WASHINGTON - On Wednesday, the F-35 Joint Strike Fighter conducted its final development flight test, effectively ending the development phase of the project 11 years after the aircraft first flew in 2006.

The F-35 manufactured by Lockheed Martin will now enter operational testing and evaluation conducted by the Pentagon’s Independent Test Office. Once completed, the system development and demonstration (SDD) part of the plan will be officially completed and the F-35 will enter full-speed production.

Lieutenant General Matt Winter, executive officer of the F-35 joint program, said at the Naval Alliance Sea and Air Conference on Wednesday that he expects to complete the final SDD flight test this week, "it may even be completed today... This is an important milestone in the plan."

The test site-the Navy test aircraft CF-2 carrying 2,000 pounds of GBU-31 joint direct attack ammunition and AIM-9X Sidewinder missiles as external payloads while collecting data-took place on April 11 in Patuxent River, Maryland Naval Air Station.

Throughout the test plan, JPO was responsible for “over 9,200 sorties, more than 17,000 flight hours accumulated, and more than 65,000 test points performed to verify the design, durability, software, sensors, weapons capabilities and performance of all three F . -35 variant," Winter said in a statement on Thursday.

During the SDD project, the project completed more than 1,500 vertical landing tests of the Marine Corps F-35B short-range takeoff and vertical landing modification, and conducted 6 phases of sea trials on the F-35B and F-35C aircraft carrier modification.

It also conducted 183 weapon separation tests and 46 weapon delivery accuracy tests, as well as 22 mission effectiveness tests. These tests measure the F-35’s ability to withstand advanced threats in multi-ship engagements with up to 8 joint strike fighters. JPO said in a statement.

On April 11, 2018, an F-35C test aircraft CF-02 landed at Patuxent River Naval Air Station in Maryland after completing the final development test flight. (F-35 Joint Project Office)

Lockheed Martin's vice president and general manager of the F-35 program, Greg Ulmer, called it "the most comprehensive, rigorous, and safest development flight test program in aviation history."

However, it is not without obstacles. Cost overruns led to Nunn-McCurdy violations in 2010, forcing the Department of Defense to evaluate whether the plan should continue.

Although the JPO has gained better overall control over development, production, and maintenance costs, there are still some notable technical issues, including engine problems that caused fires and prevented aircraft from going to the 2014 Farnborough Air Show and caused The insulation supply defect of some jets will be grounded in 2016.

The latest issue surrounding corrosion of fastener holes has been technically resolved, but the Japan Patent Office and Lockheed are still debating who should pay for the repair work. Prior to this, the Ministry of Defense has been suspending deliveries.

The JPO stated in a press release that although the SDD flight test has ended, the F-35 flight test will continue to be part of the follow-up modernization work, called continuous capability development and delivery, or C2D2.

However, this strategy has also caused some controversy.

When Winter announced the strategy at a national defense press conference in September, he stated that its use of agile software development would help the program continue to adopt new software updates and improvements.

But critics say that C2D2 allows JPO to claim that they have delivered a fully operational jet with 3F software and postpone the repair of minor software defects until later in the program.

Valerie Insinna is an air combat reporter for defense news. She previously worked on Navy/Congress Beat for Defense Daily, and then worked as a writer for National Defense Magazine for nearly three years. Prior to this, she served as an editorial assistant for the Tokyo Shimbun Washington Bureau.