The Pentagon’s F-35 Joint Strike Fighter fleet has accumulated over 100,000 flight hours as development of the stealthy new fighter approaches the finish line.

Contractor Lockheed Martin expects that it will complete development work on the full Block 3F configuration by the end of the year. Delivering the full Block 3F would complete the requirements set forth under the System Development and Demonstration (SDD) contract that was originally awarded to Lockheed in 2001.

“This 100K milestone marks a significant level of maturity for the program and the F-35 weapons system,” Lockheed Martin executive vice president and F-35 program general manager Jeff Babione said in a statement.

“We are well positioned to complete air vehicle full 3F and mission systems software development by the end of 2017.”

lockheed, the company and the F-35 integrated test force still have to validate the final release version of the Block 3F software—which is arguably the most important remaining task.

Testers will have to do additional testing on the short takeoff/vertical landing (STOVL) F-35B for operations at austere sites and ski-jump operations. The latter is a requirement for operations onboard Britain’s Queen Elizabeth-class carriers, which are not equipped with catapults and arresting gear.

Flight testers will also have to complete high-Mach loads testing for both the F-35B and F-35C carrier variants for the flight sciences portion of the flight tests. They will also have to and completion of the remaining weapons delivery accuracy tests.

Major SDD fleet test milestones in recent months include:

- Completed testing for the F-35A’s final envelope involving high risk ‘edge of the envelope’ maneuvers, stressing the aircraft to its limits in structural strength, vehicle systems performance, and aerodynamics while proving excellent handling qualities.   

- Completed all U.K. Weapon Delivery Accuracy tests for the AIM-132 ASRAAM and Paveway IV weapons, and completed 45 of 50 SDD Weapon Delivery Accuracy tests including multiple target and multiple shot engagements as well as internal gun and centerline external pod 25mm gun accuracy tests.

- Performed multi-ship mission effectiveness tests, such as Offensive Counter-Air and Maritime Interdiction, demonstrating the performance of the F-35 System.

The F-35 has been operational with the United States Marine Corps since July 2015 and became operational with the United States Air Force in August 2016 with interim Block 2B and Increment 3i software respectively. The U.S. Navy is expected to declare its F-35C variant operational in 2019. The Pentagon hopes to eventually buy 2,443 F-35 fighters in total.

Dave Majumdar is the defense editor for The National Interest. You can follow him on Twitter: @Davemajumdar.

Image Credit: Reuters.