V-22 Returned to Flight
Finally, the V-22 has been cleared to return to flight. Details are few except that the problem was in the proprotor gearbox. Over the 30+ years of operation this gearbox has shown excellent reliability and no crashes have been attributed to it in over 750K flight hours, I can now see why it has taken so long to study this accident and why they stressed a material failure and not a design issue. The only problem I recall with the proprotor gearbox was due to maintainers using power washers to clean the outer gearbox of Mideast grime against the established practices. This resulted in corrosive cleaning fluid being blown past the mast seal and contaminating internal bearings and gears. If a corrosion pit is the ultimate source of this failure a plausible cause may be obvious.