substitute part must have the same mag-
the instruct ions; some parts can't be reused. Then,
netic properties and characteristics as the one
and only then, may you use the removed parts.
prescribed.
The hardware you should use when installing
electrical equipment in aircraft is specified in the
Style. Most items of mounting hardware are
applicable MIM. You should always use proper
avawe in various styles. It is usually easy to find
parts. If you need to substitute, make sure the
screws and bolts that are the same in all respects
substitute item is satisfactory.
except the type head. Use these parts as sub-
General information about mounting parts
stitutes, provided they have all required special
and consumable components can be found in
various Navy training manuals. Aircraft Structural
features.
Hardware for Aircraft Repair, NAVAIR 01-1A-8,
and Installation Practices Aircraft Electric and
Special features. If a bolt requires torque to
Electronic Wiring, NAVAIR 01-1A-505, are
a given value, a suitable torque wrench for that
type part must be available. If the MIM calls for
sources of detailed information.
lockwire, the part must have suitable provisions.
If you can't get the mounting parts specified
by the applicable illustrated parts breakdown
(IPB), you may make a temporary installation
Lubrication or coating. If specific instructions
call for lubrication or coating of the parts, follow
using suitable substitute parts. Replace these parts
with the proper items as soon as you receive them.
those instructions for the substitute part as well
as for the prescribed part.
Always check with the work center supervisor
before you make any substitution. When making
SHOCK MOUNTS
part substitutions, you should give special con-
sideration to the following factors:
Electrical and electronic equipment must be
Corrosion. Pay attention to the chemical or
protected from the effects of vibration in aircraft,
metallic composition of the part. Choose a part
as vibration is a major problem. Most amplifiers,
instrument panels, and other fragile parts have
that doesn't contribute appreciably to the danger
of corrosion.
shock mounting protection. Shock mounts are
also known as vibration insulators. You can trace
the failure of many systems to faulty shock
Strength. The strength of the substitute part
must be the same, or greater than the one
mounts; therefore, you should periodically check
prescribed. (When determining the strength,
shock mounts. If you find that they are defective,
replace them before equipment is damaged.
consider the tensile, compression, and shear
Figure 2-15, views A and B, shows two types
strength, as applicable to the specific use.)
of shock mounts used in naval aircraft. View A
Size. Substitute nuts, bolts, and screws should
shows mounts that are individually replaceable.
be the same size as the prescribed item. In all
Each mount has a rod that extends into the
vibration eliminating material. You can replace
cases, washers must have the same inner diameter
this type of mount by drilling out the mounting
as the prescribed item. A different outer diameter
base rivets and riveting the replacement in
or thickness is acceptable.
position. The replacement must be of the same
Length. The length of substitute screws or
size and type as the mount that it is replacing. The
weight of the unit being protected determines the
bolts must be enough for the particular installa-
type of mount you use. If you use a mount
tion. However, length can't be long enough to in-
designed for a heavier unit, it won't give to protect
terfere with any moving part. Hardware shouldn't
the unit. [f you use a mount designed for a lighter
come in contact with other aircraft items, such
unit, it can easily pull away from the base and
as electrical wiring, hydraulic lines, etc.
damage the unit.
The shock mount unit in figure 2-15, view B,
Magnetic properties. Equipment installed in
is used with a particular piece of equipment. You
specific areas of the aircraft shouldn't cause
replace this type of mount as a unit. The vibration
distortion of the magnetic fields of the area.
insulators are made of hollow rubber and locked
Examples of such items include the magnetic
into place when manufactured. Inspect these
compass, magnetic anomaly detection equipment,
insulators for cracks or splits. If you find damage,
radio direction finder, or gyros. In areas
replace the complete shock mount unit.
containing these types of equipment, any
