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Some Questions About Tires?  
User currently offlineCobra27 From Slovenia, joined May 2001, 1016 posts, RR: 0
Posted (6 years 11 months 2 weeks 5 days 15 hours ago) and read 6510 times:

How much do they cost? The 747 Michelin tire I think is around 4500 $?
How many landings do they last an average? 150?
Do they blowout regulary? Are they changed frequently? How do they fill them with nitrogen

Tanks

51 replies: All unread, showing first 25:
 
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5470 posts, RR: 14
Reply 1, posted (6 years 11 months 2 weeks 5 days 14 hours ago) and read 6502 times:

Quoting Cobra27 (Thread starter):
Do they blowout regulary?

No.

Quoting Cobra27 (Thread starter):
Are they changed frequently?

No. They are changed on condition.

Quoting Cobra27 (Thread starter):
How do they fill them with nitrogen

Much like your car or bike tire; through a fill valve in the wheel.



When seconds count...the police are minutes away.
User currently offlineB78710 From United Kingdom, joined Mar 2006, 343 posts, RR: 0
Reply 2, posted (6 years 11 months 2 weeks 5 days 13 hours ago) and read 6495 times:

Quoting Cobra27 (Thread starter):

they get changed when they get worn down to the core braid basically!

unless you find any individual deep cuts in the tyre that expose the braid, that will also warrant a wheel change!


User currently offlineTristarSteve From Sweden, joined Nov 2005, 4015 posts, RR: 34
Reply 3, posted (6 years 11 months 2 weeks 5 days 13 hours ago) and read 6486 times:

Quoting Cobra27 (Thread starter):
How many landings do they last an average? 150?

I would say around 500 landings, about every 4 months for a short haul aircraft.
With modern radial ply tyres, about 99pc are changed because they are worn out, They are extremly resistant to cuts and other damage.
Older cross ply tyres are more susceptible to punctures but only a little, maybe 97pc are changed due worn out.

I have worked on the line on A320 since 1988, and have NEVER changed a tyre for damage.

When I worked on B737-400 with cross plies, I changed about one a year for a puncture (4 flights a day).


User currently offlineKELPkid From United States of America, joined Nov 2005, 6398 posts, RR: 3
Reply 4, posted (6 years 11 months 2 weeks 5 days 8 hours ago) and read 6429 times:

Quoting B78710 (Reply 2):
they get changed when they get worn down to the core braid basically!

unless you find any individual deep cuts in the tyre that expose the braid, that will also warrant a wheel change!

Flat spots (in GA aircraft, at least  Wink ) can be caused by an over anxious pilot on the brakes, or even landing with the brakes engaged, and lead to premature tire replacement.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 5, posted (6 years 11 months 2 weeks 5 days 8 hours ago) and read 6420 times:

ERJ-145 we had to change them when there was less the 2/32 in of tread left or due to tire damage. Normally I think they last about 45 days for a main tire.

User currently offlineScooter01 From Norway, joined Nov 2006, 1204 posts, RR: 8
Reply 6, posted (6 years 11 months 2 weeks 5 days 4 hours ago) and read 6379 times:
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Sometimes I guess they just park them instead of changing the tires  duck 

Big version: Width: 1024 Height: 1536 File size: 1106kb

MiG-25 in Riga


Scooter01



"We all have a girl and her name is nostalgia" - Hemingway
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 7, posted (6 years 11 months 2 weeks 5 days 4 hours ago) and read 6369 times:

Most tires are not actually new on an airplane unlike cars. Tires can be retreaded many times. You get new tires out of the factory, but after that unless there is a problem with the tire, it will be reused.

Quoting TristarSteve (Reply 3):
When I worked on B737-400 with cross plies, I changed about one a year for a puncture (4 flights a day).

Finally the 737 will be moving to radial tires within the next year or so. It's been a long time in development to switch them, but hopefully it will help.



