Todos
← Back to Squawk list
Boeing’s 777X Fuselage Was Ripped Apart During Pressure Testing
New images have surfaced of what really happened during the September pressure testing of Boeing’s new 777X aircraft. September’s pressure test was widely reported to have failed, with a cargo door being blamed for the issue. Now, it seems that the situation was a lot more serious than that. The news that a cargo door had blown off the 777X during its stress test in September was shocking enough. However, it now appears that the situation was far worse than we could ever have imagined. According… (www.seattletimes.com) Más...Sort type: [Top] [Newest]
As much as this article "seems" to be "negative", I see this as a "positive" for the design. The negative - the structure failed just below the 1.5X limit load - the positive - this thing was instrumented out the ass so the engineers have plenty of data to make the appropriate design changes to finish off the certification "by analysis".
Let us remember that 1.5 is an arbitrary, reasonable number established by humans with experience and education in their respective field. We could make it 2.0 have cost the flying public millions, if not billions, of dollars because of the added weight of the structure, or we could go the other way, and be closer to potential loss of life. Yes, sometimes judgements regarding other factors like $ get in the way of those numbers, but in general those numbers (like 1.5) have proven their worth as a good balance of safety factors, engineering costs, manufacturing costs, and economics.
For example: When the 747 did a qualifying evacuation using an average cross-section of population including elderly, adults, children, physically challenged, etc., one of the requirements was that half of the exits (there were a total of 10 on the -100 model)had to be rendered inoperative, and which ones were inoperative were not known to the flight attendants onboard. The evacuation had to be completed in 90 seconds. As it turned out, one of the "good" doors actually failed, in addition to the planned 5, and the evacuation using 4 doors actually took 107 seconds.
The judgement of the regulators, engineers, airline executives and observing crew members was that the evacuation was successful and the aircraft type met its certification requirements in that area. As far as I know, in all of the actual emergencies requiring evacuation, that 107 seconds was never an issue.
Point is, the difference of 1%, is going to be dealt with by knowledgeable people who also will end up flying some day on the 777X, and I for one will trust their judgement, as I do on things, like the make up of Minimum Equipment List, or Maximum Crosswind Component for landing, etc. Once the issue is addressed, I'm OK with that and will be OK to fly on the 777X,as far as structural integrity is concerned.
For example: When the 747 did a qualifying evacuation using an average cross-section of population including elderly, adults, children, physically challenged, etc., one of the requirements was that half of the exits (there were a total of 10 on the -100 model)had to be rendered inoperative, and which ones were inoperative were not known to the flight attendants onboard. The evacuation had to be completed in 90 seconds. As it turned out, one of the "good" doors actually failed, in addition to the planned 5, and the evacuation using 4 doors actually took 107 seconds.
The judgement of the regulators, engineers, airline executives and observing crew members was that the evacuation was successful and the aircraft type met its certification requirements in that area. As far as I know, in all of the actual emergencies requiring evacuation, that 107 seconds was never an issue.
Point is, the difference of 1%, is going to be dealt with by knowledgeable people who also will end up flying some day on the 777X, and I for one will trust their judgement, as I do on things, like the make up of Minimum Equipment List, or Maximum Crosswind Component for landing, etc. Once the issue is addressed, I'm OK with that and will be OK to fly on the 777X,as far as structural integrity is concerned.
Counterpoint: you should never reduce your safety margins reactively.
When you are flying, for example, if your personal self-enforced maximum crosswind component is 10 knots, you shouldn't decide 11 is okay because when you check the forecast before takeoff it looks a bit "marginal". You should sit it out. Then, on a nice calm day with a 3-knot crosswind you can think about whether it's safe to increase your personal maximum given your increased experience and knowledge.
Also, if my maximum allowable takeoff weight is 2000 lbs, I know darn well that my airplane can handle 2001 pounds, but I still limit it to 2000 because that's the threshold and if 2001 pounds is okay, why not 2002? I'm not starting on that slippery slope.
When you are flying, for example, if your personal self-enforced maximum crosswind component is 10 knots, you shouldn't decide 11 is okay because when you check the forecast before takeoff it looks a bit "marginal". You should sit it out. Then, on a nice calm day with a 3-knot crosswind you can think about whether it's safe to increase your personal maximum given your increased experience and knowledge.
Also, if my maximum allowable takeoff weight is 2000 lbs, I know darn well that my airplane can handle 2001 pounds, but I still limit it to 2000 because that's the threshold and if 2001 pounds is okay, why not 2002? I'm not starting on that slippery slope.
Well said.
It's good to test them to the maximum so that only the very unexpected will make them crash.
It's good to test them to the maximum so that only the very unexpected will make them crash.
The source article in the Seattle Times:
https://www.seattletimes.com/business/boeing-aerospace/boeing-777xs-fuselage-split-dramatically-during-september-stress-test/
https://www.seattletimes.com/business/boeing-aerospace/boeing-777xs-fuselage-split-dramatically-during-september-stress-test/
[This comment has been downvoted. Show anyway.]
It matters because with modern design and engineering methods, the fuselage is tested virtually long before it is ever constructed as a test article -- physical testing is merely used to validate.
If the test wasn't meant to be destructive, it points to a design or manufacturing defect.
If the test wasn't meant to be destructive, it points to a design or manufacturing defect.
Here you go with your negative comments. Can't you say something positive?
I was not replying to Torsten's comment. It was linbb. I totally agree with Torsten's comment.