All’s well that ends well, as was the case here, though it doesn’t make the story any less interesting/bizarre.
Last Thursday’s British Airways Airbus A380 flight from Hong Kong to London, BA32, faced a very strange situation. When the plane finished its climb out it received a tire pressure indication. The crew decided to continue the flight, but requested a tug in case they weren’t able to taxi themselves to the gate.
Since they were already enroute and the wheel was inside the belly of the plane, there’s not really a benefit to diverting. Even if there were an issue in London, at least they’d much more easily be able to fix the plane and accommodate passengers.
The aircraft landed safely on Heathrow’s runway 09L and taxied to the gate.
The aft right outboard body tyre caused a lot of head scratching trying to explain how the stunning square shape of the damaged tyre came together (editorial note: the original of the photo does not exhibit any indication of photoshopping).
Aft right outboard body tyre seen after arrival at the gate:
Yow! Does anyone with a better understanding of science than me want to take a crack at that one?
By the way, for anyone who doesn’t check The Aviation Herald frequently, I highly recommend it. It provides a summary of aviation incidents which occur on a daily basis, ranging from minor problems to crashes (with the latter being extremely rare, fortunately).
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The best explanation of this includes a comparison of what happens to your inner ear when flying;
During ascent the pressure within your ear (tyre) increases, forcing open the Eustachian tubes (small puncture) and venting the air molecules (any basic SCUBA diving webpage will give you the exact gas expansion calcs).
When you come to your descent, the air needs to find a way back into the ear (tyre), we can manually force this with...
The best explanation of this includes a comparison of what happens to your inner ear when flying;
During ascent the pressure within your ear (tyre) increases, forcing open the Eustachian tubes (small puncture) and venting the air molecules (any basic SCUBA diving webpage will give you the exact gas expansion calcs).
When you come to your descent, the air needs to find a way back into the ear (tyre), we can manually force this with our ears with techniques such as the Valsalva, opening up the Eustachian tubes to allow the air back in, without someone holding the small puncture in the tyre open the negative pressure created in the tyre will pull the hole closed at which point the negative pressure increases until you get to the ground.
The reason for the square shape is simple, the outer diameter of the wheel itself along with the profile (height) of the tyre only allows for a square shape when a negative pressure is held inside, for example there isn't enough material left (due to the profile of the tyre) to form a triangle shape but there is too much material for it to form a smaller circle.
The aircraft is probably equipped with radial constructed tires. In such tires, the reinforcements are layered at perpendicular angles to each other. Therefore as the tire deflated, the reinforcement layers retained their shape, which by the looks of it, were in a square pattern. The layers form the skeleton for the tires and provide the strength.
When I first started traveling for work my more experienced co worker insisted we take our rental car to an empty parking lot and "square the tires", literally just speeding up and hard breaking with various combinations of hand brake and mashing the pedals.
This though is the first time I've seen a square tire, and no, I don't do that to rentals myself, I was then as now too timid to have tried it.
If I were to take a guess, I'd presume it deflated slowly during flight from a relatively small leak and eventually equalized at the low pressure of the plane's cruising altitude, then when the plane descended to the higher-pressure sea level environment it crumpled due to pressure, just like a plastic water bottle or any other soft or semi-soft sealed container you might have with you. It just happened to crumple in something resembling a geometrically even shape.
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ChrisNew Member
July 12, 2016, 5:44 am
The best explanation of this includes a comparison of what happens to your inner ear when flying;
During ascent the pressure within your ear (tyre) increases, forcing open the Eustachian tubes (small puncture) and venting the air molecules (any basic SCUBA diving webpage will give you the exact gas expansion calcs).
When you come to your descent, the air needs to find a way back into the ear (tyre), we can manually force this with our ears with techniques such as the Valsalva, opening up the Eustachian tubes to allow the air back in, without someone holding the small puncture in the tyre open the negative pressure created in the tyre will pull the hole closed at which point the negative pressure increases until you get to the ground.
The reason for the square shape is simple, the outer diameter of the wheel itself along with the profile (height) of the tyre only allows for a square shape when a negative pressure is held inside, for example there isn't enough material left (due to the profile of the tyre) to form a triangle shape but there is too much material for it to form a smaller circle.
Hope this all helps.
CB
The best explanation of this includes a comparison of what happens to your inner ear when flying;
During ascent the pressure within your ear (tyre) increases, forcing open the Eustachian tubes (small puncture) and venting the air molecules (any basic SCUBA diving webpage will give you the exact gas expansion calcs).
When you come to your descent, the air needs to find a way back into the ear (tyre), we can manually force this with...
The best explanation of this includes a comparison of what happens to your inner ear when flying;
During ascent the pressure within your ear (tyre) increases, forcing open the Eustachian tubes (small puncture) and venting the air molecules (any basic SCUBA diving webpage will give you the exact gas expansion calcs).
When you come to your descent, the air needs to find a way back into the ear (tyre), we can manually force this with our ears with techniques such as the Valsalva, opening up the Eustachian tubes to allow the air back in, without someone holding the small puncture in the tyre open the negative pressure created in the tyre will pull the hole closed at which point the negative pressure increases until you get to the ground.
The reason for the square shape is simple, the outer diameter of the wheel itself along with the profile (height) of the tyre only allows for a square shape when a negative pressure is held inside, for example there isn't enough material left (due to the profile of the tyre) to form a triangle shape but there is too much material for it to form a smaller circle.
Hope this all helps.
CB
@Credit - I see what you did there , lol
Smart people on here.
The aircraft is probably equipped with radial constructed tires. In such tires, the reinforcements are layered at perpendicular angles to each other. Therefore as the tire deflated, the reinforcement layers retained their shape, which by the looks of it, were in a square pattern. The layers form the skeleton for the tires and provide the strength.
When I first started traveling for work my more experienced co worker insisted we take our rental car to an empty parking lot and "square the tires", literally just speeding up and hard breaking with various combinations of hand brake and mashing the pedals.
This though is the first time I've seen a square tire, and no, I don't do that to rentals myself, I was then as now too timid to have tried it.
If I were to take a guess, I'd presume it deflated slowly during flight from a relatively small leak and eventually equalized at the low pressure of the plane's cruising altitude, then when the plane descended to the higher-pressure sea level environment it crumpled due to pressure, just like a plastic water bottle or any other soft or semi-soft sealed container you might have with you. It just happened to crumple in something resembling a geometrically even shape.