periodic aircraft rework, and maintenance performed
as a result of actual or suspected malfunctions.
Identify the types of
hydraulic fluid used in naval aircraft and
Aircraft hydraulic systems are capable of reliable
unattended operation for long periods of time, but
some periodic service is generally required. Such
service will either be fluid servicing or air bleeding.
Hydraulic fluids MIL-H-5606, MIL-H-83282, and
MIL-H-81019 are used in automatic pilots, shock
absorbers, brakes, control mechanisms, servo control
systems, and other hydraulic systems using seal
materials compatible with petroleum-based fluids.
The primary use for hydraulic fluid MIL-H-46170 is
as a preservative fluid for hydraulic systems and
MIL-H-5606 was the principal hydraulic fluid
used in naval aircraft before MIL-H-83282 was
MIL-H-5606 consists of petroleum
products with additive materials to improve viscosity
(temperature characteristics), inhibit oxidation, and
act as an antiwear agent. The oxidation inhibiter was
included to reduce the amount of oxidation that
occurs in petroleum-based fluids when they are
subjected to high pressure and high temperature, and
to minimize corrosion of metal parts due to oxidation
and resulting acids.
The temperature range of
MIL-H-5606 is between 65°F to +275°F. It is dyed
red so it can be distinguished from incompatible
fluids. Hydraulic fluid MIL-H-5606 is compatible
with hydraulic fluid MIL-H-46170.
MIL-H-83282 is the principal hydraulic fluid
used in military aircraft. MIL-H-83282 replaces
MIL-H-5606. It is dyed red so it can be distinguished
from incompatible fluids. MIL-H-83282 has a
synthetic hydrocarbon base and contains additives to
provide the required viscosity and antiwear
characteristics, which inhibit oxidation and corrosion.
It is used in hydraulic systems having a temperature
range of40°F to +275°T. Flash point, fire point, and
spontaneous ignition temperature of MIL-H-83282,
which is fire resistant, exceeds that of MIL-H-5606
by more than 200°F. The fluid extinguishes itself
when the external source of flame or heat is removed.
Hydraulic fluid MIL-H-83282 is compatible with all
materials used in systems presently using
MIL-H-5606. It maybe combined with MIL-H-5606
with no adverse effect other than a reduction of its
fire-resistant properties. MIL-H-83282 is now
required in the main systems of all fleet aircraft
previously using MIL-H-5606. MIL-H-83282 is not
used in some viscous dampers due to its
MIL-H-81019 is an ultra-low temperature
hydraulic fluid. It is used in aircraft when extremely
low surrounding temperatures are expected.
MIL-H-81019 consists of petroleum products with
additive materials to improve its viscosity
(temperature characteristics), increase its resistance to
oxidation, inhibit corrosion, and act as an antiwear
agent. It is dyed red so it can be distinguished from
other incompatible hydraulic fluids. In extreme
emergencies, it is interchangeable with hydraulic
MIL - H - 5606 and
MIL-H-81019 is designed to operate in hydraulic
systems having a temperature range between 90°F to
The primary use of MIL-H-46170 is as a
preservative fluid for hydraulic systems and
components storage. Components serviced with this
preservation fluid should be drip drained and filled
with MIL-H-83282 prior to being installed. This fluid
should not be mixed under any other condition. It is
also used as a testing medium in stationary test stands
that have a temperature range between 40ºF to
+275°F. It is dyed red so it can be distinguished from
When mixing or combining
hydraulic fluids, the aircraft logbook or S/E
logs and records need to be annotated when
this is done.
FLUID SERVICING AND SUPPORT
Identify the support
equipment used to service and test aircraft
hydraulic systems and components.
Fluid servicing consists of adding new filtered
hydraulic fluid to a system, which replaces fluid lost
through leakage, system maintenance, or malfunction.
The type of support equipment varies, depending on
the type of aircraft youre working on. As an AM,
you must know this equipment and know how to