The Bell Boeing MV-22 Osprey has been given a qualified stamp of approval by the US Marine Corps operational evaluation (Opeval) report, leaving a number of deficiencies still to be rectified before the tiltrotor can be cleared for a full-rate production decision.
The Opeval report concludes that the MV-22 is operationally effective and suitable for land-based operations, but that suitability for ship-based operations remains unresolved due to additional evaluation required on the system designed to stow and fold the proprotors and wing, says Col Nolan Schmidt, USMC V-22 programme manager.
Schmidt says reliability problems with the stowage system had been identified earlier, and modifications have already been demonstrated on a production aircraft. The tiltrotor is due to conduct further sea trials in mid-November, ahead of an end of month decision on full production.
Changes to the stowage system include enlarging the locking pin targets and reducing the timing of the stowing sequence. The MV-22, despite meeting a threshold 17h mean time between mission abort rate and 15h mean time between critical failure, fell 50% short of the 1.4h overall component mean time between failure.
Nolan claims that the latter is a new measure against which the MV-22 is the first aircraft to be measured. He adds that 149 corrections have been identified of which 122 have been incorporated and the remainder will be addressed during follow-on test and evaluation with the aim of being in place by early 2002.
Attention will now focus on some of the 22 earlier waived requirements such as the incorporation of a chin-mounted self-defence gun and an extensible rescue hoist and changes to swash plate actuators now in qualification. The MV-22 is scheduled to make its first operational shipboard deployment in late 2003.
Source: Flight International
