Pratt & Whitney has resumed ground tests of the F135 engine for the short take-off and vertical landing (STOVL) Joint Strike Fighter with the lift fan inlet installed.
Testing was interrupted in May when deliberate stalls of the lift fan broke the drive shaft and damaged the engine.
The F135 is being tested with the simulated inlet installed to check how air flows around the angled door and into the lift fan.
P&W says initial testing confirmed that the F135 with the Rolls-Royce lift system will meet or exceed thrust requirements for the STOVL F-35.
Ground runs of the F135 with the lift system, including shaft-driven lift fan, roll posts and three-bearing swivelling nozzle, are under way at P&W's West Palm Beach, Florida, test site. The company is also building the first three STOVL flight-test engines.
The first STOVL F-35B is in final assembly at Lockheed Martin in Fort Worth, Texas, and is scheduled to fly in May 2008.