Cause May Have Been Found, Already
One of the small fleet of V-22 Ospreys came back to Earth more
quickly than planned, earlier this week, at the Marine base at
Quantico (VA). It's undamaged, as far as we know; but mechanics and
technicians are swarming over the troubled bird, trying to figure
out exactly what went wrong with, reports say, 'the
hydraulics.'
'Hydraulics,' of course,
describes a huge load of systems in this plagued system. Since the
Osprey's inception roughly 20 years ago, 'hydraulics,' and control
systems therefor, have come up as trouble spots more than once.
The machine is inherently complicated; this is exacerbated by
the Osprey's need to have as many as three separate hydraulic
control systems. If it ever gets sorted out, and all the lines
aren't in the same places, the triple system should be plenty
safe.
The machine's main-drive tilt-rotor system, designed to take off
and land vertically, then pivot into position as as wing, is
hydraulically-operated; what would pass for 'normal' flight
controls, ditto; and power systems also move a lot of oil -- a
'hydraulic' problem could be nearly anything that isn't a
'computer' problem.
V-22 program spokesmen have told reporters that Monday's problem
was not related to hydraulic lines' chafing and defective
non-flexible titanium pipes, both of which have been fingered
before, as points of potential or actual failure.
No one was hurt in Monday's SNAFU; that news is gratefully
received. Two Ospreys killed 23 Marines in 2000, in two separate
accidents.
Bell's Official Statement:
On August 4, V-22 A/C #21 made an unscheduled landing during
a routine flight over the test range at the Marine Corps Base at
Quantico, Va. A backup system was automatically activated and the
aircraft completed a routine landing at the airfield at Quantico.
The V-22 performed as
designed with regard to pilot warning indications and the backup
system action.
A preliminary check revealed that a clamp holding a
hydraulic line filter was not installed as required with the
resultant vibrations causing the connection to loosen with loss of
fluid to the number two hydraulics system.
The faulty part was replaced and the clamp re-installed and
the aircraft then completed a normal flight back to its home base
at NAS Patuxent River, Md. This is not a design issue and the
missing clamp appears to be a maintenance or manufacturing issue
that is under review.