The radar-evading F-35 fighter jet, a nearly $400-billion weapons program under development for more than a decade, is facing its worst turbulence since Washington decided to buy it in 2001 — when it was billed as the most affordable, lethal and survivable military aircraft ever built for the U.S. and its allies.

At a time when federal spending is under a microscope, the plan to develop and build 2,443 airplanes is hundreds of billions of dollars over budget. The F-35, known as the Joint Strike Fighter, has been delayed by glitches in its onboard computer systems, cracks in structural components and troubles with its electrical system.

A two-star general serving as the military’s project manager was fired over the program’s never-ending problems. The Pentagon has delayed orders of the aircraft, and the fighter jet is caught in the middle of a major spending fight in Congress. What’s more, the plane has roiled political debate in Canada, the Netherlands and other allies that are picking up 10% of the development costs.

GRAPHIC: F-35 joint strike fighter

The Obama administration wants to delay the purchase of 179 jets to save $15 billion. But there is pressure to cut more. Next week, the Pentagon’s F-35 program manager is set to testify before the Senate Armed Services Committee.

Although much of the debate is taking place in Washington, the melodrama is being closely watched in Southern California, where much is at stake. Only last week, executives of F-35 maker Lockheed Martin Corp. made an appearance in El Segundo to remind local businesses and aerospace workers that the F-35 will have a huge financial effect in the years to come — pumping an estimated $6 billion into the state’s economy and creating 27,000 jobs.

“The state of California has a huge stake in this,” said Danny Conroy, one of Lockheed’s directors of the F-35 program. “California is the single biggest supplier base for the F-35 in the country.”

Northrop Grumman Corp.is one of 260 companies in California that supply the program — far more than any other state. And the subcontractors are feeling the delays that have plagued many aspects of the F-35.

Northrop, for instance, has 1,665 employees in Palmdale, San Diego and El Segundo working on the program. But it is a fraction of the number of people Northrop had expected to hire by now.

In El Segundo, the company makes 100 parts for the stealth fighter jet. As the second work shift began last week, Northrop manager Chip Oppenlander scanned the vast factory floor and remarked on the dozens of unused workstations.

“I expected things to be much busier by now,” he said, wringing his large hands. “We’ve hired about half as many people as initially planned.”

The Pentagon’s long-term vision is to replace today’s fighter fleets, which have an average age of 22 years. It is centered around a plan to develop one basic fighter plane that could — with a few tweaks — be used on runways and aircraft carriers, and hover like a helicopter for joint use by the Air Force, Navy and Marine Corps.

The one-size-fits-all approach has never been tried before, and when test flights began in 2006, problems soon followed. The flaws have been so complicated and so costly that they have put the program nearly a decade behind schedule. The program’s costs — once estimated at $233 billion — have skyrocketed to about $396 billion, the Pentagon said last month.

Still, the Pentagon remains dedicated to the program, saying the F-35 is vital to national security in the 21st century.

“As part of the defense strategy that the United States went through and has put in place, we have made very clear that we are 100% committed to the development of the F-35,” said Defense Secretary Leon E. Panetta last month after a meeting with Mexican and Canadian military leaders. “We absolutely need it for the future.”

But the drawn-out development is infuriating to some in Congress because the program was sold as a way to maintain costs and shorten the procurement process by avoiding building three planes on three assembly lines.

Sen. John McCain (R-Ariz.) reminded fellow lawmakers of this in December, when he took to the Senate floor to criticize the program.

“The Joint Strike Fighter program has been both a scandal and a tragedy,” McCain said. “We are saddled with a program that has little to show for itself after 10 years and $56 billion in taxpayer investment that has produced less than 20 test and operational aircraft.”

The Pentagon’s latest estimated lifetime costs of the F-35 program — to develop, buy, and maintain the planes over 55 years — topped $1.5 trillion.

Loren Thompson, military policy analyst for the Lexington Institute in Arlington, Va., said the estimate is “made up” because it forecasts what inflation and fuel costs will be decades from now. He adds that it would cost the military three to four times more to keep today’s fighters flying. “Nobody ever explains that to Congress.”

But supporters and critics alike say the escalating price tag represents an inescapable roadblock that Congress must face. The government’s track record is clear: The more a plane costs, the fewer they buy.

The Pentagon’s aircraft procurement efforts have been fraught with cost overruns, delays and cuts. Two decades ago, officials originally wanted 648 F-22 fighter jets for $139 million per plane. Eventually, the military ended up with only 188 at a price tag of $412 million each.

Before that, the Pentagon wanted 132 new B-2 stealth bombers at about $500 million per plane. It ultimately bought 21 at $2.1 billion each.

The cost per F-35, about $161 million, could keep rising and ultimately push it into a death spiral as well.

House Armed Services Committee Chairman Howard “Buck” McKeon (R-Santa Clarita), one of the plane’s strongest boosters in Congress, acknowledged problems ahead.

“History repeats itself,” he said in a recent interview. “At some point, some members of Congress are going to demand that we buy less F-35s. It’s inevitable.”

Subcontractors across California have spent millions of dollars preparing for what is expected to be decades of work on the F-35.

Northrop, for instance, has a new, $170-million assembly line in Palmdale. At the 1-million-square-foot complex, there are robots capable of carrying multi-ton plane sections; high-precision laser cutters; and its very own internal GPS system. It will ultimately be capable of producing one complete fuselage for any of the three F-35 versions without interruption.

The assembly line completed its first fuselage last month and sent it to Lockheed’s Fort Worth plant for final assembly.

“We’re on track now,” said Steve O’Bryan, a Lockheed vice president. “I’m not trying to give this a rosy view or anything: We’ve had our share of development challenges.”

With test flights only about 20% completed, O’Bryan said Lockheed is churning out two F-35s a month and plans to deliver four a month by summer.

Workers find the plane’s ups and downs nerve-racking. Edwin Salas, a bespectacled 49-year-old inspector with Northrop, works with his 27-year-old son on the program in Palmdale. He’s glad that the sections are beginning to be shipped out to Texas.

“We’ve had our hurdles, but things are being ironed out,” he said. “I’m looking to retire on this program. God willing, my son will too.”

william.hennigan@latimes.com