Our Experts on: Aircraft Tyres

February 20, 2008 at 4:00 am 2 comments

While we’re mainly focused on car and truck tyres on CarbonBlack, occasionally something comes along that piques our interest. In this case it was a question posted to our tyre expert David Matthews on aircraft tyres. Here’s David’s response:

The job that aircraft tyres have to do is very simple, but very specialised. They only have to track in a straight line, and operate within a narrow range of speeds. The epitome of this is, of course, a jet aircraft tyre. These have three layers of nylon built into the tread crown to hold the tread on at very high speeds (around 230 knots) – the nylon shrinks when hot, strengthening the hold.

The real issue is the amount of deflection they have to absorb on landing. Around 50% of the tyre section height (the distance between rim and ground) is lost on impact. The tyre flattens out, wears out after around 200-230 landings, (leaving furry bits of nylon protruding) and is retreaded, with the nylon replaced. While taxi-ing, the tyre deflection (percentage of section height lost) is around 30% on a jet, so some airports have limitations on plane weight when it has to taxi a long way in high temperatures.

The qualifying test for an aircraft tyre used to be (I have no recent knowledge, but it wouldn’t be any less today) that the tyre did 50 simulated landings without flaps at one hourly intervals – from memory around 180 knots. This is all done on a machine under controlled conditions.

The tyres operate at about 230 p.s.i on massively strong rims bolted together with massively strong bolts. This is possibly a bit removed from recreational aircraft tyres. What finally brings an aircraft tyre undone after six or seven retreads is fatigue in the lower sidewall, where the massively strong bead wire bundles (3 a side) are tapered into the flexible sidewall. So speed is not what it’s all about- reliability is. Comforting for recreational flyers!

Entry filed under: Our Experts, Safety, Tyre safety & maintenance, Tyre Technology. Tags: , , .

Michelin leads in online exposure from US study U.S. places import duties on Chinese Tyres

2 Comments Add your own

  • 1. David  |  October 20, 2010 at 11:14 am

    Goodyear USA is changing over to radial aircraft tyres as soon as possible, but it is a long process. However, the bulk of sizes for jet aircraft will be available during 2011. Radial tyres are lighter then bias ply,so save fuel, but as yet, do not take as many retreads, which adversely affects tyre costs . Had they been in use on the Concorde when the plane ran over a piece of metal on the runway at Paris, it is possible that the plane would have merely blown a tyre, not shredded it, which punctured the fuel tanks. Michelin later developed radials with 5 belts under the tread for Concorde, but too late, other factors intruded, and the plane is now a museum piece.

    Reply
    • 2. David  |  March 30, 2011 at 10:59 am

      Having just watched the A.B.C. doco on the Airbus 380 landing at Singapore with the blown engine, I remembered another qualifying test that aircraft tyres had to undergo to obtain certification. This was that at hourly intervals, the tyres were “landed’ ( on a machine) 50 times successively at speeds equivalent to the plane landing without flaps. So the least of the worries of the pilots was that the tyres would blow on touchdown, providing that they were all braked evenly. There was no doubt a risk that the 930 degree Celcius heat transmitted to the wheels from the brakes could have caused them to blow later, and some tyres appeared to have been changed before it was towed into the hangar. So the computer program that said they would have 100 metres of runway to spare, was correct!

      Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Trackback this post  |  Subscribe to the comments via RSS Feed



%d bloggers like this: