Comet's Tale- page 2 | History | Smithsonian

Comet's Tale

A half century ago, the first jet airliner delighted passengers with swift, smooth flights until a fatal structural flaw doomed its glory

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Such high-flying planes, though, would need a pressurized cabin to allow passengers to breathe without oxygen masks. Pressurization would mean that as the airliner climbed to its cruising altitude nearly seven miles above the earth, the cabin would have to be pumped with air until its interior pressure exceeded the pressure outside the fuselage by about five pounds per square inch. As the plane descended to land, cabin pressure would have to be bled off again. Each cycle would put enormous stress on the plane’s structure; the tubular cabin would stretch slightly when pressurized, then contract as pressure was released.

Just three years after full-fledged design work commenced, De Havilland chief test pilot John Cunningham lifted the Comet off the ground for the first time and pronounced the plane “Very promising. Very quick.” Joining him as test pilots were Michael Majendie and Ernest Rodley, now 87, who became the world’s first certified commercial jet pilot. “I was able to get down to the Ministry of Aviation in London to get my license endorsed first,” says Rodley. “That’s the only reason I’ve achieved fame.” Of Majendie, an expert in flight planning, he says, “He was the brains, and I was the experience. Together we made quite a little team.”

The British Overseas Airways Corporation ordered eight of the airliners, and as word spread, other airlines came knocking on De Havilland’s door. Only one U.S. carrier, Pan Am, placed an order, for three larger, longer-range Comet 3s, which were still on the drawing board. For the most part, the American airline industry—then highly profitable with its existing propeller-driven fleets—had little interest in spending huge amounts of money for untried, fuel-guzzling jets.

In only its first year, the Comet flew 104.6 million miles, carrying 28,000 passengers. Then, on October 26, 1952, a Comet leaving Rome ran off the runway and skidded to a halt with a broken landing gear. The 35 passengers and eight crew members survived. Five months later, a Canadian Pacific Comet bound from London to Sydney crashed on takeoff at Karachi, Pakistan, and burned, killing all 11 passengers and the crew. An investigation revealed a flaw in wing configuration. Revised pilot instructions and a change in the wings’ leading edges solved the problem.

Then, two months later, a year to the day after the inaugural flight, a BOAC Comet with 43 passengers and crew disintegrated at 10,000 feet after leaving Calcutta in a heavy thunderstorm. Eight months after that, on January 10, 1954, something went terribly wrong at 26,000 feet on a BOAC flight a few minutes out of Rome. “I heard a roar, very high,” police quoted one eyewitness as telling them. “Then there was a series of blasts. The next thing I saw was a streak of smoke plunging perpendicularly into the sea.” The plane, the inaugural Yoke Peter, carried 29 passengers and a crew of six.

The next day, BOAC grounded all Comet flights. “Initially, we didn’t think it could be mechanical breakup,” says Captain Alabaster. “We had every confidence in the airplane.” Adds Ernest Rodley: “It was a perfect airplane as far as we were concerned. We were absolutely puzzled by the problems.” The Ministry of Civil Aviation launched the largest aircraft accident investigation ever undertaken at the time, and the British Admiralty started a salvage operation— no easy task, given that the plane had gone down in 500 feet of water.

Within a month, the navy had brought up a big section of Yoke Peter’s tail, along with skin from the fuselage and miscellaneous other parts. The wreckage was taken to the Royal Aircraft Establishment at Farnborough, England, for scrutiny by scientists and engineers. After investigators concluded that “there appeared to be no justification for placing special restrictions on the Comet aircraft,” the planes began flying again. Public confidence remained high; every seat on the first resumed flight was filled. But on April 8, even as Yoke Peter’s remains were still being assembled at Farnborough, a South African Airways Comet on a flight from Rome to Cairo lost radio contact at 35,500 feet and fell into the Mediterranean. Fourteen passengers and seven crew members were lost. Comets were immediately grounded for the second time in three months.

Prime Minister Winston Churchill now intervened. “The cost of solving the Comet mystery must be reckoned in neither money nor manpower,” he declared. At stake were no less than the credibility of the British aircraft industry and the viability of jet aircraft worldwide.

Yoke Peter’s reassembled pieces pointed to metal fatigue. But why? Pressurization was the leading suspect. Says Captain Rodley, who took part in the inquiry: “No one had taken into consideration the pressurizing cycles on the fuselage for a given time span, which were faster than the equivalent cycles in the slower, propeller-driven airplanes.” To gauge the effect of these cycles, an entire Comet fuselage was placed in a giant water tank, and its sealed interior filled with water. To simulate cabin-pressure changes in an aircraft climbing to 35,000 feet and then descending again, interior pressure was increased and decreased at three-minute intervals. Around-the-clock testing aged the Comet nearly 40 times faster than actual service.

In the meantime, autopsy reports from the Italian pathologist who examined the bodies of victims of one of the crashes indicated they had died “by violent movement and explosive decompression.” Evidence pointed to the catastrophic failure of the fuselage. The final clue, revealing the weakness in the Comet’s structure, turned up on June 24 in the tank at Farnborough, where the immersed test Comet had been subjected to the equivalent of 9,000 flying hours. Instruments showed a sudden drop in cabin pressure, indicating that something had happened in the tank.

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