In the previous post, I described the response to the Comet jet crash.
This has become quite long, but I've tried to reconsider the causes of the Comet crash, from its planning stages to the response to the accident.
Looking back, what is generally saidI hope you now understand that stress concentration and fatigue failure in the pressurized chamber are not the only causes.
This time, let's deliberately move away from engineering issues and consider the lessons we can learn from the Comet jet crash.
Lessons learned from the Comet jet crash
To begin with, recalling the planning stages, the British government began considering the idea of operating private jet aircraft in order to seize dominance in the post-war aviation industry.
The important points are:The desire to start operating jet aircraft as quickly as possible was to dominate the civil aviation market.Let's watch it while keeping that in mind.
Planning
Based on that concept, the government envisioned four types of jet aircraft, and commissioned the development and manufacturing company (de Havilland) to create a high-speed transatlantic mail jet transport aircraft known as Type 4.
However, the development and manufacturing company (de Havilland) inexplicably proposed a large four-engine jet passenger aircraft (later known as the Comet), and the British government readily withdrew its own plan and accepted the proposal.
The government's decisions here are already quite bad.
No matter how well-established the theory behind a technology may be, it cannot be realized without careful consideration and verification step by step.'S.
The government at the time probably understood this, which is why they initially considered developing high-speed mail transport aircraft in order to gradually accumulate technology, but I think they ended up being swayed by the attractive proposals of the development and manufacturing companies.
I believe this was one of the turning points and the first step that led to the tragedy of Comet.
In other words, No matter how tempting the offer, I believe it's important to look at reality and make a calm judgment (a lesson learned).
If you let greed blind you and make the wrong judgment, you'll suffer painful consequences later.
In any case, development will begin once the government places an order for a large four-engine jet passenger aircraft.
This is just my speculation,I think the most challenging condition in this development was the extremely short deadline set by the government.
It is highly likely that they placed an order for a large four-engine jet passenger aircraft with the same delivery date as the initial Plan 4, which involved a high-speed transatlantic mail jet transport aircraft.
In other words, the deadline remained the same, but the development difficulty became far more challenging compared to Plan 4.
Despite the nature of the project, I believe the development and manufacturing company accepted the tight deadline because of the enormous profits and prestige that would result if they succeeded.
This is another crucial point: the development and manufacturing companies have lost their composure and are misjudging the time required to bring the project to fruition.
Both the government and the development and manufacturing companies have lost their composure, and the situation is extremely dangerous.The government (the client) is supposed to be the oversight body for the development and manufacturing company, but I believe that the normal relationship had already broken down at this stage.
Based on this situation, let's review the concept behind Comet.
concept
At this conceptual stage, a significant amount of time would normally be spent examining phenomena in unfamiliar technological areas and researching solutions to technical challenges. However, due to the extremely limited time available for realizing a civilian jet aircraft, there wasn't enough time for this.
In particular, the jet engine and pressurized chamber, which are crucial technological elements of the Comet, were already established individually, so it seems that the team thought there were few unknown technological areas (combined new technologies).
This is also an important point.Even today, it's quite common for known technologies, when combined, to venture into uncharted territory (a lesson learned).
This pattern isEven today, we often see hidden, unknown areas emerging in the market, leading to malfunctions and accidents (similar to the Comet).
Engineers need the observational skills, perspective, and creativity to discover hidden, unknown areas.That is very important.
Next, let's take a quick look back at the process from design to test flight, which all share common problems.
The entire development of Comet
To state the conclusion first, in every aspect of development, all of the crucial systems of the development and manufacturing company—including development systems, checking functions, and management structures—had collapsed.
Looking at the details, there are many questions, such as whether technical challenges were shared throughout the company during the design phase, and whether test content and results data were shared throughout the company during testing.
The stress concentration and fatigue fracture that caused the accident were known to some extent at the time, yet they were largely overlooked. This suggests that the development process was extremely sloppy.
It's impossible that all of the many elite engineers working for the huge and prestigious development and manufacturing company (de Havilland), which fought through the great war, were unaware of this problem.
It's likely that several engineers pointed out safety concerns, but ultimately, those concerns weren't reflected in the development process.
このI think one of the main reasons was that the development time was considerably shorter than the content required.
