Rubber Hose. Evidence of deterioration of rubber hose assemblies
is urgent cause for hose replacement. Examples of such deterioration
are separation of rubber covers or braid from the liner, cracks,
hardening, and lack of flexibility.
Other types of damage that are cause for replacement of rubber
hose are--
Cold flow -- a deep permanent impression or crack produced by
pressure of the hose clamp.
Weather check -- weather damage that is deep or wide enough to
expose the fabric.
Broken wires -- two or more broken wires per plait, six or more
broken wires per linear foot, or any broken wire in a position
where kinking is suspected.
(For pressures of 500 psi and
over)
Teflon Hose. Installed teflon hose assemblies must be inspected
for evidence of deterioration due to wire fatigue or chafing at the
periods
prescribed
in
the
applicable
aircraft
inspection
or
maintenance manuals.
Replacement of these lines must be made when
any of the following conditions are found:
Leaking -- static leaks exceeding one drop per hour.
Excessive wire damage -- two or more broken wires in a single
plait, more than six wires pre linear foot, or any broken wire
in a position where kinking is suspected.
Distortion -- any evidence of abrasion, kinking, bulging, or
sharp bending.
FABRICATION OF HOSE ASSEMBLIES
Hose assemblies, for the most part, are available through supply
channels as factory prefabricated parts.
For field expediency or
when the required assemblies are not available they can be field
fabricated in accordance with the following specifications and
procedures.
Fabricating Medium-Pressure Rubber Hose Assemblies.
Medium-
pressure rubber hose assemblies are fabricated from bulk hose
conforming
to
military
specification
MIL-H-8794
and
fittings
conforming to military standard MS 28740.
Prior to the assembly
process and before cutting, visually check the bulk hose for any
mutilations, marks, seams, and excessive graphite.
Check the
fittings for mutilations to the threaded areas, nicks,
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AL0907
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