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In the late
1980s, the military began experimenting with Combat Edge [CE]
systems. The Soviets were using a similar system starting in the
1960s. The CE system consists of an inflatable bladder in the
back & sides of the helmet. When the pilot pulls heavy G's,
the bladder inflates and forces the mask tighter against his face,
thereby keeping a good oxygen seal. The Air Force would take standard
55/Ps and convert [Tech Order] them to CE by using a separate
CE Kit. Tools you will need: Cordless drill; small phillips &
flat head screwdriver; 1/8 drill bit; 7/16 drill bit; needle nose
pliers; large philips head screw driver.
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You will also need
the Combat Edge conversion kit as shown to the right. The kit
includes: Helmet bladder; quick disconnect, female; quick disconnect
cover; 2 screws w/ lock washer; hose clamp; template; Hook &
Loop fasteners for the earcups (large pieces); Hook & Loop
fasteners for the TPL (small pieces). The kit also comes with
clear and dark MBU-20/P cut visors (not shown). The
quick disconnect kit is available for sale here.
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You will need
to remove the left male snap that the visor attaches to and the
left nape strap screw. These two piece will be replaced and will
hold the clear template in place. The earcup on the inside needs
to be pulled out as well. |
Shown here is
the clear template in place with the left male snap and the left
nape strap screw put back in the original places. There are holes
in the template (marked "A" & "B")- "A"
goes with the visor snap, "B" is where the nape screw
goes. This will place the template in the correct position on the
helmet for drilling. |
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Using the 1/8"
drill bit, drill holes at "C", "D", and
"F" as shown to the left. There are marks on the template
where exactly to drill. It is very important to be accurate in this
step because the screws will come through C & D to meet with
the female quick disconnect. |
Change to the
7/16" drill bit for this step. In the large oval area marked
"E", make 2 starter holes- each one equidistant from the
center and top/bottom. Start on one side and drill completely through.
Then do the next. This should get the area close to being done.
It may take a little clean up work with a file. After the holes
are drilled, trace the "E" area of the template. Then
it can be removed for the clean up work. |
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Here is the hole
after the template was removed and prior to the clean up work with
the edges. It looks a little rough, but the cover assembly will
hide any minor flaws. Be sure to replace the nape strap screw and
the male visor snap before going further. |
Dry fit the bladder
in the helmet and check for fitting and make sure the hole works
with the air filler tube (see below photo). You will also want to
check where the velcro (hook & loop) will need to be placed
on the bladder. |
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The angle on
the tube looks good here. You will want to make sure that it does
not get pinched in any area. We are about ready to put the female
quick disconnect on. One more thing before that though. |
The bladder is
shown with the hook part (stiff side) of the velcro attached. The
side of the bladder that is shown up will be facing the back of
the helmet. If you look inside the shell, there are 2 small pieces
of velcro attached- that is where the TPL is held in. You will have
corresponding pieces on each side of the bladder at the TPL attachment
points & at the earcup locations. Sounds confusing, but you
are basically putting the helmet bladder in-between the styrene
liner and TPL & the shell and earcups-- you need the velcro
on both sides of the bladder to reattach everything correctly. |
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OK, the bladder
is being held in with the velcro, now we can attach the metal female
quick disconnect [QD]. Make sure to insert the QD in the bladder
hose facing the correct way because it is tight and hard to spin
around. Use the hose clamp (a small zip-tie) to secure the fitting.
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Push the 2 screws
with lock washers through from the inside. The female QD is threaded
and will act as the nut. We are testing to make sure everything
is lined up here. Looks good. |
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Take the rubber
QD cover, at the end of it is a rubber string and a plug. Pull this
through hole "F" (the back hole). You may need a
small screw driver to help insert the plug. Next place the 2 holes
of the QD cover through the screws coming through the shell. The
metal QD will go over the top and hold down the assembly.
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This is the view
from the inside. You can see the yellow bladder, the bladder hose
going through the shell, the 2 screws with washers, and the nape
strap lock nut. Below you can see the finished QD assembly on the
outside of the shell. Note how the front of the QD cover is being
held down by the metal QD. |
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Back to the inside
now. Shown here you can see the Velcro pieces in the correct
position. Visualize on the other side of the bladder the corresponding
pieces in the same location holding the bladder in. These pieces
shown here will hold in the earcups & TPL. |
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Inside the back
of the helmet, these 2 pieces of "stiff side" velcro will
hold the TPL liner in place. |
Shown here, the
TPL has been replaced. All that is left to do now is replace the
earcups. |
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The MBU-20/P
CE mask is attached and the air feeder hose is plugged into the
metal QD on the helmet- perfect fit. The helmet is now an HGU-55/P
Combat Edge. |