The F-35 Joint Strike Fighter fleet still does not have an adequate aircraft availability rate, according to the Defense Department's testing office.
The fifth-generation fighter has had a "flat" trend in capacity rates over the past three years, according to a recent Director of Operational, Test and Evaluation report. Even as the services focus on improvement initiatives, they're "still not translating into improved availability," it stated.
"Fleet-wide average availability is below program target value of 60 percent and well below planned 80 percent needed for efficient conduct of [Initial Operational Test and Evaluation, or IOTE]," the 2018 DOT&E report said. Bloomberg was first to report the news.
The earliest lots of the Corps' F-35B variant have proven to have a shorter-than-expected service life.
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The "early-production F-35B aircraft [are] well under the expected service life of 8,000 flight hours, and may be as low as 2,100 flight hours," the report states.
If the short-takeoff-and-vertical-landing jets are not appropriately upgraded, it could mean their flight hours will hit the limit by 2026, officials said.
In a statement sent to Military.com Friday afternoon, Lockheed said the company is committed to achieving the 8,000-hour mark.
"Planned modifications and fleet management of the early contract F-35B aircraft will ensure that they meet the 8,000-hour service life requirement, and aircraft delivering today incorporate these design changes in the build process to ensure they'll meet 8,000 hours or more," the company said in a statement.
The DOT&E office said it will monitor progress through the Joint Program Office.
"The F-35 Joint Program Office will continue to use Individual Aircraft Tracking (IAT) of actual usage to help the services project changes in timing for required repairs and modifications, and aid in Fleet Life Management," DOT&E said.
Meanwhile, the Air Force's F-35A variant has not met the office's standards for its internal GAU-22/A cannon, assessors said.
"Based on F-35A gun testing through September 2018, DOT&E currently considers the accuracy of the gun, as installed in the F-35A, to be unacceptable," the report states.
The gun has suffered from issues that "result in muzzle alignment errors" as well as "unsafe gun" cockpit alerts.
Asked about the report Friday, Lt. Gen. Arnold Bunch, the service's military deputy for the Office of the Assistant Secretary for Acquisition at the Pentagon, said that top leadership is putting more emphasis on the program as they continue to work with the Joint Program Office and manufacturer Lockheed Martin Corp.
Bunch, who has been nominated to pin on his fourth star and take over Air Force Materiel Command, said the goal is to reach the "80 percent mission-capable rate" set by then-Defense Secretary Jim Mattis in October, at least for combat-coded aircraft.
"We are working a lot of different initiatives," he said at an Air Force Association breakfast in Washington, D.C.
"We are working a lifecycle support plan right now" with JPO and Lockheed, he said, adding that the plan differs greatly from earlier ones but refusing to elaborate because it's "still in review."
"We're setting timelines and calendars for when we're going to get to timelines, dates, milestones to get things done, so that we're seeing that we're getting the performance improvements that we are anticipating," Bunch said.
Mattis wanted the services to increase mission-capable rates for the F-35 fleet and other premier fighter jets to more than 80 percent in a single year, requiring the Air Force and Navy to boost maintenance and sustainment for dozens of fourth- and fifth-generation aircraft.
Bunch said the Air Force and DoD as a whole are "pushing for" that 80 percent rate. "It's a challenge, but that's the goal we're at," he said.
In a statement, a spokesman for Lockheed said said the company has been communicating with the services to achieve a better fleet-wide mission-ready status.
"With enhanced reliability, newer aircraft are now averaging greater than 60 percent mission-capable rates with some operational squadrons near 70 percent," the statement said.
"While we await the full details of the ongoing Operational Test phase, we are actively enhancing all aspects of the F-35 to ensure it exceeds warfighter demands and outpaces evolving threats. Items identified in the Annual DOT&E report are well understood and have been resolved in partnership with the F-35 Joint Program Office or have an agreed path forward to resolution," it added.
The JSF program, expected to cost $1 trillion over its lifetime, is continuing its formal operational test phase, which it entered in December.
The JPO and Lockheed announced Dec. 6 that all three F-35 variants belonging to the Air Force, Navy and Marine Corps will be field-tested "for the purposes of determining the weapons systems' operational effectiveness and operational suitability for combat."
The IOT&E testing is expected to be complete late this summer, the JPO said.
Editor's Note: This story has been updated with comments from Lockheed Martin about the DOT&E report.