When flying, deflate tires?

[ufkacbln]

i would be astonished if a single crash has been caused by inflating with air instead of nitrogen. Defective tyres I could believe - but the difference btween 78% nitrogen and 100% nitrogen - don't believe it

Google Mexicana Flight 940

One of the key findings as the cause was one of the wheels in the central undecarriage containing pressurised air as opposed to Nitrogen

If you still don't believe, take it up with the official investigators

 

[screenman]

Are the comparable in initial ticket price? I only ask as next year I intend to cycle a bit in other countries.

 

[Profpointy]

Google Mexicana Flight 940

One of the key findings as the cause was one of the wheels in the central undecarriage containing pressurised air as opposed to Nitrogen

If you still don't believe, take it up with the official investigators

I'm afraid I still don't believe. If they are really saying the margin os that tight that a little bit of oxygen os that disasterous they had already been sailing extremely close to the wind. Now if the nitrogen thing was one of a long list of failings along with not screwing the wings on properly or whatever, then fair enough

 

[Fab Foodie]

I packed my bike up for its first flight and deflated the tires almost completely. I've read people deflate complete to others who don't deflate at all. How about you?

Never do when I put the Brommie in the hold.

 

[ianrauk]

No point. Keep inflated. No one checks.

 

[Brandane]

Are the comparable in initial ticket price? I only ask as next year I intend to cycle a bit in other countries.

As always, it depends...... Obviously if I fly anywhere it's from Scotland which sometimes involves an extra flight to London/Amsterdam/Paris or wherever for a connection. That can severely bump up the price on the "budget" airlines. Strangely that isn't always the case on BA, in fact I posted about this at the time when I booked my flights to Orlando back in December. Flying Glasgow to London, then London to Orlando, the quoted cost was less than flying from London to Orlando! (I double checked it).
For European flights e.g. to Bordeaux 2 years ago - again by the time I had factored in the total cost of fare + luggage + whatever other extra charges various airlines throw in; I was cheaper flying with BA..

 

[classic33]

I'm afraid I still don't believe. If they are really saying the margin os that tight that a little bit of oxygen os that disasterous they had already been sailing extremely close to the wind. Now if the nitrogen thing was one of a long list of failings along with not screwing the wings on properly or whatever, then fair enough

http://aviation-safety.net/database/record.php?id=19860331-1&lang=en
Read the bottom of the page.
or
http://ecperez.blogspot.co.uk/2009/09/crash-of-mexicana-de-aviacion-flight.html

 

[ufkacbln]

I'm afraid I still don't believe. If they are really saying the margin os that tight that a little bit of oxygen os that disasterous they had already been sailing extremely close to the wind. Now if the nitrogen thing was one of a long list of failings along with not screwing the wings on properly or whatever, then fair enough

As I said, you can believe or not.... many sources reporting the official investigation of the crash

From the Aviation Safety Network,

Flight 940 took off from Mexico City (MEX) at 08:40 for a flight to Puerto Vallarta (PVR), Mazatlán (MZT) and Los Angeles (LAX). The left main gear brake was overheated during the takeoff run. When the aircraft had reached FL310 the heat caused a tyre on the left hand main gear to explode. Fuel and hydraulic lines were ruptured and electrical cables severed resulting in a cabin decompression. An emergency was declared, but spilt fuel ignited and caused a massive fire on board. Control was lost and the aircraft crashed into a mountain in the Sierra Madre, at an elevation of 9000 feet. It was found that the tire had been serviced with air rather than nitrogen. The air, under high temperature and pressure, resulted in a chemical reaction with the tire itself. This led to a chemical explosion of the tire.

Flight Safety Australia:

Nitrogen inflation serves a vital safety purpose in aircraft tyres, as demonstrated by the horrible fate of Mexicana Airlines flight 940. It was a Boeing 727 that crashed in 1986 after a dragging brake overheated a wheel on take-off, eventually causing an explosion and fire after the gear was retracted. All 167 on board died. The tyre had been filled with compressed air instead of non-flammable nitrogen. CASA airworthiness directive AD/WHE/4 mandates nitrogen inflation of tyres for aircraft with an MTOW of more than 5700kg, as well as for smaller aircraft if their tyres are speed-rated to more than 266km/h. The reason for using nitrogen is to eliminate the possibility of a chemical reaction between atmospheric oxygen and volatile isoprene gas (produced by severe heating of the tyre)causing an explosion.

The concensus is that the tyre was wrongly filled, caused an explosion which downed the aircraft


Please feel free to disbelieve, but if you wish to continue to challenge this, then you need to take it up with the investigators

 

[classic33]

Reading those, it was the brakes dragging that caused the overheating.
Causing the tyre to explode.
Fueling the fire, nitrogen wouldn't have fueled any fire.

 

[Ajax Bay]

Thanks to @Ffoeg :
"O2 does have a greater molecular weight (32) than N2 (28), but O2 is actually smaller in size. Thus, O2 fits through the relatively tight passage
ways between polymer chains in the rubber more easily than does N2. The difference is size between O2 and N2 is very [very, very] small, only about 0.3 times 10 to the -10th meters (0.00000000003 meters). O2 "permeates" approximately 3-4 times faster than does N2 through a typical rubber, as is used in tires, primarily
because O2 has a slightly smaller effective molecular size than does N2." (The O2 molecule is 'narrower' - see @Ffoeg 's link in post #27 for more, much more.)

 

[Brandane]

Reading those, it was the brakes dragging that caused the overheating.
Causing the tyre to explode.
Fueling the fire, nitrogen wouldn't have fueled any fire.

The exploding tyre also ruptured hydraulic lines and fuel lines, and severed electrical cables. The fuel ignited and from that point they were in trouble.

 

[classic33]

The exploding tyre also ruptured hydraulic lines and fuel lines, and severed electrical cables. The fuel ignited and from that point they were in trouble.

An exploding tyre filled with an inert gas wouldn't have fuelled the fire though.
Chances are it would explode, whatever you gas(es) you used. All other things being equal.

 

[Brandane]

An exploding tyre filled with an inert gas wouldn't have fuelled the fire though.
Chances are it would explode, whatever you gas(es) you used. All other things being equal.

Yebbut .... I don't think in this particular case the oxygen in the tyre would have contributed much to the fire. Leaking aviation fuel and severed electrical cables don't need much encouragement .

 

[Ajax Bay]

Chances are it would explode, whatever you gas(es) you used. All other things being equal.

The overheated tyre exploded BECAUSE O2 was present inside the tyre (ie 20% of the gas inside the tyre). If the gas inside the tyre had been N2 (100%) the explosive reaction would not have occurred. As @Cunobelin has quoted:
"The reason for using nitrogen is to eliminate the possibility of a chemical reaction between atmospheric oxygen and volatile isoprene gas (produced by severe heating of the tyre) causing an explosion."

 

[newfhouse]

Are the comparable in initial ticket price? I only ask as next year I intend to cycle a bit in other countries.

It cost me £28 on Easyjet CPH - LGW. I put the bike in a clear CTC bike bag, no damage. Good value, I thought.