At Paine Field, they’re restoring seminal jetliner, the Comet

EVERETT — The old jetliner’s interior hardly resembles what it looked like 20 years ago.

Slime and mold covered nearly every surface of the de Havilland Comet 4C when the Museum of Flight got it in 1995. It had already spent more than a decade parked outside at Paine Field. The historic airplane’s aluminum body was riddled with holes from corrosion.

The Comet is a classic it launched the jet age in 1952, and many thought Britain might dominate the jetliner market. But just as the airplane introduced many innovations, it taught painful lessons about the pressures and stresses put on passenger jet airplanes.

For the past two decades, hundreds of volunteers have put in more than 200,000 hours restoring the historical jetliner at the museum’s Restoration Center at Paine Field, said Tom Cathcart, the museum’s director of aircraft restoration.

“Just about everything in here has been removed and reinstalled,” he said.

The volunteers have cleaned, repaired or replaced everything from the gauges and rows of toggles in the cockpit to the shining stainless steel fore galley and the light-beige seat upholstery on the 81 seats.

The jet is a time machine, said Bob Hood, the volunteer who ran the project until stepping down earlier this year, “When people step into it, it will look almost exactly how it did” when it was built in 1959.

Cathcart figures the Comet restoration project is about 70 percent finished.

Its flying days are over, though. When it moves to Seattle to go on permanent display in the next few years, it will get there by barge or by truck, he said.

Its place in the museum’s collection was never in doubt.

A de Havilland Comet 1 operated by the British Overseas Airways Corporation changed the world on May 2, 1952, when it left London bound for Johannesburg on the first commercial jet flight. A one-way return ticket in today’s dollars cost about $8,000.

The British-built airplane offered flyers a smoother, faster and quieter ride relative to the prop planes that dominated the skies, such as the Lockheed Constellation and Douglas DC-7. It cut hours, even days off travel times.

The sleek jetliner incorporated several technological advances, including hydraulic-power flight controls and landing gear assemblies with multiple wheels — called bogie landing gear.

Its four engines were buried in the wings rather than hung below, giving it clean, aerodynamic lines.

“It was a beautiful piece of aluminum sculpture,” Hood said.

The creation of the jetliner was in itself remarkable. The idea for the airplane came in the depths of World War II. While most of the country was focused on defeating the Axis powers, a UK government committee led by British aviation pioneer Lord Brabazon tried to anticipate the types of passenger airplanes the country and its far-flung empire would need after the war.

De Havilland committed to building a jetliner in 1943, though intensive design did not start until 1946. In only took three years to go from the drawing board to the prototype Comet 1’s first flight. It was a genuine conceptual breakthrough, said Keith Hayward, a Royal Aeronautical Society fellow who has written extensively about the post-war and current aerospace industry in the UK.

The Comet 1 only had room for 44 passengers in a typical layout and a range of about 1,500 miles. While it was too small and its range was too short for it to be anything more than a technology demonstrator, “it still caught a wave of orders and helped to push Americans into their jet designs,” he said.

The follow-on version, the Comet 3, “was the real deal,” he said. It could hold enough passengers — 58 to 76 — for airlines to make money flying it. A one-way ticket from London to New York on a BOAC flight in 1958 cost the equivalent of $3,561 today.

Many in the UK thought that the Comet and the country’s aerospace industry were poised to dominate the jetliner market for years to come.

But the industry was still learning about jet travel.

For its jet engines to work efficiently, the Comet had to fly at about 40,000 feet, far above where propeller planes operated. Like current jetliners, the Comet’s cabin was pressurized to about 8,000 feet in flight. That difference in pressures put stress on the airplane’s body.

After wowing the world in 1952, three Comets crashed in high-profile accidents during the next two years. Everyone on the three airplanes, 99 people in all, died.

After the last crash in 1954, the Comet fleet was grounded. Aviation authorities in the UK launched an extensive investigation to figure out why Comets were coming out of the sky.

The committee’s work changed accident investigation practices around the world.

Using the latest available scientific technologies and forensic methods, investigators located and salvaged one of the aircraft’s remains from the Mediterranean Sea. Then they reconstructed the airplane to determine possible causes. They tested their lead theory — structural failure and explosive cabin depressurization — by putting a Comet in a giant water tank and changing the water pressure inside the cabin to simulate repeated flights.

After thousands of simulated flights, the Comet’s body tore apart, confirming the airplane’s design flaws.

