with particulate matter or the fluid contains a substance
not readily removed by the internal filters. Flushing is a
decontamination method in which contaminated
system fluid is removed to the maximum extent
practicable and then discarded. It is a draining process
that is generally accomplished by powering the aircraft
system with a portable hydraulic power supply and
allowing the contaminated return line fluid from the
aircraft to flow overboard into a suitable receptacle for
disposal. In effect, filtered fluid from the portable
h y d r a u l i c p ow e r s u p p l y i s u s e d t o d i s p l a c e
contaminated fluid in the system and to replenish it
with clean serviceable fluid.
Purging is a decontamination process in which the
aircraft hydraulic system is drained to the maximum
extent practicable and the removed fluid discarded. A
suitable cleaning agent is then introduced into the
Figure 8-48.--Contamination analysis kit.
hydraulic system and circulated as effectively as
possible to dislodge or dissolve the contaminating
substances. The cleaning operation is followed by
complete removal of the cleaning agent and its
r e p l a c e m e n t w i t h n ew h y d r a u l i c f l u i d . U p o n
completion of purging, the affected system is subjected
determines that the contamination level in a piece of
to a period of flushing and recirculation cleaning to
support equipment exceeds the authorized limits, you
ensure adequate decontamination.
can decontaminate the unacceptable equipment by
Purging of the support equipment hydraulic
system is performed only upon recommendation from,
and under the direct supervision of, the cognizant
engineering activity. It is the responsibility of the
Recirculation cleaning is used when equipment is
cognizant engineering activity to select the required
found to be unacceptably contaminated with
cleaning agents, provide detailed cleaning procedures,
particulate matter (in excess of Navy standard class 5)
and perform tests upon completion of purging to
but the fluid is otherwise satisfactory. Recirculation
ensure satisfactory removal of all cleaning agents.
cleaning is a decontamination process in which the
When possible, a purging operation is done at a Naval
system to be cleaned is powered from a clean external
Air Rework Facility. Intermediate maintenance
power source and cycled so as to produce a maximum
activities are not authorized to perform system purging
interchange of fluid between the powered system and
without direct depot supervision.
t h e s u p p o r t e q u i p m e n t u s e d t o p ow e r i t .
As with the hydraulic fluid sampling procedures,
Decontamination is accomplished by circulating the
contaminated fluid through the hydraulic filters in the
purging are contained in chapter 7 of the Aviation
aircraft system and in portable hydraulic power
s u p p l i e s . Wi t h t h i s m e t h o d , t h e e q u i p m e n t i s
self-cleaned by using its internal filters--the 3-micron
elements in particular.
the following particles?
The flushing method of decontamination is used
when the support equipment is heavily contaminated