Specifically, the test version of the fighter with the ordinary takeoff (F-35A CTOL) and short takeoff and vertical landing (F-35B STOVL) were marked "stall with a wing at transonic flight and greater than expected sideslip angles of attack on the middle" . The report also noted that some components of the airplane were the least reliable than discussed in the technical documentation.
In addition, during the flight of the F-35 engine with Pratt & Whitney F135 afterburning, has been observed instability of air flow in the afterburner, because of what began noticeable vibration. In addition, under the described lack of engine was unable to go full throttle when the afterburner. Because of the identified problem the company Lockheed Martin, which creates F-35, was required to set aside a few tests. At the current time, designers try to remove this deficiency.
The report DOTE also highlighted problems helmet information display F-35, although their nature is not disclosed. According to the document, the defects will be corrected when fighter have installed the software and flight control tasks version of Block 2. At the current time are tested with the F-35 Block 0.5 software versions and Block 1. Unlike most of the other fighters, F-35 has no head-up displays, and all the basic information is displayed on the helmet-mounted display.
In its own report also recommended DOTE Lockheed Martin conduct preparatory tests Block 3 software on the simulator F-35, since the available test sites do not allow vsepolnotsennuyu verify the operation of all systems of the fighter. Namely, test on-board detectors in ordinary flight has a distance limitation.
Engineers are also invited to the configuration in the design of on-board inert gas generating system (OBIGGS), whose main task is to fill the expiring seats in the fuel tanks of neutral gases. Due to this reduced percentage of oxygen in the tanks to prevent fire or explosion of fuel. During the tests, it was seen that OBIGGS not always able to provide a supply of inert gases in the fuel tanks.
Previously, it was clear that Lockheed Martin redesigned one hundred percent of duralumin parts F-35B, located in the place where the main landing gear mounted to the frame plane. During the last test revealed that as a result of several landings this piece started to crack. Recently, the problem element on the F-35B will be replaced and the test aircraft will last.
January 11, 2010 U.S. Secretary of Defense Robert Gates announced that proclaimed the F-35B trial period of two years, after which the aircraft project will be closed if Lockheed Martin fail to cope with the deficiencies found. Gates said that in the current time F-35B STOVL, are created for the U.S. Marine Corps, "experiencing severe difficulties with the tests," because of what the price of the aircraft could grow substantially. If the problem does not turn away, the Pentagon will end funding for the project F-35B.
Lockheed Martin wants to release three versions of a promising fighter Lightning II — F-35A CTOL, F-35B STOVL and F-35C CV (carrier-based version). In purchasing these fighters are interested Air Force, Marine Corps and Navy, respectively. In total, the United States adopted in 2473 is planned to take such aircraft. As expected, the first fighter will be adopted in 2016, but according to the latest estimates, this deadline may be postponed to a later time.