Lockheed Martin delivers 500th F-35

March 3 (UPI) -- Lockheed Martin announced Tuesday that it, along with the F-35 Joint Program Office, has delivered the 500th F-35 aircraft.

The 500th aircraft is a U.S. Air Force F-35A intended for the Burlington Air National Guard Base in Vermont, the contractor said in its announcement of the program milestone.

The new aircraft is one of 354 F-35A conventional takeoff and landing variants, 108 F-38B short takeoff/vertical landing variants and 38 F-35C carrier variants used by the U.S. and partner militaries.

"These milestones are a testament to the talent and dedication of the joint government, military and industry teams," said Greg Ulmer, Lockheed Martin, vice president and general manager of the F-35 program. "The F-35 is delivering an unprecedented 5th Generation combat capability to the warfighter at the cost of a 4th Generation legacy aircraft."

The milestone comes amid news that nearly 85% of the engines ordered for the F-35 last year were delivered past their deadlines as Pratt & Whitney struggled with parts and suppliers.

According to Bloomberg's reporting on a Pentagon report, last year 85 percent -- or 128 of 150 -- engines ordered for the next-generation F-35 were delivered past deadline as Pratt & Whitney struggled with parts and suppliers.

The aircraft has also been plagued by problems with function, a gun that doesn't shoot accurately and shortages in its supply chain -- issues arising ahead of a decision on whether to move into full-rate production on the $428 billion program.

A statement from Pratt & Whitney said the contractor had "exceeded its annual F-35 engine delivery commitment" in 2019 and "remains laser-focused on working closely" with the program office to achieve on-time delivery this year.

This week the Air Force also announced that the F-35 program has its first female demo team commander and pilot.

Capt. Kristin "BEO" Wolfe took over as the new F-35A Demonstration Team's pilot and commander for the 2020 and 2021 air show season last week, according to a press release from Utah's Hill Air Force Base.

Wolfe, who had served as an instructor pilot for the 388th Fighter Wing, was certified during the Air Force's Heritage Flight Training Course at Davis-Monthan Air Force Base in Arizona.

The F-35 Lightning II Joint Strike Fighter -- a single-engine stealth multirole combat aircraft used by the U.S. Air Force, Navy, and Marine Corps -- is considered the most advanced fighter aircraft in the sky, but also a major driver of the Pentagon's budget.