'll be happy to stand corrected (or, in equivalent terms, to return to my seat and fasten my . . . ) if it is shown the article does not actually establish that his claims (about the structure, not about the lack of safety culture) are incorrect. And if they are in fact incorrect, well . .. it would be pedantic to divert into points about the employment law principles and process. But that said, perhaps it isn't so curious after all why his attorneys did not file a retaliation claim with the Department of Labor (which, as all know, other whistleblowers did file).
Thank you WillowRun 6-3 for this great summary. I assume we can't access that article online, so you took the burden to list the key facts?
Recently I read the signs and also "wasn't fully convinced" of the issues with the aft fuselage structure. This is another sign.
While these 6 and 12 years checks (C and D checks I assume) could suffer from missing practical experience with carbon fiber composites assessment, at least with the combination Boeing and the fuselage proportions and connection method...
... the fatique test should tell a lot about the level of degradation for this very circumstances. Depending on the test methods and test circumstances of course. Engineer Sam S, the whistleblower, complained that he never received those details after he requested them. Maybe that's why he sticks to his assessment. Like when the tests in reality had been the initial program structure tests with perfect tolerances, which did not consider out of tolerance gaps and "brutal methods" to make it fit. These would be a rather doubtful assessment in this case.
But I have now even more the feeling that experts could focus on the other issues first without missing much.
Just my humble opinion, with room for improvement.
Recently I read the signs and also "wasn't fully convinced" of the issues with the aft fuselage structure. This is another sign.
While these 6 and 12 years checks (C and D checks I assume) could suffer from missing practical experience with carbon fiber composites assessment, at least with the combination Boeing and the fuselage proportions and connection method...
... the fatique test should tell a lot about the level of degradation for this very circumstances. Depending on the test methods and test circumstances of course. Engineer Sam S, the whistleblower, complained that he never received those details after he requested them. Maybe that's why he sticks to his assessment. Like when the tests in reality had been the initial program structure tests with perfect tolerances, which did not consider out of tolerance gaps and "brutal methods" to make it fit. These would be a rather doubtful assessment in this case.
But I have now even more the feeling that experts could focus on the other issues first without missing much.
Just my humble opinion, with room for improvement.
Last edited by waito; 26th Apr 2024 at 18:48.
An important piece of reporting is published in the edition of Aviation Week dated April 22-May 5. Headlined, "Credibility Crisis", the article reports in some depth about the case Boeing has made publicly as to the safety of the 787 with particular reference to, and emphasis on, the allegations and/or concerns articulated by the whistleblower who testified recently before the Permanent Subcommittee on Investigations.
Before a summary of key aspects of the AW&ST reporting, a couple of sidebars should be stated. First, and this is based on mere SLF/attorney background - though some of background is in employment law and labor relations - the move by Boeing to South Carolina seems to be a major factor in what has gone wrong in that aseembly plant and its operations. Not only flight away from union representation of the labor force, not only moving out of the historic airplane-building culture of Seattle, but those factors seem pretty evident in the demise of the safety culture - as was testified to in the other Senate Committee hearing (Senate Commerce, with the three membeers of the Expert Panel).
Before a summary of key aspects of the AW&ST reporting, a couple of sidebars should be stated. First, and this is based on mere SLF/attorney background - though some of background is in employment law and labor relations - the move by Boeing to South Carolina seems to be a major factor in what has gone wrong in that aseembly plant and its operations. Not only flight away from union representation of the labor force, not only moving out of the historic airplane-building culture of Seattle, but those factors seem pretty evident in the demise of the safety culture - as was testified to in the other Senate Committee hearing (Senate Commerce, with the three membeers of the Expert Panel).
Two factors to keep in mind - prior to 2020 (i.e. Covid), roughly half of the 787's were assembled in Everett by the IAM. Despite claims by the union to the contrary, there is scant evidence that the Everett built 787s were of better quality than those made in South Carolina.
Second, all the 737 and 767-2C/KC-46 are assembled in the Puget Sound area by IAM union labor. It's not like those have been without issues....
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I'm not sure I put much stock in the 'lack of union workforce' drumbeat (especially since much of that drumbeating seems to be originating with the IAM Union).
Two factors to keep in mind - prior to 2020 (i.e. Covid), roughly half of the 787's were assembled in Everett by the IAM. Despite claims by the union to the contrary, there is scant evidence that the Everett built 787s were of better quality than those made in South Carolina.
Second, all the 737 and 767-2C/KC-46 are assembled in the Puget Sound area by IAM union labor. It's not like those have been without issues....
