So good this analysis.Quote:
Originally Posted by BradC
https://youtu.be/UpUkwzVUs5Y?si=vCY8eEr6AIDe4S9X
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So good this analysis.Quote:
Originally Posted by BradC
https://youtu.be/UpUkwzVUs5Y?si=vCY8eEr6AIDe4S9X
From what we have seen so far, this has to be one of the best documented aviation accidents ever - really good footage of the accident from multiple viewpoints, both recorders found and producing good data, lots of witnesses, accident site controlled immediately, and the key point on open but secure ground allowing rapid and skilful collection of data on the engine departure..
And from the rapid publication of the preliminary report, the NTSB is doing a good job of analysing the data. But because of the amount of data, I expect it will take a long time to get to the final report and decide what caused the fatigue cracks to appear before the next inspection was due. Always assuming the previous inspection was completed correctly, something that may take a good while to determine.
I assume that there will be inspections of the pylon mounts on all of these aircraft before they allow them to fly again, and it will be interesting to see if any fatigue cracks are detected. I assume inspections will be using a penetrant dye since the mounting lug that broke is non-magnetic.
The only thing that would make things easier is having a wreck to examine. The fire just complicates the investigation. At least most of the pylon left with the #1 engine so it can be accurately examined.
They seem to have recovered the brackets that the pylon was attached to from the wreckage and the bits that broke off, apparently from the pylon, both intact enough to see the fatigue cracks, which show up distinctively on the fracture surface (see the pictures in the video).
I think that the type is down to 82 examples might play into it. They will have more time to consider the issue, and the low volume of AC that are nearing retirement might affect the fix too. Hopefully will just be a change to inspection schedule but if it requires expensive changes then it might not be worth it in many cases.Quote:
Originally Posted by JDNSW
The number of hours and cycles the airframes have done will be a big influence as well. I'm certain that Boeing can come up with a new inspection schedule, but any modifications to the structure would probably tip the scales of a cost/benefit analysis. Not cheap to re-engineer and refit 82 of them.Quote:
Originally Posted by Captain_Rightfoot
Of course, foreign carriers can do their own thing, but the countries they can fly to will sure be restricted.
Theres a type of induction testing that works with ally and alloys but IIRC it doesnt give a very precise result and is kind of a go/no go test to negate or approve the requirement for more expensive/invasive testing.Quote:
Originally Posted by JDNSW
Whichever method they choose Id really love to see a 3d rendered model and some cutaways done that showcase the crack(S) through the depth of the pylon.
Id also be interested to see if a "ringing test" might have revealed anything. Effectively hang it from a bit of wire and tap it with a hammer, solid relaxed metals resonate differently to ones with internal stresses and fractures. Put a good one up next to a failed one and give them both a love touch with a suitable mallet..
Nevil Shute, author and aeronautical engineer, wrote about fatigue failures in structural alloys in 1948. One would hope they have moved on a little from then...
More precisely, Neville Shute Norway, when he was wearing his engineers hat.
He started his career as an aeronautical engineer after a brief stint at De Havilland, doing stress analysis on the Airship Guarantee Company's (Vickers) R100 airship in 1924-1929. The R100 was quite successful, and did a return trip across the Atlantic without significant incidents. However, its competitor, the R101, built by the British government, on its maiden flight to New Delhi, crashed in France with few survivors. This led to the grounding of R100, and it was scrapped shortly afterwards.
Norway then founded the Airspeed Ltd to build advanced civil aircraft and a few years later started producing the Airspeed Courier single engine retractable, and later the Envoy, a twin. Having picked a bad time to start (Great Depression), by 1940 the company was taken over by De Havilland, and produced a large number of the twin as the Oxford trainer for the RAF.
He thought that both Vickers and the directors of Airspeed would be less than thrilled by having him a published author (starting 1926), so he only used his first two names for his writing.
True, John, but I know him from his novels, although I have read Slide Rule several times. He was scathing of the Air Ministry's handling of the whole R101 project. He said that they cost those lives due to their bureaucratic bungling and interference.
I highly recommend Slide Rule to those who are interested. Brilliant autobiographic work written by a true story teller.
He has a street named after him in Berwick. I guess Lord Casey had something to do with that. Nevil loved Australia.