If you have never designed an airplane part before, let the real designers do the work!
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 8, posted (6 years 11 months 2 weeks 5 days 3 hours ago) and read 6353 times:

Quoting Fr8Mech (Reply 1):
Much like your car or bike tire; through a fill valve in the wheel.

Its called a Schader Valve. The are also used on the landing gear for air charges.


User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 9, posted (6 years 11 months 2 weeks 5 days 2 hours ago) and read 6344 times:

Quoting 474218 (Reply 8):
Its called a Schader Valve. The are also used on the landing gear for air charges.

I have only see schader valves on struts and hyd. accumulators. All the valve stems on the tires I have serviced from a ERJ-145 to a 747 are just like a valve stem on a car or truck tire.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6398 posts, RR: 3
Reply 10, posted (6 years 11 months 2 weeks 5 days 2 hours ago) and read 6341 times:

Quoting 474218 (Reply 8):
Its called a Schader Valve. The are also used on the landing gear for air charges.

I remember one time, when stranded at a remote airfield (due to a nose strut that had deflated on the ramp overnight) in New Mexico, trying to inflate the nose strut in a Cessna 172 with a nitrogen bottle (note: I'm not a mechanic  Wink ). Well, I ended up getting sprayed with pink, oily-smelling goo  Sad So I ran into town from the airport, and got ahold of the plane's mechanic (via payphone) back at the home base who told me "Have someone hold the tail down next time, you idiot!"  Embarrassment BTW, it's just a standard Schrader valve on top of the nose strut...



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 11, posted (6 years 11 months 2 weeks 5 days 1 hour ago) and read 6326 times:

Quoting A10WARTHOG (Reply 9):
All the valve stems on the tires I have serviced from a ERJ-145 to a 747 are just like a valve stem on a car or truck tire.

The valve stem used on car and truck wheels is a Schrader Valve, just like the one used on aircraft tries and landing gear struts. While the aircraft my hold a little more pressure than the ones on your car, they share the same basic design. I use aircraft Schrader Valve caps (the yellow ones) on my car.


User currently offlineB78710 From United Kingdom, joined Mar 2006, 343 posts, RR: 0
Reply 12, posted (6 years 11 months 2 weeks 5 days 1 hour ago) and read 6321 times:

Quoting 474218 (Reply 11):

i've always known a scraeder valve to be the type used to charge accumulators!

wind on the fitting and air line, open the valve, charge to required pressure, close the valve and remove the adaptor and hose!

always release the pressure before removing the hose though  Wink i know someone who learnt that the hard way


User currently offlineScooter01 From Norway, joined Nov 2006, 1204 posts, RR: 8
Reply 13, posted (6 years 11 months 2 weeks 5 days ago) and read 6309 times:
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Quoting 474218 (Reply 8):
Its called a Schrader Valve. The are also used on the landing gear for air charges.

You can also see them integrated in the Boston-valve for inflated water-sport articles, like a Le Tube for instance, for easier filling at a gas-station.....

Scooter01



"We all have a girl and her name is nostalgia" - Hemingway
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5470 posts, RR: 14
Reply 14, posted (6 years 11 months 2 weeks 4 days 19 hours ago) and read 6259 times:

The tire servicing valve is not a Schraeder valve, it is a valve with a removable core. In order to service the tire, you just apply the service chuck with enough pressure to unseat the core.

A Schraeder valve has a 3/4" jam nut on it which allows the user to open or close the valve as required to service.

The inflation valve may be based on a design by Schraeder, but is not what is commonly called a Schraeder valve, at least not in my 20 years in maintenance.

Some B747 aircraft I've been exposed to had larger diameter valve stems, but functioned the same.

But the caps are interchangeable.

I know, anal, but this industry is getting tough enough without us losing our language and terminology.



When seconds count...the police are minutes away.
User currently offlineBok269 From United States of America, joined May 2007, 2104 posts, RR: 0
Reply 15, posted (6 years 11 months 2 weeks 4 days 19 hours ago) and read 6253 times:

QUick question: what is the typical PSI of an aircraft tire?