Two factors to keep in mind - prior to 2020 (i.e. Covid), roughly half of the 787's were assembled in Everett by the IAM. Despite claims by the union to the contrary, there is scant evidence that the Everett built 787s were of better quality than those made in South Carolina.
Second, all the 737 and 767-2C/KC-46 are assembled in the Puget Sound area by IAM union labor. It's not like those have been without issues....
It may be a case of the S.C. plant being the source of two prominent whistleblowers and (given Steelworkers roots in this SLF/atty) maybe IAM claims have sounded especially strong. Also, in prior threads, iirc going back even before Lion Air, the move to S.C. was attributed to non-union workforce goals by various posters. (and possibly were given too much credence).
I scanned the AW&ST article again now, twice, and there is no discussion of S.C. airframes as compared to airframes assembled in Everett. I think the reporting is not based on one plant being more of a problem than the other.
waito: thanks for acknowledging the post.
And I'm pretty sure the article is published as subscription-paywall. There's also a Check 6 podcast but don't know how available it is.
Was the fatigue testing done on a fuselage with the specific fault ? That is one with the excessive gaps present?
The fatigue characteristics of riveted aluminum structures are very well understood, however all composite structures are quite new. I would be interested in hearing from a structures expert on how well these types of structures resistance to degradation can be evaluated.
The fatigue characteristics of riveted aluminum structures are very well understood, however all composite structures are quite new. I would be interested in hearing from a structures expert on how well these types of structures resistance to degradation can be evaluated.
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I apologize in advance to the AW&ST interests for quoting from behind the paywall, but it's an important issue. I'll let the well-informed interpret this section on the fatigue testing. (The person quoted is the vp and chief engineer etc as noted previously.)
In-service reviews of the oldest and most used airframes underpin results from tests done early in the program to validate the 787’s design—tests that unknowingly trialed production flaws discovered years later.
“The most impactful data is the data that we got from our full-scale fatigue test,” Chisholm said. “The build condition [was] the same as what we saw in the later build.”
Put another way, the same nonconformances that crept into the first 980 aircraft were present in the fatigue test article. While the revelation does not reflect well on Boeing’s original quality assurance process, it bolsters the argument that its design—including material selection and tolerances—is robust.
“In over 165,000 cycles, there were zero fatigue issues in the composite structure,” Chisholm said.
The tests, which began in September 2010 on ZY998, the third 787 airframe built, ran through 2015 and simulated entire flights, from taxi through ascent, cruise, descent and back to taxi (AW&ST Dec. 21, 2015-Jan. 3, 2016, p. 51). Targeted at creating a dataset for the airframe’s durability, the
tests subjected the structure to loads that simulated more than 3.6 times the design life of 44,000 flight cycles.
Testing was conducted in a steel rig weighing more than 1 million lb. at the Boeing manufacturing plant in Everett, Washington. The rig included more than 100 mechanical connections to push, pull and twist the 182-ft.-long fuselage, wing forward leading edge and vertical stabilizer. The 787 structure incorporated over 3,000 sensors that evaluated more than 40 million discrete load conditions as the airframe was subjected to shear forces, bending moments and torsion loads typically experienced during five flight conditions ranging from benign to extremely turbulent.
Although some parts failed over the course of testing, they were all metallic. Components and parts that cracked or failed prematurely included a metal bearing pad in the main landing-gear support structure and tie-rod end lug and support fittings. There were no catastrophic failures during the test, Boeing adds.
The fatigue-test airframe incorporated additional sensors along the side-of-body wingbox joint, which was reinforced after earlier static tests revealed weakness in the area. The redesign, which pushed back first flight of the 787 to December 2009, was validated in static tests the previous month and later incorporated into ZY998. Compared with fatigue tests on earlier metallic airframes, the 787 test unit included more sensors on various stiffener terminations and more extensive periodic inspections than required by the baseline maintenance program.
Average 787 utilization is about 600 cycles per year, Boeing said. The busiest aircraft operate 900-1,400 cycles annually, Aviation Week Network Fleet Discovery data show. The highest-time 787, an All Nippon Airways 787-8, has flown 16,500 cycles in its 11-year service life.
The 44,000-cycle life expectancy is reflected in the extent of the 787 tests compared with previous fatigue tests on conventional aluminum-built airframes, such as the 777, which completed the then-record number of 120,000 simulated cycles in 1997. This represented the equivalent of 60 years in operation or twice the 777’s design service objective (DSO) of 60,000 flights. The DSOs of the 787 and 777 have both been significantly extended beyond previous generations, such as the 757 and 767, which underwent fatigue tests simulating 100,000 flights, or twice a 20-year DSO of 50,000 flights.
