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AV8ORJWC
Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"
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 Posted: Mon Aug 28, 2006 5:55 am Post subject: AW: Access to tries for air |
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Almost every FBO uses dry nitrogen tanks - all turbine aircraft do. Compressed air contains moisture, ozone (extremely low) and oxygen which bring both corrosion of the rims and oxidized rubber to the table in the very long term. The only danger is over the life of the aircraft to the wheel halves and tire carcase. Pressure is no different so it is not self apparent to those who chose to take corners. Check with your local welding supply company on the long-term cost of a nitrogen tank. Air carriers have to discard perfectly good tires if they are accidently filled with air. Fire suppression upon a brake fire is the other reason for nitrogen filled tires. But then air carriers use phosphate ester (Skydrol) instead of H-5606 hydraulic fluid for additional protection.
John Cox - in Germany at the moment
Do not Archive
________________________________
Von: owner-rv10-list-server(at)matronics.com im Auftrag von Marcus Cooper
Gesendet: Mo 8/28/2006 6:13
An: rv10-list(at)matronics.com
Betreff: RE: Access to tries for air
I know the high pressure tires use nitrogen from an explosive resistance standpoint as well (If I remember right it was well over 300 psi in the Hornet when ready for carrier landings), but I have 2 questions for practicality for GA airplanes. What is the availability of nitrogen at the standard airport? Also, is there any danger in mixing Nitrogen and regular compressed air if you do need to top it off a little and there's no Nitrogen around?
Marcus
Do not archive
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Kellym
Joined: 10 Jan 2006
Posts: 1706
Location: Sun Lakes AZ
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| Posted: Mon Aug 28, 2006 11:36 am Post subject: AW: Access to tries for air |
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I can buy the argument of nitrogen for turbine aircraft because they
operate at much higher pressure and fly at altitudes where temps are
in the -20 to -60 range. However, your statement that airline tires
filled with air need to be thrown away defies logic. How do they keep
air away from the tires from the time they are made until they are
installed? How do they protect the tires being recapped? Why would it
make any difference if the tire misfilled was simply deflated,
dismounted, and any moisture wiped out? Is there some on line
reference to this policy?
The sum total mention of nitrogen in AC43-13-1B(chg 1) Chapter 9, page
9-11, consists of:
"NOTE: The use of nitrogen to inflate tires is recommended. Do not use
oxygen to inflate tires. Deflate tires prior to removing them from the air-
craft or when built-up tire assemblies are being shipped."
If there were hazards associated with air, you would think it would
get mentioned there. The reference to oxygen is obviously pure oxygen
which of course poses a fire hazard. Skydrol is much more fire
resistant than 5606, so don't see why that should be an issue. I can
see risks for tubeless tires, but GA planes all use tubes, so any
moisture isn't going to get to the inside of the wheel anyway. If you
have a brake fire severe enough to cause a leak or blowout in the
tire, the tire is likely to blow a hole and release all the pressure
very rapidly, and then what is in the tire makes little difference.
Quoting "John W. Cox" <johnwcox(at)pacificnw.com>:
| Quote: | Air carriers have to discard perfectly good tires if they are
accidently filled with air. Fire suppression upon a brake fire is
the other reason for nitrogen filled tires. But then air carriers
use phosphate ester (Skydrol) instead of H-5606 hydraulic fluid for
additional protection.
|
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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AV8ORJWC
Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"
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| Posted: Tue Aug 29, 2006 1:50 am Post subject: AW: Access to tries for air |
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Not going to explain the Air Carrier policy. When air is installed (by accident of course). Tire is required to be dismounted and returned for safety inspection. It is replaced with a correctly filled tire. The policy for nitrogen rather than compressed air should be clear. Many who chose to cut corners do so for economic reasons. Safety causes air carriers to throw copious amounts of money at known problems. Regulation causes unquestioned policy adherance. Choices due to ignorance which lead to higher insurance rates deserve a clarification.
The policy is so sound that turbo-prop and turbine GA use it as the model for safety and common sense. Seems executives who can afford those aircraft and the insurance required, see a value added in the use of nitrogen. As you go down the food chain the thrill of pursuit gets more fun.
My premise which was not to inflame, but was that those who are prudent, conservative or safety oriented might weigh the logic behind exclusive use of nitrogen rather than the poor man's alternative of moist air with oxidation of rubber and aluminum - the result. It is kind of like saving pennies and gambling that the issue will not arise with "my aircraft". Isn't Experimental a great way to encourage entrepreneurship and risk taking for the perception or thrill of the pursuit? Let the builder chose the path to be taken. Let's not make this a Primer/Alodine war for those who enjoy cutting the corners and making the choice. The response was for those who might not have understood oxidation effects on aluminum and rubber and asked as to the basis for the policy.
Kelly, may you fly boldly, long and safe. I just thought there was value in the points made. Sorry for the bandwidth.
John
Do not Archive - because most Experimental pilots make their own decisions and not because of a company, an industry or the government mandated safety concern.
________________________________
From: owner-rv10-list-server(at)matronics.com on behalf of Kelly McMullen
Sent: Mon 8/28/2006 12:36 PM
To: rv10-list(at)matronics.com
Subject: Re: AW: Access to tries for air
I can buy the argument of nitrogen for turbine aircraft because they
operate at much higher pressure and fly at altitudes where temps are
in the -20 to -60 range. However, your statement that airline tires
filled with air need to be thrown away defies logic. How do they keep
air away from the tires from the time they are made until they are
installed? How do they protect the tires being recapped? Why would it
make any difference if the tire misfilled was simply deflated,
dismounted, and any moisture wiped out? Is there some on line
reference to this policy?
The sum total mention of nitrogen in AC43-13-1B(chg 1) Chapter 9, page
9-11, consists of:
"NOTE: The use of nitrogen to inflate tires is recommended. Do not use
oxygen to inflate tires. Deflate tires prior to removing them from the air-
craft or when built-up tire assemblies are being shipped."
If there were hazards associated with air, you would think it would
get mentioned there. The reference to oxygen is obviously pure oxygen
which of course poses a fire hazard. Skydrol is much more fire
resistant than 5606, so don't see why that should be an issue. I can
see risks for tubeless tires, but GA planes all use tubes, so any
moisture isn't going to get to the inside of the wheel anyway. If you
have a brake fire severe enough to cause a leak or blowout in the
tire, the tire is likely to blow a hole and release all the pressure
very rapidly, and then what is in the tire makes little difference.
Quoting "John W. Cox" <johnwcox(at)pacificnw.com>:
| Quote: | Air carriers have to discard perfectly good tires if they are
accidently filled with air. Fire suppression upon a brake fire is
the other reason for nitrogen filled tires. But then air carriers
use phosphate ester (Skydrol) instead of H-5606 hydraulic fluid for
additional protection.
|
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http://www.matronics.com/Navigator?RV10-List |
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