The components of the contamination analysis kit
are shown in figure 4-4. Look at this figure as you
read about the procedure you should follow to prepare
hydraulic fluid for contamination analysis.
The Millex point-of-use filter unit consists of two
threaded half-sections and an internal support screen.
Use forceps to place one 25-mm solvent filter on the
gridded plastic surface of the filter holder.
NOTE: Packaged filter membranes are
separated by blue separator discs. Remove
separators before installing solvent filter in
the filter holder.
Position the perforated support screen on top of
the solvent filter to provide support for both sides of
the solvent filter. Reassemble the two halves of the
filter holder fingertight
Fill the wash bottle (with
short spout) with an approved solvent. Trichloro-
trifluoroethane Solvent MIL-C-81302A, Type II
(Freon), is the preferred solvent because it evaporates
rapidly and is compatible with materials used in the
analysis kit. MIL-T-81533 (1,1,1-trichloroethane
solvent) is an alternative solvent. However, when
using this sol vent, sufficient drying time must be
allowed. Dry-cleaning solvent, P-D-680, is also a
suitable substitute. As with the 1,1,1 trichloroethane
solvent, sufficient drying time must be allowed.
MIL-C-81302 evaporates rapidly and will
Use only in a well-
ventilated area. MIL-C-81302 should not be
used in large volumes, and all containers
must be closed when not in use. A standby
safety observer must be present during test
to ensure the person performing the test is
not overcome by fumes. Failure to observe
proper safety precautions could result in
personal injury or death to personnel.
When MI L-C-81302 is not available,
MIL-T-81533 or P-D-680 may be used only
when an immediate demand exists.
However, if either solvent is used,
appropriate precautions must be observed
due to their toxicity and flammability. In the
event that either MIL-T-81533 or P-D-680
must be used, use only in a well-ventilated
area and avoid inhalation of vapor. P-D-680
is flammable. Keep it away from open
flame. Failure to observe proper safety
precautions could result in personal injury
or death to personnel.
Fill the wash bottle (with long spout) with
dry-cleaning solvent P-D-680 to flush sampling
points. Replace their screw caps. Attach the filter
holder to the wash bottle with the short spout. Make
sure the tip of the wash bottle is not damaged by
forcing the filter holder on too tightly. If damaged,
the other wash bottle may be modified by carefully
cutting off the tip so that the filter holder will fit. The
damaged wash bottle may then be used for flushing
fittings and sampling points.
Clean the required number of sample bottles
before use by rinsing and flushing them with filtered
solvent. Fill the bottle to be cleaned approximately
half full. Replace the cap on the opening, shake the
sample bottle several times, remove the cap, and
dump the contents.
Repeat this operation three or
more times to remove residual hydraulic fluid. When
the bottle is considered clean, flush down the external
threads of the sample bottle and the internal threads of
the bottle cap with filtered solvent. Replace the cap
on the bottle.
Samples taken from aircraft hydraulic systems
and SE should be representative of the fluid in the
system under test. Aircraft samples should be taken
immediately after flight. If postflight samples cannot
be obtained, the system is cycled according to
directions in the applicable aircraft MIM or MRC
before drawing a sample. Before sampling SE
hydraulic systems, recirculate the fluid for a
minimum of 5 minutes at full flow rate or for a
proportionately longer time at a lower flow rate.
Remove external contaminants from the sampling
point by flushing it with solvent and wiping the
sampling point with clean, disposable wiping cloths.
When the sampling point is visibly free of
external contaminants, subject it to a final solvent
flush. Sampling points not adequately cleaned before
use may produce test results that needlessly cause the
rejection of the system under test. Begin the flow of
fluid to be sampled, by appropriate means, allowing
an initial quantity to flow into a waste receptacle.
This procedure serves to flush away any contaminant
in the sampling line and any contaminants generated
by mechanical operation. Without interrupting the