EVERETT — They’re the creme de la creme of the Boeing Co.’s engineers and scientists.

They’re the go-to minds that Boeing turns to when the company is in trouble.

And they’re the group that propels Boeing into the future.

Boeing’s Technical Fellowship program includes less than 5 percent of the company’s scientists and engineers. But the fellows represent much of the engineering talent that has given the company its edge.

“The success of the Boeing Co. over the years really has depended on engineering,” said Jim Albaugh, president of Boeing Commercial Airplanes, in a recent interview.

But, with an aging work force, the company and its engineering union are concerned about how Boeing will sustain its well-cultivated, highly experienced engineering minds, like those in the fellowship program. More than 56 percent of Boeing engineers are 50 years old or older. They’re eligible for retirement at age 55, though the average retirement age for Boeing workers is 62.

“We have a fear that if the aging work force isn’t paid attention to, we could wake up and find we’ve lost some critical skills,” said Bill Dugovich, communications director for the Society of Professional Engineering Employees in Aerospace.

Engineering is not a job that one becomes an expert at overnight. Mike Delaney, vice president of engineering for commercial airplanes, estimates it takes at least five years for a new engineer to become “high value.”

“At that point, they’re leading and driving product,” he said.

It takes longer, 12 to 20 years total, to lead an engineering team, and 15 to 20 years minimum to be a chief engineer. Those engineers, like the technical fellows, are essential in sharing knowledge with the younger generation, Delaney said.

Tanni Sisco, a 20-year employee with Boeing, joined the Technical Fellows program two years ago.

“It’s been a fabulous opportunity for finding mentors,” she said. “There’s so much to learn.”

Sisco, 47, looks to Jim Buttrick, who has more years in the fellows program, for mentoring. The two devised processes and tools that will make it possible for Boeing to assemble 10 of its 787 Dreamliner jets monthly. The process created by Sisco “could, would, and has enabled automation” on Boeing’s new 787 jet. She collaborated on it with Buttrick, who is responsible for creating a flex track drill. Buttrick’s tool vacuum-attaches to a jet fuselage or wing and drills precise holes in the surface.

Advances like these make Boeing Technical Fellows influential within the company. But most are recognized outside Boeing as well for their published research or patents. Buttrick alone holds 32 patents.

The technical fellowship program was created in 1989 for Boeing engineers and scientists who aren’t seeking management positions. Delaney expects the fellows to mentor younger engineers as they tackle major projects or problems out on the floor.

That’s fine by Buttrick, who sees the value in nurturing younger engineers — both those in the fellowship program, like Sisco, and those years from applying to be in the program. His coaching includes teamwork, skills development and career advice.

Over the years, Buttrick has watched the company lay off talented, trained young engineers during down times in the cyclical aviation business. And, through the outsourcing that took place on the 787, he’s seen some of the newer engineers be charged with helping Boeing’s global 787 suppliers get back on track.

“We never had the experience this group is getting now with this model,” Buttrick said.

The outsourcing and layoffs are problems that Boeing’s Albaugh knows need to be addressed. The company hopes to keep its work force level steady to avoid laying off engineers and Machinists that the company will need down the road as workers retire.

“We’ve outsourced a lot of engineering,” Albaugh said. “I think we’ve outsourced too much.”

Boeing’s Delaney is in the process of evaluating which core competencies the company will retain in the future. The company is doing more of its own engineering for the next Dreamliner model, the 787-9, than it did on the initial one, the 787-8.

Despite some of those past troubles, Albaugh believes Boeing is a company that continues to attract top talent, partly because of the opportunities it provides. In just the next few years, Boeing will be working on the 787-9 and the 747-8 passenger plane, as well as looking at either replacement aircraft or enhancements for its 737 and 777 jets.

“I can’t think of a more exciting time to be an engineer,” Albaugh said.