PS Magazine - TB 43-PS-724

PS, The Preventative Maintenance Monthly

ISSUE 724

MARCH 2013
PS Magazine - TB 43-PS-724 - Page 13 of 33
23
PS 724
MAR 13
Dear SFC Blade,
Your article on Pages 22-23 of PS 718 (Sep 12) is not quite correct
on how the stabilators move.
You imply that applying hydraulic pressure to the aircraft could make the
stabilators move. Actually, the stabilators on both the Black Hawk and
Apache are electrically-driven systems. They move when external electrical
power is applied from the AGPU.
What moves when AGPU hydraulic pressure is applied to aircraft are the
flight controls and the AH-64 pylons.
Mr. Graden Pitt
Ft Hood, TX
Dear Mr. Pitt,
Thanks for writing and letting us know about the mistake. It’s readers like you
that keep us on our toes, so we appreciate your keen eye. We and the headshed
missed this one.
You are correct about the stabilators being electrically-driven systems. We don’t
want any confusion about what systems can move and how.
In fact, the artwork shows the AGPU hooked to the aircraft for applying
external hydraulics. Based on the artwork, the stabilator could not move because
there is no electrical power being applied. The old artwork should’ve shown the
AGPU hooked to the hyrdaulic lines, and not the aircraft.
To brieFy restate what the article
should
have said concerning the AGPU and
aircraft: Electrical power from the AGPU can move systems like the stabilator
and other electrically-driven systems. And applying AGPU external hydraulics to
aircraft can move Fight controls and change the pitch angle of blades and other
hydraulic components.
Remember, when a block is installed, you must have a Remove Before Flight
streamer, NSN 8345-00-673-9992, attached. It must be
visible
on the outside of the
surface of the aircraft so other mechanics will know maintenance is taking place.
Always use the blocks the right way. That means you must install them for each
rotor head job where the TM or IETM procedure calls for their use. Use the block for
maintenance on ±ight controls, too. They must remain installed until the job is done.
It also means you’ll have to adjust the equipment so that the blocks can be removed
when the task is complete.
When you install a block, it must be placed on the piston with the slot of the
block facing outward and the latch up. Just dropping the locking latch in place isn’t
enough—you must tighten the screw to hold the latch down.
UH-60/AH-64/CH-47 Series…
A
pplying
E
xternal
H
ydraulics to
A
ircraft
CH-47D/F…
Use
Blocks
For
Maintenance
Install block with slot outward and latch
up so weight of actuator rests on block
mechanics, when you
are doing any type
of maintenance on
chinook rotor heads
or flight controls,
be safe around the
hydraulics.
you
need
safety and
stability, so
don’t
block out the need
for the servocylinder
safety blocks, nsn
1
7
30-01-264-6254.
the
actuators
sit on the
blocks,
taking the
weight off
the flight
controls
so you can
perform
maintenance.
whatcha
got there,
smitty?
I’m watching sergeant
blade explaining some-
thing by video.
we’re making
a change to
something we
said last year.
724 22-23.indd
1-2
1/29/13
2:54 PM
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