PAUL LEWIS / NASPATUXENT RIVER
The Bell Boeing MV-22 Osprey returned to flight on 29 May after an 18-month grounding following two fatal crashes. The flight is the start of a restructured development test programme that the US Navy Air Systems Command (Navair) hopes will culminate in the delivery of a first production configured Block A tiltrotor to the US Marine Corps by the end of next year.
This follows an exhaustive approval process to ensure flight safety deficiencies identified by several high-level investigations were addressed before the V-22 flew again. "This has led to one of the most comprehensive reviews in recent times," says Col Dan Schultz, Navair V-22 programme manager.
Three independent reviews were conducted of the hydraulic system and flight control system (FCS), and four Navair/US Air Force reviews of electrical, fuel, digital engine control and drive systems. A total of 7,800h has been focused on the FCS, with 1,700h in Boeing's triple integration laboratory for regression testing and developing emergency procedures.
As well as new FCS software, over 500 changes have been made to the 345 bar (5,000lb/in2) hydraulic system, including the rerouting of pipes, separating lines from electrical bundles and improving clamps to prevent abrasion and rupture.
Engineering and manufacturing development (EMD) aircraft 10 made the 1.5h first flight at Patuxent River. It will also be used for aeromechanical testing, including the pitch-up sideslip and lateral role on deck. The first flight included helicopter mode operations and a transition to aircraft mode.
Aircraft 8 will start a year of critical vortex ring-state testing in August, with the major challenge being the high rate of descent testing, says Schultz.
The two EMD aircraft will be supplemented by five modified low rate initial production V-22s. The second pair of EMD tiltrotors, representative of the USAF's planned CV-22 configuration, will begin flying in September at Edwards AFB and will be joined by two production representative test vehicles. Testing will concentrate on Blocks 0 and 10 mission systems, such as the radar and defensive systems.
The first fully modified Block A MV-22 is due to fly in the middle of next year and will be used for initial operational testing before the lead USMC squadron resumes flying. A second full operational evaluation and validation is planned for 2004 leading to an initial operational capability by 2005.
Source: Flight International
