PS Magazine - TB 43-PS-702
PS, The Preventative Maintenance Monthly
ISSUE 702
MAY 2011
36
PS 702
MAY 11
T
he Chinook is the Army’s work horse. If you don’t want it to pull up lame, make
sure both the aft landing gear swivel lock mechanisms are disengaged before towing.
When you remove all
electrical and hydraulic
power from the aircraft,
the swivel locks should
automatically
unlock,
but
in
some
cases
a
swivel lock may stay
engaged and the wheel
won’t be able to rotate.
If
the
lock
is
still
engaged when you tow
the aircraft, you could
rip out the swivel lock
mechanism
from
the
swivel housing.
Whenever you rely on electrical and hydraulic power for operation of any system,
things can go wrong. If you’ve had sticking problems with the locking mechanism,
the best thing to do frst is to troubleshoot the system like it says in TM 1-1520-240-
23&P or TM 1-1520-271-23&P.
Because the swivel lock system operates off
24 VDC, circuit breakers and a power steering
control box, electrical problem can originate
from any of these components or even a bad
wire.
Hydraulic power for swivel lock operation
is provided by the utility hydraulic system
thru the power steering/swivel lock module to
the swivel lock actuator. Any of these items can
go bad.
If you’ve been having problems with swivel
lock operation, it is a clear sign the swivel lock
piston rod has not been cleaned.
There is a scraper ring inside the swivel lock
actuator that keeps dirt and grime from entering
the actuator. IF hydraulic ±uid, dirt, grease
and grime accumulate on the piston rod and
scraper ring, they could gum up the works and
stick the lock in the down position (engaged)
when all power is removed from the aircraft.
Check the piston rods daily for cleanliness and
obstructions. Sometimes they gets overlooked
because they’re not easily accessible.
Towing Caution
CH-47D/F…
Towing Caution
Make sure lock mechanisms are
disengaged before towing
save yourself the
grief
of a grounded
helicopter.
clean the piston
rods and inspect the
swivel wheel locks
up
close to make sure
they are
not
engaged
before towing.
I thought
you
disengaged the aft
landing gear swivel
lock mechanism!
don’t let this
happen to you…or
your helicopter!
always make sure
you’ve disengaged
the swivel lock!
there’s
even more
info on the
swivel lock
system
belOw!
me?
I
thought
you
did
it!
702.36-37.indd
1-2
3/28/11
10:30 AM
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