The U.S. Defense Department’s F-35 Lightning II joint program office plans to modify more than 200 early-production jets to bring them up to newer configurations, the program’s leader said Feb. 28.

Aircraft from Low Rate Initial Production (LRIP) Lots 2 through 8 will receive a mix of hardware and software updates to reflect design improvements that were developed after those aircraft were built, Navy Vice Adm. Mat Winter told reporters. 

Winter said he expects those early aircraft to experience increased reliability after the modifications are finished in early 2019. While the availability rate for the overall F-35 fleet is 51 percent, it is only 40 percent to 50 percent for Lots 2 through 4, compared to 70 to 75 percent for Lots 9 and 10.

“My warfighters asked for 65 to 80 [percent], so I’m meeting that [for the newest jets], but I’m not meeting that right now with my earlier aircraft,” Winter said. By modifying the older aircraft, ”I’m bringing them up to snuff as best I can.”

Older aircraft will require more modifications than newer ones. Jets from Lots 2, 3 and 4 will need about 155 hardware changes, compared to only about 20 for Lot 8 planes.

“Will [the oldest aircraft] be as good as a Lot 10? Most likely not because they have seven, eight years of wear and tear on them,” Winter said.

Deliveries of the newest batch, Lot 10, have begun, and Winter’s team is negotiating a Lot 11 contract with prime contractor Lockheed Martin [LMT]. Production is slated to increase from 66 aircraft in Lot 9 to 105 in Lot 10 and 130 in Lot 11.

To help ensure that the program meets its goals for increased production rates, Winter is pushing to reduce quality problems, such as parts that do not fit correctly and need to be reworked, or dings that occur on the assembly line.

A quality glitch “slows things down,” Winter said. “We want to reduce the scrap-repair-rework incidents so that we can more agilely and more effectively move aircraft down the production line.”