accomplished at all levels of maintenance through the
use of Contamination Analysis Kit 57L414.
Hydraulic system fluid sampling is accomplished on a
periodic basis according to the applicable
maintenance instruction manual (MIM), maintenance
requirement cards (MRC), and rework specification.
Figure 4-1 shows the requirements for periodic fluid
surveillance.
You should perform analysis of hydraulic systems
if extensive maintenance and/or crash/battle damage
occurs.
You should perform the analysis when a
metal-generating component fails, an erratic flight
control function or a hydraulic pressure drop is noted,
or there are repeated and/or extensive system
malfunctions. Analysis is performed when there is a
loss of system fluid, or when the system is subjected
to excessive temperature. Analysis is also performed
when an aircraft is removed from storage in
accordance with NAVAIR 15-05-500. You should
perform analysis of the hydraulic system anytime
hydraulic contamination is suspected.
MAINTENANCE PROCEDURES
The general contamination control procedures
hydraulic systems, subsytems,
components, and fluids are requirements for each
maintenance level.
Hydraulic fluid contamination
controls ensure the cleanliness and purity of fluid in
the hydraulic system. Fluid sampling and analysis is
performed periodically. Checks are made sufficiently
before the scheduled aircraft induction date so that if
fluid decontamination is required, it may be
accomplished at that time. The condition of the fluid
depends, to a large degree, on the condition of the
components in the system. If a system requires
frequent component replacement and servicing, the
condition of the fluid deteriorates proportionately.
Replacement of aircraft hydraulic system filter
elements takes place on a scheduled or conditional
basis, depending upon the requirements of the
specific system. A differential pressure flow check
and bubble point test are performed to properly
evaluate the condition of a cleanable filter element.
These two checks are done to verify that the element
is good before it is installed in a system or component.
Many filter elements look identical, but all of them
are not compatible with flow requirements of the
system.
If the hydraulic system fluid is lost to the point
that the hydraulic pumps run dry or cavitate, you
Figure 4-1.—Periodic fluid surveillance requirements.
4-2
and testing of
