Why A De Havilland Comet Was Repeatedly Submerged In Water

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The de Havilland DH.106 Comet was one of the most revolutionary planes in aviation history. It holds the title of being the first commercial jet airliner in the world. The aircraft’s first flight was in July 1949, and it was introduced in May 1952 with BOAC. However, following the type’s launch, it had some controversial moments in its early years. These incidents led to extensive research, which saw the Comet being submerged underwater.

De Havilland Comet
The de Havilland Comet 1, registration G-ALYP. Photo: Getty Images

Early warnings

The Smithsonian Magazine highlights that within the Comet’s first year of service, there was a lot of promise. It flew 104.6 million miles and carried 28,000 passengers along the way.

However, there were early signs of problems. On October 26th, 1952, a unit skidded off a runway in Rome following a broken landing gear. Then, the following year, there was a fatal accident when a Canadian Pacific Comet crashed on takeoff at Karachi, Pakistan. All 11 crew members and passengers died in the incident. The revisal of pilot instructions and a change in the wings’ leading edges addressed these problems.

Nonetheless, the Comet would still go through a series of dramatic events. In May of the same year, all 43 people died on a BOAC Comet performing Flight 783 when the aircraft broke up mid-air and crashed, following a sharp increase in wind speed near Kolkata.

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A detrimental year

1954 also kicked off to a bad start for the Comet. On January 10th, a de Havilland Comet performing BOAC Flight 781 had left Rome but exploded in the air before crashing into the sea near the Mediterranean island of Elba.

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Registration G-ALYP was the inaugural Yoke Peter, which was a name given to it due to the Royal Air Force phonetic alphabet system that was in use at the time corresponding to the last two letters of the jet’s registration number.

De Havilland Comet Fuselage Parts
The recovered pieces of the de Havilland Comet that crashed near Elba after leaving Rome. Photo: Getty Images

The tragic incident saw the fatalities of all 35 people on the plane and forced BOAC to instantly ground its Comets for inspection. The British Admiralty launched an operation to salvage the aircraft, which was sitting 500 feet below water. Nonetheless, within a month, the navy managed to bring the Comet’s tail, some of the fuselage, and other various parts back to land.

The pieces were then brought to the Royal Aircraft Establishment at Farnborough, United Kingdom, for inspection by a team of engineers and scientists.

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Following some tweaks, the planes returned to service a couple of months later in March. However, they were soon on the ground again after a month. This move followed an incident on April 8th, when a South African Airways Comet fell into the ocean while flying from Rome to Johannesburg. Sadly, all 14 passengers and seven crew members died. Subsequently, the Comet’s certificate of airworthiness was withdrawn

International concern

What followed was one of the most extensive aircraft accident investigations up until that point. Moreover, it was a difficult task due to the advent of modern technology being unavailable at the time.

These events had such an impact that even the Winston Churchill, the United Kingdom’s prime minister, intervened. He said that the price of finding a solution to the Comet mystery must be reckoned in neither money nor workforce. Ultimately, the credibility of British aircraft and the reliability of jet planes were at stake across the globe.

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Comet 1
The Royal Aircraft Establishment (RAE) at Farnborough, Hampshire, housed an entire Comet fuselage to examine the critical issues. Photo: Getty Images

Captain Ernest Rodley, who took part in the Comet inquiry, said that pressurization was the leading suspect of the issue on Flight 781.

The veteran pilot said the following, according to the Smithsonian Magazine.

“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.”

Rigorous testing

Therefore, to understand the impact of these cycles, a Comet fuselage was placed in a giant tank. Its interior was then sealed and filled with water.

Workers raised and lowered interior pressure at three-minute intervals. This process simulated cabin-pressure changes in a plane rising to 35,000 feet and then descending again. This constant testing accelerated the age of the Comet approximately 40 times faster than it would have during standard operations.

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Comet Interior
The view of the interior of the aircraft that underwent static pressure cycle tests. Photo: Getty Images

Following 1,800 cycles, the repeated pressurization forced the fuselage’s structure to burst. The failings were traced to a crack in the corner of a window above the plane where the radio aerials were placed. The splits continued for eight feet and passed directly through a window frame.

Additional analysis found that there was discoloration and crystallization. These factors are proof of metal fatigue. Ultimately, at high altitudes, after many pressurization cycles, the type’s fuselage could no longer contain high air pressure. So, the Comets would explode.

De Havilland Comet 1 Crack
A close look of the cabin window crack of the registration G-ALYP, following its recovery from the Mediterranean Sea. Photo: Getty Images

The damage is done

The BBC shares that improved construction techniques, the fitting of rounded windows, and other enhancements helped to ensure that later Comets were safe. Regardless, the Comet 1 would never carry another passenger again. Its successors, the Comet 2 and 3, would also see the same fate.

The likes of BOAC, Aerolíneas Argentinas, and East African Airways would operate the Comet 4. However, by this time, the type was overshadowed by the popularity of the Boeing 707. However, the Comet did continue to serve militaries for several decades.

Pan Am 707
Pan American introduced the Boeing 707 in 1958. Photo: Getty Images

Nonetheless, the de Havilland Comet was a pioneer when it came to commercial passenger jet aviation. It eventually addressed the failures that it encountered during its early days, but by then, it was too late.

What are your thoughts about the de Havilland Comet’s story? What do you make of the investigations following its accidents? Let us know what you think of the plane in the comment section.

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