[dropkic]

Originally Posted by Hunted ↗

Video from inside the jet & after.

Will somebody slap that bitch! STFU!

[William May]

Originally Posted by durt ↗

Those engines, that's odd??

On airlines, the engines are held on with fuse pins, that shear at a certain maximum load.

Not as dramatic as it sounds. Many years ago, a 727 showed an engine failure, so the crew shut it down. When they got to their destination airport and the crew got out to see what was going on, the engine was missing. Apparently they had a lav leak, it formed a large chunk of blue ice on the side of the aircraft, and when it came loose, it went into the engine. The forces involved were enough to break the shear pins, and the engine fell away. They found the engine and on examination they found the residue from the blue ice.
The crew reported they felt no difference in flight characteristics, didn't feel the engine depart the aircraft, and said if they had been aware of it, they would have declared an emergency. But since all they had was a shut-down engine, they just proceeded per the checklists and flew to their destination. The passengers never noticed anything at all.
When the engine is shut down, it shuts off all fuel and hydraulics, and all electrical to and from the engine. The separation points are designed to give a clean breakaway, (Usually the hoses are the break points, and they just tear off) so an engine loss doesn't introduce a chain reaction of catastrophy.
The landing gear has those pins as well. They are designed so the gear either goes over or under the wings. On the 737, the engines were hinged by pins with various breaking points, so the engine would lift and somersault up over the top of the wing, and disappear. The gear was pinned so it would fail backwards and disappear. I don't know about the 727, but I imagine since it was a T- tail aircraft, the engines were pinned such that they broke the front mount pins first, the engine nose dropped, and then the rear pins sheared, and the engine dropped away cleanly.
Anyway, it worked as advertised.
When an aircraft lands, ALL the energy you see in the crash pictures is absorbed by the braking system. EVERY landing has enough energy to shred the aircraft and all it's occupants.
This is what engineering is. It's making sure all that energy is channeled correctly, and you ride to a gentle stop at the end of the runway. But the available energy was the SAME on your peaceful landing that it would be on the crash pictures you see on here.
But if there WAS an accident, a lot of that energy is absorbed by those pins. It takes energy to break them, and that energy is used up as they fail. By tearing off the landing gear and the engines, you expend the energy that would be available to tear arms and legs off of people. Like the crumple zones on a Volvo, the idea is to use as much energy as possible, doing other damage, so as to shield the human occupants of the machine.
I will use a very basic example.
Say you have 100 ergs of energy in an aircraft landing. Engineers have calculated that 70 ergs are enough to kill everyone on board. But if each landing gear absorbs 10 ergs of energy, then the loss of the landing gear puts you at the borderline of survival. If each engine also absorbs 10 ergs, then you have now dropped the available energy for killing the passengers from 70, down to 50 ergs left. If the collapse of the wings takes another 20 ergs, you are now down to 30 ergs, and you have an event that is now classed as surviveable. If the fuselage crumples at the bottom as it slides along the ground, and you absorb another 20 ergs, then you are now down to 10 ergs. Distributed through the passenger cabin. it means everyone is shaken up, but they all survive. There will always be the unlucky few, who unbelted themselves, and so died as they became flying missiles in the cabin. Or the one or two who got hit by flying debris, or were unable to escape the fire, etc. But when you see the film of everyone climbing off the aircraft and standing by the side of the runway while the fire trucks and emergency people race around, you are witnessing designed energy management in action.

[William May]

Originally Posted by Dildo_Faggins ↗

THAT'S WHY I WILL NEVER FLY.

I guarantee you, that your greatest danger in flying is on your road trip to the airport.
If flying was as safe as automobiles, we would be crashing a fully loaded 747 EVERY DAY.
Flying has never been safer. It is the safest form of movement on the planet.
(Also, the people who survived this, have won the aviation lottery. To be involved in a SINGLE incident in aviation is so rare it's like winning the lottery. The odds of being involved in a SECOND incident are virtually infinitesimal. These people can fly again for the rest of their lives, and they will NEVER be involved in another aviation incident. If they got on an airplane missing one wing, and with one engine on fire, they would STILL arrive safely at their destination.)

[Clubhouse]

Didn't read the post above, I was going to say pretty much the same thing

WM do you use the forum below?


https://www.pprune.org/

[William May]

Originally Posted by Clubhouse ↗

Didn't read the post above, I was going to say pretty much the same thing

WM do you use the forum below?


https://www.pprune.org/

No, I have never seen it. I am on a mechanics forum. But now I have seen that, I will have to check it out, it looks very interesting.
My erg numbers are just filler. I have no idea how much energy there really is in an accident, it would depend on the total weight and the total speed at impact, however, the development of the idea IS correct. I just picked round numbers to make it less mind-numbing and to keep it brief. I have often inspected the shear pins on both the engines and the landing gear on 737's, I wish I had taken a picture of them when I was around them. A picture is worth 1000 words, like they say.
I do know that the 737-300 (and I assume all the 737's equipped with the CFM 56 and it's relatives) had the pins designed so the engine would back-flip over the top of the wing in an accident. I heard that from a Boeing engineer who was at our facility supervising the repair of one that had dragged it's tail on takeoff, and damaged the skin joint right at the pressure vessel joint line.

[Analcuck]

Originally Posted by William May ↗

I guarantee you, that your greatest danger in flying is on your road trip to the airport.
If flying was as safe as automobiles, we would be crashing a fully loaded 747 EVERY DAY.
Flying has never been safer. It is the safest form of movement on the planet.
(Also, the people who survived this, have won the aviation lottery. To be involved in a SINGLE incident in aviation is so rare it's like winning the lottery. The odds of being involved in a SECOND incident are virtually infinitesimal. These people can fly again for the rest of their lives, and they will NEVER be involved in another aviation incident. If they got on an airplane missing one wing, and with one engine on fire, they would STILL arrive safely at their destination.)

I've got weird luck. I know I'm thousands of times less likely to die on a plane, but some fears exist for a reason. It only takes one time to be the unlucky bastard who beats the odds - I've probably just watched too many death and crash videos, but it's not an irrational fear then, it's a reasonable fear based on a concentrated amount of anecdotal evidence that flying is worth fearing. Same thing with sharks. But I'm telling you, I would be that poor schmuck who survives a water landing as a result of lightning striking the plane, only to be devoured by sharks.