I feel this way in particular because of the production method of the pressurized chamber, which involves dividing it into sections and gluing them together to complete it. This method prioritizes how quickly a massive pressurized chamber can be produced over functionality, performance, durability, or safety.
This divided approach eliminates the problems of constructing new factories and developing new construction methods.
The adoption of this production method meant that Comet itself was venturing into uncharted territory, and the testing method also entered uncharted territory (finite element method).
Furthermore, the fact that they used the same parts in both the destructive test and the fatigue test suggests a considerable lack of time and a sense of urgency in development (something that would never have been done even before the war).
The insufficient testing of the aircraft is another example of this.
このThe lack of time and the resulting panic destroyed a normal development system, checking functions, and management structure.
またThis lack of time has not only affected the development and manufacturing companies, but also disrupted the normal functioning of the government.
Important things you can learn from thisThe lesson learned is that even in extremely difficult situations, such as having very little time, it is crucial for engineers to remain calm and approach their work with an honest perspective..
Furthermore, even under the most extreme conditions, the development systems, checking functions, and management structures built upon accumulated experience must be maintained at a certain level.
If you do make any changes, you need to think carefully and take precautions to ensure that nothing is overlooked, otherwise things could go very wrong.
Furthermore, when venturing into uncharted territory like with Comet, there will inevitably be aspects that cannot be fully assessed through existing tests and checks alone. Therefore, if development is not carried out with careful consideration, it can lead to serious problems later on.
ThereforeThe author strongly recommends allocating time and establishing a specialized organization to consider new issues, countermeasures, and verification test content that may arise in areas beyond the usual test content and checklist (a lesson learned).
At least back then, if development had been conducted under normal conditions, discovering the stress concentration and fatigue fracture that caused the Comet crash during development would not have been that difficult.
Finally, let's review how we handled the accident.
Accident response
As I mentioned last time, the response to the accident was among the worst in history.
As many people have probably already realized, even before the accident, the government and the development and manufacturing company were no longer able to view the Comet with a calm and honest eye, and their actions after the accident have been completely rigid and ineffective (they haven't even been able to conduct a proper investigation).
Fortunately, a great historical figure, Prime Minister Churchill, made a crucial decision at the time, allowing the RAE, a third party, to investigate the cause of the accident.
No longer like thisOrganizations and groups that have fallen into a state of rigidity often lose their ability to correct themselves, and unfortunately, historically, they often end up either relying on external forces or collapsing.
This is something that has often been seen in large Japanese companies over the past 20 years or so. A certain prestigious automobile company was acquired by a foreign company, a food company that was involved in a scandal went bankrupt, and the country's largest airline somehow managed to recover with the help of the Industrial Revitalization Corporation.
The important thing is how to calmly assess oneself before the organization becomes rigid, and to continue to change and evolve as needed.There is only one.
The true lesson, in my opinion
Up to this point, I have argued that the Comet crash not only presented engineering problems such as stress concentration and fatigue failure, but also highlighted significant problems and lessons regarding the lack of composure in the judgments and actions of the government and the development and manufacturing company, as well as issues within various organizations, development systems, checks and balances, management systems, and operations.
The British government at the time likely conducted a thorough analysis, examining not only the engineering issues but also organizational problems, gaining expertise, and taking appropriate action.
In Japan, the only issues that have been reported regarding the Comet plane crash are basically stress concentration and fatigue failure. I believe this is because the British government has not made public the crucial aspects of its approach to developing uncharted territory and its organizational management.
It's a bit of a conspiracy theory and not really my cup of tea, but the truth is, truly valuable know-how is rarely leaked to outsiders, whether by a government or a corporation.
This is purely my personal opinion, but surprisingly, America is quite laid-back, and if you look around, you can find valuable know-how written or taught in various places.
I, too, spent about three years at my company researching development methods in unfamiliar areas and efficient development methods, studying and trying to implement individual methods such as popular requirements development, agile methodologies, and systems engineering, as well as idea generation methods like design thinking.
While I could discuss what development systems would have been optimal for Comet based on that research, the era, organization, and background are quite different from those at the time, so I don't think there's much point in discussing it further. Therefore, I will omit that section.