"Reality is wrong, dreams are for real." -Tupac
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 16, posted (6 years 11 months 2 weeks 4 days 17 hours ago) and read 6241 times:

Quoting Cobra27 (Thread starter):
How much do they cost? The 747 Michelin tire I think is around 4500 $?

When the did the 777 RTO test they ruined all 12 tires and I think they said it cost about $250000...that works out to about $20000/tire.

Quoting Bok269 (Reply 15):
QUick question: what is the typical PSI of an aircraft tire?

A 737 is anywhere from 120 to 205 psi (cold), depending on conditions.

Tom.


User currently offlineB78710 From United Kingdom, joined Mar 2006, 343 posts, RR: 0
Reply 17, posted (6 years 11 months 2 weeks 4 days 12 hours ago) and read 6207 times:

Quoting Bok269 (Reply 15):
QUick question: what is the typical PSI of an aircraft tire?

744 main gear 200-205 psi nose wheels 175-180 IIRC


User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 18, posted (6 years 11 months 2 weeks 4 days 10 hours ago) and read 6191 times:

Quoting Tdscanuck (Reply 16):
When the did the 777 RTO test they ruined all 12 tires and I think they said it cost about $250000...that works out to about $20000/tire.

Did that cost include new wheels and brakes? Everything caught fire in the test.

Interesting fact:
On all Boeing planes like the 737 and 777, the landing gear is the second most expensive part on the airplane that comes from a supplier.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 19, posted (6 years 11 months 2 weeks 4 days 10 hours ago) and read 6187 times:

Quoting RoseFlyer (Reply 7):
Tires can be retreaded many times.

Ah ah! Hold on sec on that....thats not necessarly true. Certain aircraft tires can only be retreaded a certain amount of times. It all depends on the tire manufacturer and the aircraft type.



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4015 posts, RR: 34
Reply 20, posted (6 years 11 months 2 weeks 4 days 9 hours ago) and read 6183 times:

Quoting AirframeAS (Reply 19):
Ah ah! Hold on sec on that....thats not necessarly true. Certain aircraft tires can only be retreaded a certain amount of times. It all depends on the tire manufacturer and the aircraft type.

Yes allowable retreads on airline tyres are from 0 to about 10 times before the tyre is scrapped.


User currently offlineB78710 From United Kingdom, joined Mar 2006, 343 posts, RR: 0
Reply 21, posted (6 years 11 months 2 weeks 4 days 9 hours ago) and read 6175 times:

Quoting TristarSteve (Reply 20):

does the tread depth change each time? or will the tenth tread be as deep as the first?

not been in the game long, but all the wheels ive changed, i think the new ones have always been brand new, certainly had that "new" look to them anyway, you know you get those little strands of rubberon the surface?


User currently offlineTristarSteve From Sweden, joined Nov 2005, 4015 posts, RR: 34
Reply 22, posted (6 years 11 months 2 weeks 4 days ago) and read 6110 times:

Quoting B78710 (Reply 21):
does the tread depth change each time? or will the tenth tread be as deep as the first?

No it is the same.

Quoting B78710 (Reply 21):
i think the new ones have always been brand new, certainly had that "new" look to them anyway, you know you get those little strands of rubberon the surface?

Retreaded tyres look brand new. We are not talking about regrooved tyres here. The whole cap is new. The only way to tell if a tyre is retreaded is to look at the sidewall. You can see the original tyre, and the retread, and the join. Sometimes the retread is a different manufacturer from the original.
By the way the shelf life of a retreaded tyre is 10 years from date of original tyre manufacture. Might not seem significant but on a line station we sometimes send tyres back because they are time expired!!


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 23, posted (6 years 11 months 2 weeks 3 days 23 hours ago) and read 6093 times:

Quoting RoseFlyer (Reply 18):
Quoting Tdscanuck (Reply 16):
When the did the 777 RTO test they ruined all 12 tires and I think they said it cost about $250000...that works out to about $20000/tire.

