In an industry renowned for high performance and complexity, the Lockheed Martin Corp. supersonic F-35 Lightning II stands out as being in a league of its own. This is true both in terms of the airplane’s inherent capabilities and the assembly challenge it poses.

In an industry renowned for high performance and complexity, the Lockheed Martin Corp. (Bethesda, MD) supersonic F-35 Lightning II stands out as being in a league of its own. This is true both in terms of the airplane’s inherent capabilities and the assembly challenge it poses.

Intended to replace a wide range of aging fighter jets-including the Harrier jump jet, the A-10 “Warthog,” the F-16 Fighting Falcon and the F/A-18 Hornet-the F-35 features stealth technology and powerful sensors. It will be available in both conventional and vertical-takeoff variations to meet the different needs of the U.S. Air Force, Navy and Marine Corps.

Although Lockheed Martin is serving as the prime contractor for the $200 billion project-having prevailed in a protracted design competition with the Boeing Co. (Chicago) in 2001-it is working with dozens of partners and suppliers in eight other countries, including the United Kingdom, Italy, the Netherlands, Turkey, Canada, Australia, Denmark and Norway.

Lockheed Martin will perform final assembly of each F-35 at its cavernous, mile-long plant in Fort Worth, TX. But, Northrop Grumman Corp. (Los Angeles), one of two principal industrial partners, will build each airplane’s center fuselage, while BAE Systems plc (London) will manufacture each airplane’s aft fuselage and tail at a plant in Samlesbury, England.

Further complicating things, is the fact that the F-35 will be manufactured in unprecedented numbers. As of this summer, there were 14 Lightning II preproduction test aircraft in various stages of assembly and one in flight test. However, production numbers will mushroom in the coming months. The United States plans to purchase more than 2,400 aircraft, the United Kingdom plans to buy 138 airplanes, and the seven other participating nations intend to acquire 600 more. Additional foreign sales could push the total well beyond 4,000.

The first F-35s will become operational in 2012 when the U.S. Marine Corps fleet is declared ready for combat. The airplane will then go into active service with the U.S. Air Force in 2013, the British air force and navy in 2014, and the U.S. Navy in 2015. By 2014, Lockheed Martin will be producing F-35s at a rate of an airplane a day.

Of course, the fact that Lockheed Martin will be manufacturing thousands of airplanes doesn’t give it a pass in terms of quality. Precision assembly is essential if the Lightning II is to function as designed. Because of its radar-evading stealth requirements, the outer mold lines of each F-35 must be exact, external steps and gaps in the plane’s carbon-fiber outer panels must be virtually nonexistent, and a variety of proprietary coatings must be applied with extreme precision and uniformity. The packaging of the plane’s internal systems is also extremely dense and intricate.

Ultimately, success for the F-35 will be the result of efficient, effective assembly processes as much as the airplane’s inherent performance capabilities.

Wherever necessary, Lockheed Martin is using adjustable work platforms to provide easy access to work areas without damaging the F- 35’s high-tech “stealth” surfaces. Photo courtesy Lockheed Martin Corp.

All Together Now

To meet these demands, Lockheed Martin is employing a host of technologies and disciplines-some old, some new-to make sure everything comes together as planned.

For example, the F-35 is the first aircraft to have been designed entirely using 3D solid modeling software, with digital data shared across the entire F-35 team to assure consistency and precision. In practice, the various design tools used refer directly to a unified digital model. As a result, all parts are exact in their dimensions and fit together accurately.

Already, this approach has proved its worth by smoothing out many of the kinks that traditionally bedevil new aircraft programs in their early stages.

“The speed and precision of assembly on this airplane continues to impress even the most experienced veterans among us…. It far exceeds any program that has gone before it,” says Lockheed Martin F-35 program manager, Dan Crowley. “The ease with which this aircraft has come together, along with the quality of the fit and finish, is simply unprecedented in a first-off-the-line aircraft. It puts us down the path toward meeting our affordability goals.”

Lockheed Martin is also employing this kind of commonality with the project’s physical tooling-a necessity given the modular nature of the airplane and the fact that total manufacturing time for each aircraft will be around 7 months, compared to well over a year for current-generation fighters.

Each production site, whether in North America or Europe, uses similar or identical production equipment, so that the quality of the finished products will be the same, regardless of their point of manufacture. This includes machines like a flexible overhead gantry system, which mills the inside surface of the F-35’s composite skin to ensure the aircraft’s outer form is exact, ensuring correct stealth performance. The machine is accurate to within 50 microns.

Another machine, a forward-fuselage autodrill cell, operates 24 hours a day, 7 days a week to ensure the F-35 meets its ultimate production and quality goals. The system’s two oversized autodrills have already drilled and countersunk thousands of wing fastener holes with zero defects.

Inspection of the F-35’s carbon-fiber wing skins and other composite components falls to what Lockheed Martin calls its Laser Ultrasonic Technology machine (Laser UT), a laser-based system designed to detect imperfections, such as bubbles, inclusions or delaminations, that would cause a part to be rejected. Laser UT inspects parts at a rate that is 10 times faster than current water-coupled ultrasonic inspection machines.