Furthermore, the optimal approach will vary depending on the size, culture, and mindset of the organization, as well as the target product, so I don't think it's very meaningful to consider it in terms of a single case, and I'll stop there.
In any case, the Comet project had many problems beyond just engineering.
As I mentioned beforeI believe the true lesson of the Comet jet crash is that when considering the cause of an accident, we should look at the event from multiple perspectives, not just the single engineering viewpoint of stress concentration and fatigue failure.
While it's true that machine accidents and malfunctions always stem from engineering problems, the crucial question is: why did such engineering problems occur? Why weren't they detected in pre-testing? Why were they overlooked? Why were they missed in the numerous checks? Thinking about these underlying mechanisms is extremely important.
If the only lessons learned from the Comet incident were stress concentration and fatigue failure, then creating a checklist might prevent the same phenomenon from happening again. However, if other parts of the mechanism remain unchanged, then when faced with new challenges, similar mistakes will inevitably be repeated.
SoThe important lesson from this accident is that any problem should be viewed from multiple perspectives; ideally, it shouldn't just be seen and considered by engineers, but by people from many different fields.
When an accident like this occurs, the absolute worst thing you can do is dismiss it as being due to a single, simplistic, and blaming-based cause, such as the person in charge being incompetent, it being an irregular situation, simply not knowing, or a check being missed.
Taking such measures would be tantamount to leaving the factors that will inevitably lead to a major accident like the Comet sooner or later.
Especially in modern times, scientific and technological advancements are progressing by leaps and bounds, and there is no doubt that the pace of human exploration and development is accelerating.
If that happens, the number of times we venture into uncharted territory, like with Comet, will naturally increase.
If we rely solely on simple responses to failures and accidents, or on engineering alone, to address this, we will absolutely not be able to cope, and the probability of even more irreversible major accidents occurring will be considerably higher.
That's whyWhile it's natural for companies and organizations to work on improving and evolving their operational methods, organizational structures, and development systems, I believe that significant progress will be difficult unless we all, including the government, continuously think about and evolve ways to address these issues through the entire social system.
The Comet failure and accident teach us a crucial lesson: preventing future major accidents requires considering not only engineering issues, but also the entire societal structure, including corporate and government management, organizational structures, and development systems.I think that's what will happen.
Afterword
Initially, I intended to write about the lessons to be learned from this Comet crash solely to explain the importance of fatigue fracture in materials mechanics, which I've discussed in this blog.
The Comet jet crash left a strong impression on me as a problem of stress concentration and fatigue fracture, which I learned about during my student days, so I thought it would be a good way to conclude my study of mechanics of materials.
However, having gained some experience in engine design and development methodology research at my company, looking at the Comet accident again, stress concentration and fatigue failure, while important, now seem like minor issues, and there appears to be a more important and crucial cause.
So, I changed my original objective and started writing about my thoughts based on my own experiences, which ended up being close to 14 characters in total.
Upon investigation, it turned out to be a larger volume of text than a typical paperback book.
I'm just a mechanical designer and not a writer, so this was my first time writing a series of this length of text, and I struggled quite a bit along the way, but I managed to finish it.
I'm very worried about how many people will actually read this far (maybe none at all), but I've written what I wanted to write, so I guess that's good enough.
This might seem inappropriate to include in an afterword, but after researching this accident, I was reminded once again that we need to look at things from a more multifaceted perspective.
As someone who is a technologist, engineer, and designer, I used to have a tendency to be less interested in anything other than engineering issues, and I'm reflecting on that now.
I suspect that most of the people reading this are in the engineering field, but I would really like people from completely unrelated fields to read it as well.
I also hope that this message will reach people in engineering fields, reminding them that malfunctions and accidents shouldn't be prevented solely through technology, but also through mechanisms and systems.
To those who found this article helpful in understanding design:
Since we're on the subject, I'd like to recommend a book that's essential for mechanical design.
To be honest, the content is extremely unhelpful, but it can be used like a dictionary when you forget the details. If you read this article, you should be able to understand the content and use it effectively. It also includes commonly used standards, making it quite useful.
If you don't already own one, I highly recommend getting one, even though it's a bit pricey. However, new ones are expensive, so if you're considering buying a used one, I strongly recommend checking that the surface roughness conforms to the new JIS standard.
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