The US Marine Corps plans to begin test flying a Bell-Boeing V-22 Osprey equipped with modified flight control software, designed to rectify lateral control problems discovered during recent sea trials. The Corps claims that a software fix is in hand for the tiltrotor's automatic jettison system.
Programme engineers are making software revisions to augment the V-22's automatic flight control system (AFCS) and to reduce pilot workload when operating from warship flightdecks. To avoid overloading the AFCS, some other functions have been re-allocated elsewhere.
"Modifications will be complete in less than two months," says the V-22 programme office at Patuxent River naval air station. "The software has already been tested with good results in the simulator. Testing of the software in the aircraft is expected in May or June."
The problem of lateral axis control in high wind was highlighted during a month-long series of sea trials in January, conducted from the helicopter carrier USS Saipan. During one of 350 landings performed, the V-22 crew waved off from landing on the carrier as the tiltrotor transitioned to the hover in a 22kt (40km/h) wind at the end of its approach.
Forward flight external load testing of the V-22 is expected to recommence shortly following demonstrated improvements to the Forward Cabin Control System (FCCS) as the result of software changes. The V-22 Integrated Test Team, together with industry, has reviewed the FCCS design and conducted hangar and hover flight testing of the system.
External loads, including automatic or pilot commanded jettisons, are governed by the FCCS. It has experienced "problems during developmental tests, which have slowed the progress of external loads testing", according to the programme office.
The focus of V-22 testing has switched to the Naval Air Warfare Centre at China Lake, California, where ballistic survivability testing is being conducted. This entails firing live ordnance at a test vehicle. "Although we'll be putting a lot of holes in this aeroplane, the end result will save a lot of lives in the future," says Joe Manchor, V-22 test engineer.
Elbit Systems subsidiary EFW, in the meantime, has delivered the first active matrix liquid crystal display (LCD) to Boeing for installation on the V-22. The LCDs will replace the cathode ray tube based displays now employed in the tiltrotor's cockpit.
Source: Flight International
