If your tires have lost their slimy exponentially, and nylon cord [metal is Tire problems can be serious.
sidewall look, apply a protectant (such not used in the body of aircraft tires]
as Michelin’s Tire Care Spray). loses strength as it is heated. “At Mexicana 727 XA-MEM -- March 31, 1986
If you use inner tubes, use talcum some point, the tensile strength of the The PlaneCrashInfo site says, “While climbing
powder to let tire and tube move nylon is exceeded and the tire fails.” through 29,000 feet, an overheated tire exploded
relative each other. Tubes can be There are some weight advantages in the wheel well after takeoff and damaged the
re-used, but this is a recipe for to radial tire design, but they transfer hydraulic and electrical systems of the aircraft. The
pinching or folding the tube, since different kinds of stress to the wheels, plane lost control and crashed. The tire had been
a used (stretched-out) tube is so you cannot necessarily make up serviced with air rather than nitrogen.
considerably larger than a new one. the difference in overall weight of the “On takeoff,” I was told by a source familiar
When mounting a tire, never use wheel/tire system. Radials generally with the accident, “they had a dragging brake;
any type of petroleum product. A will offer more landings, because they the [wheel] plug didn’t come out. 167 people
dedicated mounting product (such can maintain a flatter tread pattern -- died. This accident led directly to the FAA’s
as Slyde, Murphy’s Black Lube, Tire- there is less built-in squirming; a radial nitrogen AD.“
Slick) is good; or a dilute soapy-water will usually run cooler, all things equal.
http://www.planecrashinfo.com/1986/1986-16.htm
solution may be all you need. Do not Bias-ply tires also tend to “grow”
use brake fluid, either conventional or more than radials at speed. (Some NationAir C-GMXQ – July 11, 1991
silicone-based. Though it generally will after takeoff checklists still include a An industry insider who didn’t want his name
not hurt rubber, it can cause slippage tap on the brakes, so the tire will stop in print told me, “There was a Canadian
between the tire and rim. spinning before it gets tucked away.) [chartered by Nigeria Airways as a pilgrimage
Most aircraft tires are still bias-plies. flight to Mecca] flight out of [Jeddah] Saudi
Just driving around is murder However, almost all new commercial Arabia – there was debate on what was going
on tires. and military tire applications will call on there; there were arguments as to the
Taxiing is unexpectedly hard on for radials, and some are even being extent of wear, and the inflation of the tires.
tires. Aircraft tires are designed for retrofitted. Mays, notes that, “Since A blowout was followed by a second blowout
intermittent use, so their temperature radials stress the wheel differently on takeoff; then there was a fire.” Things
buildup characteristics are totally from how a bias ply tire does, you deteriorated after that: “It [the fire] killed the
different from those of a road vehicle’s. can’t just mount radials without doing hydraulics. They crashed a mile or so short of
Run a car on the road long enough extensive analysis. Usually, wheels on the runway, as they tried to get back. There
(at a given ambient temperature, commercial and high-performance was a big hole in the fuselage; some bodies
speed, load, and pressure), and aircraft are already optimally- were pretty far from the actual crash site.
the tire temperatures will stabilize. designed, so you cannot simply switch 261 people were killed in that one. It wasn’t
Stan Mays, Manager of Military types. As new retrofits come on line, entirely bad tire maintenance, but that looked
Technical Programs with Michelin though, the military is insisting that like a contributor.”
says, “If you run an aircraft tire new wheels be radial-compatible. The Aviation Safety Network said, “Shortly
at rated load and rated pressure, The civilian world has a 14-item after take-off, at 2000-3000ft problems with
it will never reach an equilibrium checklist to allow a switch to radials; the cabin pressure were reported. These
temperature – temperature will keep the military does its own tests on its reports were quickly followed by a burst tire
rising until the tire fails.” Worse, as own aircraft, so they can switch where and loss of hydraulics. The aircraft lost control
distance increases, temperatures rise practical, more quickly. and crashed in flames while trying to return. It
appeared that two tires had failed during the
first 500ft of take-off and one had caught fire.”
http://aviation-safety.net/database/1991/910711-0.htm
Lear 35 N69PS -- July 13, 1994
This Lear 35 had a flat left outer tire, followed
soon by the other left and both right mains.
Other items complicated the scenario, but the
NTSB [US -- National Transportation Safety
Board] report said that, “company maintenance
personnel indicated the tires had been under-
inflated when they were built up and installed,
several days before the accident & that the
tires had not been checked or reinflated after
buildup. Goodyear reported the tires could
have been up to 50% under-inflated. An
exam of the tires disclosed evidence of under-
Does your preflight inspection include a sufficiently close look to catch FOD such as this?
inflation, & subsequent overheating.”
Aviation Maintenance |
avmain-mag.com | February/March 2010 19
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