A year of flight testing has led to a reversal of fortune for the V-22, with senior Pentagon officials giving their blessing to take the tiltrotor into a higher production rate.

The Bell Helicopter Textron and Boeing-built V-22 has been under intense scrutiny since December 2000 when flight testing was halted because of two fatal crashes that year in which 23 Marines died. Flight testing under a completely revised program resumed only a year ago, with developers under pressure to show they could fix reliability problems and demonstrate the tiltrotor is safe to fly. Otherwise, senior Pentagon officials said, the program would be killed. In the intervening period, production of V-22s would be limited to 11 aircraft per year.

Testing, including more than 460 flight hours, has won over at least those critics that matter. Pentagon acquisition czar E.C. (Pete) Aldridge, a self-proclaimed V-22 skeptic, last week reviewed the program and lauded the technical progress demonstrated during the flight test phase and gave the nod to move the program forward more aggressively. The V-22 verdict was one of Aldridge's final actions in that post; he retired Friday.

High-rate-of-descent (HROD) evaluation of the V-22 has been a focal point of testing in recent months, particularly because one of the crashes in 2000 was linked to HROD-induced vortex ring state (VRS), a blade stall condition. The pilot of the V-22 descended too rapidly at low forward air speed, causing VRS and aircraft roll that wasn't recoverable. HROD-related VRS has become a battleground for detractors and supporters of the V-22, with critics charging the flight instability makes the aircraft inherently unsafe and advocates countering that the tiltrotor is less susceptible to the condition than regular helicopters and that control can be regained simply by moving the nacelles forward.

The test program was able to dispel two of the main questions, that the V-22 handled poorly at low speeds and that the aircraft is unsafe because of VRS, said Marine Corps Commandant Gen. Michael W. Hagee. There are still technical hurdles to clear, such as demonstrating the tiltrotor's deicing capability, he noted. That is planned for this winter.