Did that cost include new wheels and brakes? Everything caught fire in the test.

That's a darn good question and I don't know the answer. They certainly would have had to replace the brakes and at least overhaul the wheels (plus, obviously, new tires).

Tom.


User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 24, posted (6 years 11 months 2 weeks 3 days 22 hours ago) and read 6079 times:

Quoting TristarSteve (Reply 22):
The only way to tell if a tyre is retreaded is to look at the sidewall. You can see the original tyre, and the retread, and the join.

It also indicates, for example, the tire has been retread 5 times after the manufacturer retreaded it.



A Safe Flight Begins With Quality Maintenance On The Ground.
25 Jetstar : On the Lockheed JetStar, tire pressures were 205 psi, cold, mains and nose and dry nitrogen was used to inflate the tires. This pressure was to high t
26 474218 : The number of times the tire will be stamped on the side with the Letter R and a number, such as R12.
27 AirframeAS : Yeah, thats what I said....
28 Lrdc9 : Why do they use nitrogen for a/c tires?
29 Post contains links 2H4 : The nose tire on an F-16 takes 300psi. Here you go 2H4
30 Tdscanuck : It helps prevent oxidation on the inside of the tire, but the biggest reason is flammability. A tire can get very hot while taxiing, so hot that the
31 Cobra27 : Some where on the web is the PDF from Michelin with some ingo about their aviation tires
32 HAWK21M : B752 150psi Nose Wheel & 180-186psi Mainwheel approx depending on Wheel Temperature. regds MEL
33 Ha763 : I just had to clear a 747 tire assembly through Customs today. The invoice value was over $15,000. A little over $1400 for the tire (foreign made) an
34 B78710 : ahhh ok, i assumed it was just the actual tread was recut will have to look out for that! thanks!
35 NEMA : Ive always wondered this, it has been a thought over time that ive had especially where there are only two tyres per strut like on the 737 or A319 as
36 Jetstar : For certification purposes, any airplane that has a 2 wheel main landing gear, each tire must be able to support the aircraft at the maximum weight i
37 MD11Engineer : On recapping the tire will be ground down on a kind of lathe to just below the thread reenfocement fabric layers. Then a new cap with grooves will be
38 VAAengineer : VS 747 wheel is 15000USD VS A346 wheel is 30000USD
39 2H4 : Do any technical factors account for the large price difference, or is it simply a matter of Airbus charging more for essentially the same thing? 2H4
40 Tdscanuck : I would guess that economies of scale enter in there...there are a whole lot more 747 tires in the world than A346 tires. Tom.
41 2H4 : If that's the case, I wonder why Airbus was unable to utilize a more standardized wheel...I wonder what might be specialized and/or unique about the
42 JetMech : It may also be the fact that an A330 / A340 main wheel assembly is physically much larger that a 747 wheel assembly. Regards, JetMech
43 WingedMigrator : And every time a 747 is scrapped, another 16 wheel rims arrive on the market? Even $15K sounds like more than the scrap value of the aluminum. Anothe
44 Lemurs : I was thinking the same thing...the engineering and tolerances on the A346 wheels are probably tighter than the 747 due to their different operationa
45 B78710 : alos quite a bit bigger!
46 Readytotaxi : Gosh, does a modern aircraft allow you to land with the parking brake on ???
47 TristarSteve : The worst tyre failure I have experienced was on a GF L1011 taking off from BAH for LHR about 1980. It was about 0100 and one of the fwd main wheels
48 HAWK21M : No.Locked wheel protection prevents it. I found Aquaplaning to cause a lot of damage to Tires especially in the rainy season out here, regds MEL
49 Post contains images KELPkid : I hear some Embraer pilots have managed to do just this...
50 2H4 : It's almost humorous, isn't it? In today's day and age, our newest, most technologically advanced aircraft can identify the flight path, examine the
51 HAWK21M : Yeah that was real bad.I remember those pics. regds MEL
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