Nine of the original 14 F-35 flight test aircraft have flown after the debut on 6 July of the fourth conventional take-off and landing (CTOL) variant, known as AF-3.

The 42min sortie began at 18:20, local time, outside Lockheed Martin's final assembly plant in Fort Worth, Texas, with company test pilot Bill Gigliotti at the controls. Area storms stopped the flight short, Lockheed says.

After first flight of the fourth short take-off and vertical landing (STOVL) variant BF-4 in April, AF-3's entry into the flight test programme means two aircraft are now dedicated to mission systems testing.

 F-35A AF-3 flight
© Lockheed Martin

Mission systems onboard the F-35 include the Northrop Grumman APG-81 radar, electronic warfare suite, distributed aperture system and electro-optical targeting system.

First flight of AF-3 had been expected several weeks ago. Lockheed attributed at least part of the delay to several components that failed at temperatures below specification.

Since February, a programme restructuring has added three more aircraft to the flight test programme, including one developmental F-35 carrier variant and two STOVL variants borrowed from operational units.

Separately, Lockheed is to receive a contract worth around $522 million to acquire long-lead items for the JSF programme’s fifth low-rate initial production phase. This is expected to comprise 42 aircraft for the US armed services: 22 CTOL; 13 STOVL and seven carrier variant F-35Cs.

Source: Flight International