The Dreamliner is a magnificent fuel-efficient flying machine. I’m going with the teething-problem theory regarding the FAA grounding. But if you’re jettisoning Boeing stock, you might want to consider Bridgestone or Goodyear. Blown tires are in the news.
On Monday, a Southwest flight aborted a DEN takeoff because of a cockpit warning light. Abrupt braking caused three tires to blow.
On Sunday night at EWR, a United Express flight blew four tires and veered off the runway while landing.
Also on Sunday, at Toronto’s YYC, a wheel fell off an Air Canada Jazz Bombardier Q400 while taxiing to the gate after landing.
Some of these arrhythmia producers were witnessed by FT members.
You could argue that aircraft like the Dreamliner are about as complex as technology can get in 2013. What other machine can take itself to Fiji while heating up dinner for a few hundred folks? But in the end, hopefully, it all comes down to that x-y-vector moment when rubber hits the tarmac.
Maybe tires are both the bedrock and quicksand of aviation. Everything is riding on plain old plane tires. Everything on landing tethered to five-eighths of an inch or less of tread. (I’m told stock tires on a new Dreamliner and Airbus 320 are Bridgestone radials – 5/8 inch tread.)
So what’s the story with aircraft tires? They trick the aircraft into thinking they’re part of her and then leave her behind. Following is a bit of research, but I’m hoping for some comments from better minds than mine. My stuff might be all hooey.
My neighbor is a Delta pilot and I got most of this from him. In the telling he painted a pretty full canvas with no evident motive other than kindness.
Aviation is a banzai assignment for rubber. When planes land there’s no spin on the tires. They screech along the runway until they come up to speed. Maintenance folks call it “spin-up time.” We see it as little white puffs of smoke and the process can leave a tire looking like an overripe peach.
Airlines yank the tires when they approach their wear limits so the cores can be recapped, my pilot neighbor says. Yep, most times we’re flying on retreads. Operating cost per landing is how the bean counters rate tires.
As a general rule, a tire is good for 100 to 150 landings, which seems surprisingly few but is influenced by many variables. Hard landings scrub bare spots into the tire. Landing on debris can cut a tire. Lousy runway construction and poor maintenance rips at tires. And when that Dreamliner finds its way to Fiji, crushed seashells added to the tarmac take piranha-sized bites out of tires.
A mechanic can change an aircraft tire in 15 minutes while passengers remain onboard. They fill them with nitrogen. (The tires, not the people.) Two out of three replacements are nose tires.
“I’ll bet you a bail of hay I know what caused some of those tire incidents this week,” said my neighbor. “Those tires had fuse plugs. If you’re hard on the brakes, like during an aborted takeoff, the heat from the brakes cause the fuse plugs to melt so the tire can deflate rather than explode, preventing potential damage to the airframe and maybe safety for responding fire crews.”
Are you telling me those were flat tires and not blown tires? “Probably,” he said.
“The Southwest pilot did everything right if that warning light came on. The United Express guy is maybe heavy on the brakes coming into Newark through a small window. Maybe he was a hero. You don’t whistle your own tune up there. But I’m just a pilot, not a rocket scientist. We’re paid to bring you home and he did that.”
I asked my neighbor if he ever thinks about tires on final approach. “No more than when I’m driving my pickup,” he said. “But I always kick the tires on the equipment before takeoff.”
That’s about as many miles as I can get out of aircraft tires. I think most of the miles are true. The topic is all yours. Please set me straight in your comments. The job of a writer is to remind the reader how smart they are. It’s been a cold January on the ranch and I can take the heat. A barn loses its character and just goes to dust if no animals bray into the night.
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