_______________________________________________________
In-service reviews of the oldest and most used airframes underpin results from tests done early in the program to validate the 787’s design—tests that unknowingly trialed production flaws discovered years later.
“The most impactful data is the data that we got from our full-scale fatigue test,” Chisholm said. “The build condition [was] the same as what we saw in the later build.”
Put another way, the same nonconformances that crept into the first 980 aircraft were present in the fatigue test article. While the revelation does not reflect well on Boeing’s original quality assurance process, it bolsters the argument that its design—including material selection and tolerances—is robust.
“In over 165,000 cycles, there were zero fatigue issues in the composite structure,” Chisholm said.
The tests, which began in September 2010 on ZY998, the third 787 airframe built, ran through 2015 and simulated entire flights, from taxi through ascent, cruise, descent and back to taxi (AW&ST Dec. 21, 2015-Jan. 3, 2016, p. 51). Targeted at creating a dataset for the airframe’s durability, the
tests subjected the structure to loads that simulated more than 3.6 times the design life of 44,000 flight cycles.
Testing was conducted in a steel rig weighing more than 1 million lb. at the Boeing manufacturing plant in Everett, Washington. The rig included more than 100 mechanical connections to push, pull and twist the 182-ft.-long fuselage, wing forward leading edge and vertical stabilizer. The 787 structure incorporated over 3,000 sensors that evaluated more than 40 million discrete load conditions as the airframe was subjected to shear forces, bending moments and torsion loads typically experienced during five flight conditions ranging from benign to extremely turbulent.
Although some parts failed over the course of testing, they were all metallic. Components and parts that cracked or failed prematurely included a metal bearing pad in the main landing-gear support structure and tie-rod end lug and support fittings. There were no catastrophic failures during the test, Boeing adds.
The fatigue-test airframe incorporated additional sensors along the side-of-body wingbox joint, which was reinforced after earlier static tests revealed weakness in the area. The redesign, which pushed back first flight of the 787 to December 2009, was validated in static tests the previous month and later incorporated into ZY998. Compared with fatigue tests on earlier metallic airframes, the 787 test unit included more sensors on various stiffener terminations and more extensive periodic inspections than required by the baseline maintenance program.
Average 787 utilization is about 600 cycles per year, Boeing said. The busiest aircraft operate 900-1,400 cycles annually, Aviation Week Network Fleet Discovery data show. The highest-time 787, an All Nippon Airways 787-8, has flown 16,500 cycles in its 11-year service life.
The 44,000-cycle life expectancy is reflected in the extent of the 787 tests compared with previous fatigue tests on conventional aluminum-built airframes, such as the 777, which completed the then-record number of 120,000 simulated cycles in 1997. This represented the equivalent of 60 years in operation or twice the 777’s design service objective (DSO) of 60,000 flights. The DSOs of the 787 and 777 have both been significantly extended beyond previous generations, such as the 757 and 767, which underwent fatigue tests simulating 100,000 flights, or twice a 20-year DSO of 50,000 flights.
_______________________________________________________
Last edited by WillowRun 6-3; 27th Apr 2024 at 01:36.
Have a listen to the Aviation Week “Check 6” podcast of April 19. It provides an excellent explanation of what the whistleblower’s allegations are all about, as well as the challenges of composite construction.
The podcast is available to anybody, along with transcript. Good insight.
WR63:excellent.
Disclaimer: I'm Electric Engineer with no experience in the matter I discuss here. It's just a superficial opinion from someone with technical backgrounds.
IMO almost all is addressed by Boeing. Especially the fatigue test over 5 years and simulating 3x the maximum life cycles, was done with an also imperfect fuselage with exceeding the tolerances.
Also IMO, the remaining issue is the suspected overforcing of the composites for measurement of gaps in production. Causing possible microcracks, and causing possible gaps out of tolerance when finally assembled with lower force. This was not simulated in the fatigue test as far as I know.
There's no perfect experience with all that on the free market that we can hope to get a verdict easily.
I assume the fuselage issues form a lower risk than most people expect. It's not an urgent issue. The question is, can they detect individual cracks in time on the ["overbent" and "overgapping"] fuselages in time? Does it help to buy back an older airframe with this known condition and perform an accelerated fatigue test?
WR63:excellent.
Disclaimer: I'm Electric Engineer with no experience in the matter I discuss here. It's just a superficial opinion from someone with technical backgrounds.
IMO almost all is addressed by Boeing. Especially the fatigue test over 5 years and simulating 3x the maximum life cycles, was done with an also imperfect fuselage with exceeding the tolerances.
