Sikorsky has reinstalled the transmission into its X2 advancing blade concept demonstrator following detection of a gearbox manufacturing problem during ground tests in December, just before a flight that is designed to reach 150kt (278km/h).
The LHTEC T800 turboshaft-powered counter-rotating coaxial pusher is expected to take flight again in March from Sikorsky's West Palm Beach test site in Florida after a series of ground tests are completed.
Since the first flight in August 2009, the aircraft has flown seven times up to December, achieving a maximum forward speed of 106kt. Sikorsky chief test pilot Kevin Bredenbeck says he experienced "no vibration" on at 106kt and the aircraft's active vibration control system was not yet required.
© Ahsish Bagai/Sikorsky
After duplicating some earlier test points after the initial check flights, Bredenbeck plans to progressively push the speed up to 250kt before the end of the year.
While ground tests continue, Sikorsky flight-test engineers and pilots are practising high speed flight test monitoring processes using an S-76 to simulate the X2 and a Cessna Conquest twin turboprop as a video chase aircraft.