Lockheed Martin is also using a number of laser trackers to facilitate mating of larger components, like fuselage sections and wing subassemblies. This approach almost completely eliminates the need for hard tooling, which in turn reduces cycle times and cost.

Throughout-and especially in the airplane’s wing-assembly stations-the company is employing adjustable work platforms that compensate for the height of the work at hand. These mobile platforms enable workers to perform tasks without stooping or bending.

Moving the large component pieces from station to station in the Forth Worth plant is a small fleet of robot-driven, battery powered automated guided vehicles. Each vehicle has a 35,000-pound load capacity and is equipped with obstacle-detection sensors to prevent collisions.

Lockheed Martin and its partners employ common tooling and design software to ensure close fit of the thousands of the components that make up each airplane. Here, workers at the Lockheed Martin Palmdale, CA, plant install an engine in a vertical-takeoff variant of the airplane. Photo courtesy Lockheed Martin Corp.

Lining Up

At the heart of all these processes and partners will be an “old fashioned” moving assembly line, the first to be used to assemble a modern fighter since the Korean War era. Lockhead Martin anticipates adopting this approach will increase production efficiency, reduce floor space and avoid an estimated $300 million in expenses over the life of the program.

In January 2004, representatives from Lockheed Martin, Northrop Grumman and BAE Systems all met in Fort Worth to collaborate on a preliminary plan for the moving line. Using a full-scale F-35 model, the team simulated the installation of various aircraft systems as the jet crept along an imaginary track. The team also met with manufacturing experts from the automobile industry to tap into their decades of experience in this area.

In addition optimizing material flow and balance, Lockheed Martin believes the line will help force assembly problems to the surface, so that they can be identified quickly and fixed.

This has already been the case at Boeing Co. (Chicago), which uses a moving line to assemble the 737 commercial jet at its plant in Renton, WA. Complementing the automated tow vehicles that slowly pull each aircraft from beginning to end, Boeing has installed a series of coded lights that immediately signal to the entire plant where and when a stoppage has occurred. Although largely psychological, the effect has been dramatic-tying together the hundreds of operators on the floor into a team, promoting a healthy level of both cooperation and competition throughout the line.

“The last time this plant saw a moving assembly line, it was pumping out B-24s at tremendous rates during World War II,” Burbage says. “Since then, the moving-line concept has been greatly refined…. [Using the line] is simply following an established path of product advancement.”

Final assembly of the F-35 has proved remarkably trouble-free, thanks to the use of digital design technologies that ensure the program’s many partners are building their various components to the same high standards. Photo courtesy Lockheed Martin Corp.

Automation and the Environment

Finally, Lockheed Martin is employing automation and “green” technologies to cut costs and minimize the environmental footprint of its production activities.

Attached to the Fort Worth plant is an 82,000-square-foot Component Finish Facility, employing both human operators and robots to precisely apply coating materials to the F-35’s various external components. The facility includes five multipurpose finish rooms and two robotic finish rooms, along with dedicated control and support areas.

Lockheed Martin is also reducing the amount of cooling water that is uses by 40 percent and taking steps to improve its already rigorous air-quality standards.

The plant’s HVAC systems, which maintain critical temperature and humidity conditions inside the building, extract up to 10,000 gallons of water per day, which is then recycled in a nearby cooling tower. By using volatile-organic-compound-free coatings whenever possible along with a high-efficiency air-filtration system, the company is able to remove more than 99 percent of particulate emissions generated by the facility.

The end result of all this foresight and planning is an assembly program that is proving to be reliable and efficient from the outset, as opposed to one requiring months or even years of fine tuning and debugging.

For example, in March 2005, just days after the first F-35 rolled off the line, engineers and technicians were deeply involved in checking the plane’s fuel system. The tests included methodically filling, measuring, weighing and emptying each internal tank with jet fuel, leading up to filling all tanks at operational pressure. The air-refueling system also was checked for correct function. Throughout the testing process, the fuel system proved to be free of leaks-a nearly unprecedented achievement for a first-article aircraft of this sophistication.

“Fuel leaks are a typical problem for a modern high-performance fighter, so this success is an early indication the F-35 is a solid design and a well-built fighter aircraft,” says Doug Pearson, vice president of the F-35 Integrated Test Force. “The F-35 is a stealthy aircraft built with very tight tolerances, and it is remarkable that during the entire comprehensive fuel system testing there were no external leaks from any of the fuel tanks.”

Similarly, flight-testing, begun in late 2006, has shown the airplane to be remarkably airworthy at this stage in the development process. Of 19 test flights, 16 returned “code one.” In other words, the F-35 reported no major problems and was ready to return to the air immediately. Partly as a result, the second F-35-a short-takeoff, vertical-landing version-has entered final assembly with even higher quality metrics than the first airplane.

“We are taking the collective manufacturing know-how of three of the most advanced-technology aerospace companies in the world and focusing it all on the F-35,” Burbage says, summing up the program’s successes to this point. “Each company brings its own set of unique skills that are combining to produce the most efficient manufacturing process ever applied to a fighter jet.”

Ultimately, the F-35’s all-digital design-with essentially no variation from the digital model to the assembled parts-is nothing less than revolutionary in terms of heightening the quality and reliability of the end product, Burbage says. In essence, Lockheed Martin has found a way to push the envelope without even taking to the air.