Easy slips in AMS ?
Join Date: Sep 2003
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Angels: Not an unreasonable question, so nothing needs to be apologised for.
As to the extent of damage... well, keep in mind Sir Isaac's work... force equals mass times velocity. There's an appreciable amount of mass, even if the velocity was not that great.
What made it worse is that it hit a wing and caused serious damage to the wing spar, apparently.
The wing spar is basically a very similar version of a boat's (hull) ribs, and wrapped with a thin covering of sheet metal. The metal is pretty darned thin for reasons of saving weight, and protected by decree -- people are not allowed to walk anywhere they want on the wings, only on a very specific area if absolutely necessary (and is designed for the loads there).
Next time you take a flight with a window seat by the wings, you may see a spray-painted wording near where it attaches to the fuselage that says (to the effect of) "Do NOT walk on wing past this point". General aviation planes have similar restrictions for the low-wing planes where you need to walk on a narrow portion of it to get in or out of the cockpit.
(Saving weight translates to greater distance [range], greater cargo carrying or passenger carrying capabilities, possibly cheaper engines, lower overall aircraft cost, etc.)
To the average SLF, the fuselage is the most important piece of a plane. To me, the wing is probably it because it is a major load-bearing structural element, stores an appreciable amount of fuel, and generates pressure differentials across aerodynamic surfaces that makes flight possible. You can recover from a number of extreme situations, but lose a wing, ouch.
A wing is extremely strong and can support an incredible amount of load, but it's got to be done right to do that.
There's also concern when you damage a major structural member -- be it a car's frame or a plane's wing, that there's a tiny chance the repair might not fully address all of the damage or introduce unseen problems that could result in a future tragedy. All said, I'd imagine a repair of that nature would be sent back to the aircraft manufacturer for total replacement (of a wing in this case)... which is not particularly cheap if done after the initial build.
The way insurance typically works with airliners is... if the cost of repair is below a threshold (typically about 70% of the cost of a new plane of same make/model?), they will repair it and put it back in operation.
There has been a number of planes with ugly and pretty darned extensive damage from major incidents, but were fixed up and very quietly put back in service.
If the repair cost exceeds the threshold, the insurance company considers it a total loss, pays out to the airline, takes possession of the busted plane, and conducts its own investigation.
Reason? They want to make sure it isn't some sort of training or SOP deficiency with the carrier -- if it is, they can mandate changes be made to reduce the likelihood of losing another plane, and the subsequent financial impact.
But in this case, it doesn't seem the carrier or flight crew is at fault. Open question on if airport is at fault or responsible for any portion of the cost recovery. It will be interesting to see how the various parties ultimately concludes the financial end of it.
As a side note, someone posted (earlier in this thread) a link to airliners.net posting of a photo that reportedly showed the damage to the wing spar. I'd hoped to point it your way to better appreciate a wing spar's internal structure, but appears that photograph may have been yanked.
A wing may resemble something like this internally:
http://pages.cfu.net/~peacock/wetwing.htm
As to the extent of damage... well, keep in mind Sir Isaac's work... force equals mass times velocity. There's an appreciable amount of mass, even if the velocity was not that great.
What made it worse is that it hit a wing and caused serious damage to the wing spar, apparently.
The wing spar is basically a very similar version of a boat's (hull) ribs, and wrapped with a thin covering of sheet metal. The metal is pretty darned thin for reasons of saving weight, and protected by decree -- people are not allowed to walk anywhere they want on the wings, only on a very specific area if absolutely necessary (and is designed for the loads there).
Next time you take a flight with a window seat by the wings, you may see a spray-painted wording near where it attaches to the fuselage that says (to the effect of) "Do NOT walk on wing past this point". General aviation planes have similar restrictions for the low-wing planes where you need to walk on a narrow portion of it to get in or out of the cockpit.
(Saving weight translates to greater distance [range], greater cargo carrying or passenger carrying capabilities, possibly cheaper engines, lower overall aircraft cost, etc.)
To the average SLF, the fuselage is the most important piece of a plane. To me, the wing is probably it because it is a major load-bearing structural element, stores an appreciable amount of fuel, and generates pressure differentials across aerodynamic surfaces that makes flight possible. You can recover from a number of extreme situations, but lose a wing, ouch.
A wing is extremely strong and can support an incredible amount of load, but it's got to be done right to do that.
There's also concern when you damage a major structural member -- be it a car's frame or a plane's wing, that there's a tiny chance the repair might not fully address all of the damage or introduce unseen problems that could result in a future tragedy. All said, I'd imagine a repair of that nature would be sent back to the aircraft manufacturer for total replacement (of a wing in this case)... which is not particularly cheap if done after the initial build.
The way insurance typically works with airliners is... if the cost of repair is below a threshold (typically about 70% of the cost of a new plane of same make/model?), they will repair it and put it back in operation.
There has been a number of planes with ugly and pretty darned extensive damage from major incidents, but were fixed up and very quietly put back in service.
If the repair cost exceeds the threshold, the insurance company considers it a total loss, pays out to the airline, takes possession of the busted plane, and conducts its own investigation.
Reason? They want to make sure it isn't some sort of training or SOP deficiency with the carrier -- if it is, they can mandate changes be made to reduce the likelihood of losing another plane, and the subsequent financial impact.
But in this case, it doesn't seem the carrier or flight crew is at fault. Open question on if airport is at fault or responsible for any portion of the cost recovery. It will be interesting to see how the various parties ultimately concludes the financial end of it.
As a side note, someone posted (earlier in this thread) a link to airliners.net posting of a photo that reportedly showed the damage to the wing spar. I'd hoped to point it your way to better appreciate a wing spar's internal structure, but appears that photograph may have been yanked.
A wing may resemble something like this internally:
http://pages.cfu.net/~peacock/wetwing.htm
FX Guru
Join Date: Feb 2001
Location: Greenwich
Age: 67
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Luv 744s - Many thanks for your thorough explanation, I really appreciate it.
My first ever long haul (blimey 25 years ago now, sigh) was with TG to BKK from LHR and we had pretty bad turbulence for half the trip. I remember just focusing on the wing to my left -- okay port) and saw the give it had.
I truly realised then what a wonderful piece of engineering an aircraft is.
Again, my thanks.
My first ever long haul (blimey 25 years ago now, sigh) was with TG to BKK from LHR and we had pretty bad turbulence for half the trip. I remember just focusing on the wing to my left -- okay port) and saw the give it had.
I truly realised then what a wonderful piece of engineering an aircraft is.
Again, my thanks.
