and maintenance manual for the particular
equipment or as directed by the MRCs.
1. All samples should be taken from circu-
lating systems, or immediately upon shutdown,
while the hydraulic fluid is within 5°C (9°F) of
normal system operating temperature. Systems
not up to temperature may provide nonrepre-
sentative samples of system dirt and water
content, and such samples should either be
avoided or so indicated on the analysis report. The
first oil coming from the sampling point should
be discarded, since it can be very dirty and does
not represent the system. As a general rule, a
volume of oil equivalent to one to two times the
volume of oil contained in the sampling line and
valve should be drained before the sample is
taken.
2. Ideally, the sample should be taken from
a valve installed specifically for sampling. When
sampling valves are not installed, the taking of
samples from locations where sediment or water
can collect, such as dead ends of piping, tank
drains, and low points of large pipes and filter
bowls, should be avoided if possible. If samples
are taken from pipe drains, sufficient fluid should
be drained before the sample is taken to ensure
that the sample actually represents the system.
Samples are not to be taken from the tops of
reservoirs or other locations where the contami-
nation levels are normally low.
3. Unless otherwise specified, a minimum of
one sample should be taken for each system
located wholly within one compartment. For
ship’s systems extending into two or more
compartments, a second sample is required. An
exception to this requirement is submarine
external hydraulic systems, which require only one
sample. Original sample points should be labeled
and the same sample points used for successive
sampling. If possible, the following sampling
locations should be selected:
a. A location that provides a sample
representative of fluid being supplied
to system components
b. A return line as close to the supply tank
as practical but upstream of any return
line filter
c. For systems requiring a second sample,
a location as far from the pump as
practical
Operation of the sampling point should not
introduce any significant amount of external
contaminants into the collected fluid. Additional
information on hydraulic fluid sampling can be
found in NAVAIR 01-1A-17.
Most fluid samples are submitted to shore
laboratories for analysis. NAVAIR 17-15-50-1
and NSTM, chapter 556, contain details on
collecting, labeling, and shipping samples.
NAVAIR 01-1A-17 contains procedures for
unit level, both aboard ship and ashore, testing
of aviation hydraulic fluids for water, particulate,
and chlorinated solvent contamination.
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