Also IMO, the remaining issue is the suspected overforcing of the composites for measurement of gaps in production. Causing possible microcracks, and causing possible gaps out of tolerance when finally assembled with lower force. This was not simulated in the fatigue test as far as I know.
There's no perfect experience with all that on the free market that we can hope to get a verdict easily.
I assume the fuselage issues form a lower risk than most people expect. It's not an urgent issue. The question is, can they detect individual cracks in time on the ["overbent" and "overgapping"] fuselages in time? Does it help to buy back an older airframe with this known condition and perform an accelerated fatigue test?
Pegase Driver
First disclaimer :I am not an composite specialist not engineer, but I fly composite gliders since 50 years, and I even own one now. I do not do the heavy maintenance on it but the regular 25h/50h and annual ones. Unlike in aluminium Cracks in standard composite ( e.g. fibreglass) are easily detectable and easily repairable. On the other hand Carbon composites does not pre-crack, it normally shatters in one go. no warning. , hence a strict G- limits and a non-extensible shelf life.
I read somewhere that , unlike many other parts, the 787 fuselage is made of : " carbon laminate composite" , . so my guess is the force (i.e. how many Gs " were used to force the parts in place) was probably under its limits otherwise it would have shattered. Immediately.
But waiting for specialists to comment..
I read somewhere that , unlike many other parts, the 787 fuselage is made of : " carbon laminate composite" , . so my guess is the force (i.e. how many Gs " were used to force the parts in place) was probably under its limits otherwise it would have shattered. Immediately.
But waiting for specialists to comment..
The way fatigue cracks propagate through metal is very different from the way damage accumulates in composites. In particular, fatigue cracks in metal form and progress at very small stress loads - 10% or less of the maximum yield load**. The cracks start at some tiny mismatch in grain structures and, because the crack is into metal crystals, the size of the front edge of the crack is as little as a single atom in size, causing a huge stress concentration.
I think composites tend to fail from separation of the fibers from the matrix (usually epoxy for carbon fiber.) The usual final failure is by rupture of the fibers from the matrix which is usually rather explosive as the fibers can store a lot of energy from the combination of strength and elasticity, but the composite can accumulate damage with even the smallest loads, a characteristic shared with aluminum.
For much more about composite fatigue failure than is suitable to type here see Principal Features of Fatigue and Residual Strength of Composite Materials Subjected to Constant Amplitude (CA) Loading, section 2.5. The Hierarchy of Damage. It's an NIH report and mostly technical, but the 2.5 section gives a good overview.
**I have seen metal parts that failed in use where more than 90% of the original material had succumbed to the fatigue crack and only 10% or less remained to be twisted loose; a load that was very small compared to the strength capacity of the undamaged part.
I think composites tend to fail from separation of the fibers from the matrix (usually epoxy for carbon fiber.) The usual final failure is by rupture of the fibers from the matrix which is usually rather explosive as the fibers can store a lot of energy from the combination of strength and elasticity, but the composite can accumulate damage with even the smallest loads, a characteristic shared with aluminum.
For much more about composite fatigue failure than is suitable to type here see Principal Features of Fatigue and Residual Strength of Composite Materials Subjected to Constant Amplitude (CA) Loading, section 2.5. The Hierarchy of Damage. It's an NIH report and mostly technical, but the 2.5 section gives a good overview.
**I have seen metal parts that failed in use where more than 90% of the original material had succumbed to the fatigue crack and only 10% or less remained to be twisted loose; a load that was very small compared to the strength capacity of the undamaged part.
Maybe you are talented and knowing people - is it worth to open a separate special thread on this composite fuselage - shimming issue to take a detailed look? I could jump start by collecting relevant infos, but I need to stay out of technical conclusions.
WR 6-3, always interesting to see your views and excellent assessments! 
I guess my only thought on this is that we really have 2 questions here:-
(1) Has the use of these practice on the joints caused a safety issue with the affected airframes? Maybe not - an engineering decision required there but it seems Boeing (and others) think not.
The other arguably more important question is:-
(2) Was this technique an approved, formally safety assessed method of build documented by Boeing? Well, I think the answer is "no". This being the case, how many other non-documented, non-approved practices are taking place across all the company assembly lines? This latter point links nicely with the Alaska Airlines Flight 1282 where it increasing looks like poor/undocumented work (for possibly a number of reasons) took place leading to the loss of the door plug in flight.
