Lockheed Martin [LMT] on Monday said that Michele Evans, the company’s executive vice president of its Aeronautics segment, is taking a temporary leave of absence to deal with health issues and that Gregory Ulmer, who oversees the F-35 fighter program, will be acting head of the segment until Evans can return to her duties.

Ulmer’s appointment to his additional duties is effective December 1.

A company spokesperson told Defense Daily

after our deadline that “Evans was diagnosed last year with a non-COVID related medical issue and continues to undergo treatment. Her condition is treatable, and a full recovery is expected.” The spokesperson added that “Michele is a critical member of the Lockheed Martin family, and we are supporting her every step of the way as she focuses on her treatment and recovery.”

Aeronautics is Lockheed Martin’s largest segment and is expected to tally about $26.2 billion in sales this year. The F-35 is Lockheed Martin’s largest program.

Evans, who is in her mid-50s, was appointed to lead Aeronautics in October 2018 after serving as deputy executive vice president of the segment.

Ulmer became vice president and general manager of the F-35 Lightning II program in March 2018. Previously, he was in charge of F-35 aircraft production. He will continue to lead the F-35 program while serving as acting chief of Aeronautics.

The Aeronautics segment oversees the range of Lockheed Martin aircraft programs including the F-35, F-22 and F-16 fighters, C-130 airlifter, other aircraft programs, and the venerable Skunk Works advanced development projects.