Tires: Where the Rubber Meets the Runway

Tires may be the Rodney Dangerfields of airplane components. They often don’t get the respect — or attention — they deserve for the outsize job they perform. After all, except for seaplanes operating on water, tires are literally where the rubber meets the tarmac of every flight.

Of course, there’s nothing glamorous or sexy about tires; but critical they are to every safe take off and landing on an airport runway. Improperly maintained tires can and have resulted in aircraft accidents. One accident I am familiar with that occurred before I was on the National Transportation Safety Board involved a DC-8 cargo airplane which blew three of its four tires on the left landing gear while landing at Boston’s Logan Airport. When we checked the pressure on the other tires, we found every one significantly underinflated. The fact that no fire resulted and that the aircraft was able to stay on the runway is more attributable to Logan’s 12,000-foot runway than the hazard that resulted from the blown tires. I have seen many fires that resulted from a pilot braking hard to stop on a short runway.

And a tire blowing apart can cause catastrophic damage to an aircraft. Many of you will remember the last flight of the Concorde in the summer of 2000. On take off from Charles DeGaulle Airport outside Paris, a tire blew after running over a piece of metal on the runway. Centrifugal force threw a piece of the tire into the underside of the wing, resulting in the rupturing of a fuel tank. Hot fuel on a hot brake caused a fire that consumed the aircraft, killing all 100 aboard and four on the ground. While tire maintenance was not a factor, this accident illustrates the danger to the aircraft from a blown tire.

NTSB records are replete with accidents and incidents caused or exacerbated by poorly maintained tires. (And NTSB records may not accurately reflect the number of tire incidents that occur since many are not reported if no aircraft damage or injuries occur.) Frequently, tire condition contributes to runway excursions, especially on slippery runways.

Too often I have found that mechanics skimp on their inspections of tires: a quick glance and a hand across the tire doesn’t count as a proper tire inspection. Far too often I have seen mechanics judge the condition of a tire by the tread alone. But tread wear is far from the sole determiner of a tire’s airworthiness. Just as critical are signs of cracking on the sidewalls caused by the stresses of landing — especially landing on underinflated tires.

Which brings me to the importance of proper tire pressure. There is no way to determine proper tire pressure without actual measurement — whether with a pressure gauge or, if you are lucky enough to be working on an aircraft with an electronic pressure monitor, an actual pressure reading. No matter how many decades you have looked at aircraft tires, there’s no substitute for actual measurement.

So next time you do an aircraft inspection, give those tires the respect safety demands.

 

John Goglia has 40+ years experience in the aviation industry. He was the first NTSB board member to hold an FAA aircraft mechanic’s certificate. He can be reached at gogliaj@yahoo.com.

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