The Comet’s designers had not understood just how much wear and tear repeated pressurization and depressurization put on the airframe, or that the new method of punching out rivet holes produced microscopic stress fractures in the metal skin. They also didn’t understand that the mostly square shape of the airplane’s windows concentrated stress around the corners, rather than distributing the stress, as with oval-shaped windows.

As a result, cracks formed and spread in the skin of three Comets, causing the fuselages to tear apart in flight.

At the time, Lord Brabazon said, “In every step and progress, we’ve had to pay for it in blood and in treasure. And, God knows that in this case we have paid in full.”

The de Havilland company redesigned the airplane, producing the Comet 4, the variant owned by the Museum of Flight.

The Comet 4 entered service in 1958, but it was followed a few weeks later by the Boeing 707. The Douglas DC-8 came along in 1959.

Airlines could make more money off of the two larger, more fuel-efficient American airplanes, which quickly dominated the early jetliner market. Airlines eventually ordered 1,010 707s and 556 DC-8s. Only 114 Comets were ever delivered.

De Havilland never recovered.

“The Comet failure was a blow to morale” in the UK aerospace industry, Hayward said. But its subsequent failure had more to do with a lack of industrial capacity and capital, and designs driven by state-owned airlines, which “fatally injured wider sales prospects.”

It was “all a bit of a mess and hubris,” he said.

A modified Comet called the Nimrod was used by the Royal Air Forces until 2011. The UK Ministry of Defence provided several spare Nimrod parts to the restoration project.

The museum’s Comet 4 was delivered to Mexicana Airlines in 1960, the first of three Comets flown by the airline. It was used in the airline’s “Golden Aztec” jet service. A massive, hand-painted Aztec calendar adorned the airplane’s vertical fin.

The fin is currently disassembled, leaning against a wall in one of the Restoration Center’s hangars.

Mexicana parked its Comets in 1970, and later sold two to an airplane broker in Arizona. One of those was then sold to a subscription airline based in Redmond. While flying to Olympia in 1979, an engine warning light came on, and the airplane diverted to Paine Field. Federal aviation authorities grounded the airplane due to its questionable maintenance history.

“It came here and it never left,” Cathcart said.

For several years, the Everett Community College used it for its aircraft and powerplant mechanic training program. The college donated it to the museum in 1995.

The Comet is parked, part inside the hangar, part outside. It’s wings are too wide to fit inside the building, so they are covered with a giant, improvised tent made of white plastic sheets supported by two-by-fours.

A balcony ringing the hangar inside is packed with spare parts, everything from a radio direction finder for navigation to the skins covering the engine exhausts.

If volunteers can’t find a spare, they have to make it, a process that requires a lot of research and some guesswork. Often the machining is done by 100-year-old volunteer Jim Jackson.

De Havilland merged in the 1960s and again in the 1970s. At some point, the original design specifications for the Comet were thrown out. So, all the restoration volunteers have to go by are two shelves of blue binders of maintenance manuals, overhaul manuals and parts catalogs that came from Mexicana. The well-worn books have detailed drawings showing how and where everything on the airplane belongs from the smallest screw to the massive jet engines.

But there are no dimensions for the parts, no specifications for how they are made, said Paul Lehtinen, who’s volunteered on the project for nearly five years.

On Wednesday, he was attaching pressed metal trim to an access panel cover for one of the rear bathrooms. The trim had to be machined in a tool shop in the hangar.

Designing, producing and attaching the quarter-inch wide trim took weeks, he said.

Much of the rear bathrooms and galley is still torn up. Tools and spare materials are scattered about.

“I see a lifetime of work here,” he said. “It keeps me thinking ‘cause I’m constantly trying to solve problems.”

Like many of the project’s volunteers, the 71-year-old is retired, a former welder and equipment installer. That experience serves him well on the Comet, where he spends about 20 hours a week.

“Nuts and bolts are still nuts and bolts whether on an airplane or a tractor,” the Everett resident said.

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com;Twitter: @dcatchpole.

De Havilland Comet

Location: Museum of Flight Restoration Center

Manufacturer: De Havilland Aircraft Company Ltd.

Model: D.H. 106 Comet Mk. 4C

Year: 1959

Serial Number: 6424

Registration: N888WA

Capacity: 71 passengers (22 first class)

Wingspan: 114.83 ft

Length: 118 ft