Friday, April 27, 2018

Commentary: Metal fatigue in the sky; Movie, novel hit close to home

By Thomas V. DiBacco
Guest Columnist

Thomas V. DiBacco, a 1959 Rollins College graduate, is professor emeritus at American University.

The recent engine explosion on a Southwest Airlines 737 flight forced to make an emergency landing in Philadelphia was a terrible disaster, killing one passenger, and bringing the Federal Aviation Authority, responsible for airline safety, into the public forefront. To be sure, the nation has had a near-decade long commercial airline safety record, but the preliminary finding of the FAA was that metal fatigue on one of the engine's fan blades may well have been responsible, as it was for a 2016 Southwest flight with a similar explosion that, fortunately, landed without incident.

I've been interested in metal fatigue for years because my late and older brother, Arch, was a mathematician with a specialty in that area. At one time he worked for an aeronautical firm. As an historian and airline passenger, I've been interested in metal fatigue because, in the early days of commercial flying, it was a major cause of accidents and deaths. For example, from 1934 to 1981, a total of 306 aircraft accidents attributable to metal fatigue occurred, resulting in 1,803 deaths.

No movie brought the issue of aircraft metal fatigue into the fear factor of travelers more than “No Highway in the Sky” (1951), at a time when most Americans had not purchased their first ticket for a commercial flight. Featuring top-ranked actors and derived from a novel by Nevil Shute, who was in real life a pioneer aircraft designer, the movie was part fiction in that Shute, who worked for Britain's de Havilland Company, which produced the first commercial jet airplane, was ahead of his time, but a little imprecise of the crisis curve, that is, of the first instances of metal fatigue causing jets to crash.

Here's the eerie time sequence between fiction and real life: Shute wrote his novel in 1948; the de Havilland firm put in service the first jet, called the Comet, in April 1951. Shute's movie was released on Sept. 21, 1951. No problems were found with the Comet airplane until May 1953, when three fatal crashes occurred, two attributable to metal fatigue. In time, after putting the Comet out of service, the de Havilland Company found the problem, but the responsible area of the plane was different from Shute's novel.

Here's the movie plot and metal-fatigue difference. Actor James Stewart, an American mathematician, works for a British company that produces what is dubbed a Reindeer aircraft, which experiences a crash that Stewart is charged to investigate. A quirky scientist who has already spent years on the unraveling of metal fatigue, Stewart finds himself on a Reindeer jet that, he calculates onboard the flight, has exceeded the number of hours that, mathematically, would bring the jet down. He exhibits all sorts of fright on the plane, confiding to a once-famous actress (Marlene Dietrich) as well as a flight attendant (Glynis Johns), both eventually becoming sympathetic to his reasoning. Although he can't get the pilot to abort the flight and is surprised when the jet lands safely, he goes into the cockpit and retracts the landing gear, so that the aircraft is damaged and can't fly again.

Of course, this not only puts Stewart in hot water with his firm but the law and finds himself in court defending his sanity. There's much more to the story: Stewart is a widower with a young daughter living in a London apartment filled with junk and neglect (he hasn't even cashed seven monthly payroll checks). And there's a bit of a romance (as the Brits would say) between Stewart and Johns.

But here's the bottom line: when the jet that he damaged is repaired, on its way to taxing onto the field, its tail falls off, just as Stewart had calculated. His misstep was that he didn't take into account how temperature changes (flying in tropical regions, for instance) affected his calculations.

As for the real story of the Comet's metal fatigue, the problem was not its tail, but the square design of the passenger windows, leading to cracks along the four edges, causing the windows to blow and the cabin to decompress. The problem was solved by making the windows smoothly in an oval shape — a design, fortunately, still honored to this day.

But it took years before the Comet's issues were resolved, and it wasn't until October 1958 when transatlantic jet flights were introduced by a major American carrier, Pan American. By then, the small-sized Comet was on its way to the history books. I took my first flight on Pan Am from London to New York in September 1958 on what was still dubbed a prop-jet, taking 13 and a half hours. By then, the Israeli airline, El Al, offered jet service, cutting four hours off the journey. Recalling the 1951 movie, I opted for Pan Am.

Original article ➤

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