Original URL: http://www.theregister.co.uk/2009/03/27/swashplate_bolt_snag_hits_osprey/

Fresh tech hiccup for V-22 tiltrotor fleet

If something hasn't broken on your Osprey, it's about to

By Lewis Page

Posted in Science, 27th March 2009 13:33 GMT

The famous V-22 Osprey tiltrotor, which flies like a plane but tilts its props upwards to land and take off like a helicopter, appears to have hit yet another technical snag.

The V-22 with rotors tilting

Hey, Joe - is it supposed to make that rattling noise?

The troubled military combo-copter, which suffered through a decades-long and accident-prone development to finally go operational in Iraq last year, has now been subjected to a fleet-wide safety grounding. This followed the discovery of loose bolts rattling about in an engine nacelle on an Osprey after landing at the US air base at al-Asad.

The bolts, according to reports, had fallen out of the "swashplate" in the propellor hub. The swash plate on a helicopter or tiltrotor is used to convey control inputs from the pilot into the spinning rotor disc. Should it break loose, a complete loss of control would result.

After the initial discovery, other Ospreys in Iraq were found to have loosened swashplate bolts and the entire fleet was grounded as a precaution. Initially it was thought that the loose fastenings might have been the result of maintenance failures, but Flight International now reports that at least one further V-22 in America is suffering from the same issue, and that all the affected aircraft are "high-time" ones - that is, ones which have been flown a lot.

While investigations are still ongoing, it appears that the loose bolts syndrome after substantial flight time probably affects all V-22s, and that modifications will be required. Osprey programme chief Colonel Matt Mulhern told Flight that “We’re going to eventually need a material fix for this”.

Mulhern pointed out that it's fairly routine for military aircraft fleets to be grounded temporarily following discovery of tech snags, and that modifications for increased safety are likewise normal.

“This is an event that aircraft go through," he said.

But the Osprey is a favourite hate object for many in America, who consider it an unnecessarily complicated and expensive white elephant. Nonetheless, the US Marines - the main users of the tiltrotor - have structured many of their future plans around the V-22, and have sufficient political clout that it's unlikely to be binned at this late stage.

Even so, with severe pressure on US military spending forecast for the near future and fresh Osprey purchases by the US special-ops forces just now being pondered in Washington, this latest Osprey hitch comes at an inopportune time. ®