Osprey’s Grounded

[KevinB]

US military grounds entire fleet of Osprey aircraft

The announcement comes one week after eight Air Force Special Operations Command service members died in an Osprey crash off the coast of Japan.

www.militarytimes.com

Gee so glad FLRAA is a tilt rotor…

 

[calculus]

Substantially different architecture, but yes, I share your concern...

Looks like this may have been an engine fire, based on witness reports: All V-22s Grounded, Probe Finds Materiel Failure Possible In USAF Crash | Aviation Week Network

 

[KevinB]

Substantially different architecture, but yes, I share your concern...

Arguable, as the only significant difference is the engines don’t rotate, the gearbox linkage for the rotor is very similar.

Looks like this may have been an engine fire, based on witness reports: All V-22s Grounded, Probe Finds Materiel Failure Possible In USAF Crash | Aviation Week Network

I really like the idea of the tilt rotor - as speed is life in a lot of situations. But I don’t think the design is nearly as solid as fixed rotary wing.

 

[KevinB]

More on the Osprey issues.

Ospreys had history of safety issues long before they were grounded

The clutch aspect is also suspect on the Bell V-280 Valor as while unlike the Osprey the engines don’t rotate, the rotors are required to turn at the same speed, the clutch and gear box are are a tad bit more complicated due to the rotation of the rotors and housing, while the engine is stationary on the fuselage.

Now one thing that jumped out at me, @Good2Golf can answer, are the Hook rotors synched like that?
(Albeit since the engines and rotor housing is non rotational, I suspect that make any linkage a little easier and more robust).

 

[Good2Golf]

@KevinB, Hooks definitely have a synch shaft system running fore-aft passing up to ~5,000shp in each direction from the combiner gearbox and from each engine (total of 9 shaft segments), but like you noted, its geometry is essentially fixed by the structure of the airframe and static positions of the transmissions and engines. The major issue in the past (mostly A and B models, was a feature that had basically a dog-clutch just ahead of the CBOX that had a manual lever to disconnect the fwd and aft shafts so that the rotor heads could be moved independently during maintenance. There were some ‘issues’ where that de-synch level popped out of position in flight which was a bad thing, and also a few limited cases where a synch shaft thrust bearing was installed backwards and the rotors skipped a tooth or two (but the crew got that one back on the ground).

Ironically, I had no issue flapping around in that, even with something like 15’ of ‘eggbeater overlap’ but watching massive parts like engines/nacelles pivoting (and then the whole rotor system pivot 90°) on a V-22….

Maybe these will be better?