So, Boeing may be able to "prove" (1) is not an issue ....... but, in many ways, (2) is the far more serious question. Answering that one will be exceedingly difficult for Boeing to prove. And I'm sure other manufacturers will be using this as an opportunity to look critically at their own production lines. This last point is a very positive spin-off from Boeing's woes.
Anyway, just a thought........
I guess my only thought on this is that we really have 2 questions here:-(1) Has the use of these practice on the joints caused a safety issue with the affected airframes? Maybe not - an engineering decision required there but it seems Boeing (and others) think not.
The other arguably more important question is:-
(2) Was this technique an approved, formally safety assessed method of build documented by Boeing? Well, I think the answer is "no". This being the case, how many other non-documented, non-approved practices are taking place across all the company assembly lines? This latter point links nicely with the Alaska Airlines Flight 1282 where it increasing looks like poor/undocumented work (for possibly a number of reasons) took place leading to the loss of the door plug in flight.
So, Boeing may be able to "prove" (1) is not an issue ....... but, in many ways, (2) is the far more serious question. Answering that one will be exceedingly difficult for Boeing to prove. And I'm sure other manufacturers will be using this as an opportunity to look critically at their own production lines. This last point is a very positive spin-off from Boeing's woes.
Anyway, just a thought........
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While the technical issue appears to have had a thorough and satisfactory engineering assessment, the cultural aspects remain unanswered. Per Hudson, Reason et al, trust must be in place before effective communication takes place. Had the whistleblower trusted that his concerns would be addressed through company channels, it is unlikely to have been escalated to a Congressional Hearing. The 103 report indicates that there is Management/worker diconnect on safety culture, SMS and safety initiatives.
I was in AMS yesterday. On the stand beside us was a KLM 787-10, which is probably less than 3 years old. As I was doing the walkaround of my airplane, I noticed the sun reflecting off the blue color on the upper fuselage. And the fuelage surface looked pretty uneven all over. More so than with any aluminum airplane. Also the fuselage join where the AFT (Section 47) meets the MID (section 46) was really well noticeable. Something I have not noticed on other airplanes. Seems to my pilot eye, the Boeing method of making composite fuselages does not lend itself to making super even and smooth surfaces.
I have no idea whether I would see the same on an A350…
I have no idea whether I would see the same on an A350…
Was the fatigue testing done on a fuselage with the specific fault ? That is one with the excessive gaps present?
The fatigue characteristics of riveted aluminum structures are very well understood, however all composite structures are quite new. I would be interested in hearing from a structures expert on how well these types of structures resistance to degradation can be evaluated.
The fatigue characteristics of riveted aluminum structures are very well understood, however all composite structures are quite new. I would be interested in hearing from a structures expert on how well these types of structures resistance to degradation can be evaluated.
Deliberate deviation from drawing during manufacture, fitting, assembly, which obviously would include use of excessive force, missing/incorrect size shims, takes the component or structure into unknown territory and not covered by the pre-certification testing.
Last edited by Commander Taco; 28th Apr 2024 at 01:46.
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That forms the basis of the whistleblowers allegations. As a post-production engineer with responsibility to ensure that the finished product meets both the pre-production build and the pre-production certified standard, he alleges that the aircraft do not meet those requirements.
FAA presumably will reply to the letter filed by Mr Salehpour's attorneys. But until then . . .
Also given the content of various posts following the one in which I summarized the AW&ST article, the refusal to release the documents that were filed with FAA together with the attorney's letter now seems even more difficult to understand. The predicate for the hearing before the Senate Permanent Subcommittee on Investigations - where the whistleblower testified - was that (paraphrasing) the American people have a right and/or need to know if these airplanes are safe. On what basis are the American people being told to ponder this question with only part of the relevant information? Is it because once FAA completes its review, the entire filing will be made public?
This would ordinarily be handled by going to the FAA first, but it will probably go there next. I know from aircraft radar development projects I was on, there was no way to afford to test every extreme tolerance excursion, but everything had a factor of safety; the main structure was capable of resisting 30 Gs and then some for margin.
The question bridges between if it met the certified configuration and if the deviations were run through engineering to confirm the result would meet the original requirement. Either should be acceptable.
The question bridges between if it met the certified configuration and if the deviations were run through engineering to confirm the result would meet the original requirement. Either should be acceptable.
EDIT: I found it. Not sure if I interpret it right. See in there:
Last edited by waito; 28th Apr 2024 at 09:09.
This would ordinarily be handled by going to the FAA first, but it will probably go there next. I know from aircraft radar development projects I was on, there was no way to afford to test every extreme tolerance excursion, but everything had a factor of safety; the main structure was capable of resisting 30 Gs and then some for margin..