midway on the insert. This produces a gripping effect
may be drilled or undrilled on the nut end. Coarse
on the engaging screw. For quick identification, the
(NAS183) and fine (NAS184) thread studs are
self-locking, mid-grip inserts are dyed red.
manufactured from alloy steel and are heat-treated.
They have identical threads on both ends. The stepped
Q3-7.
What fastener has a shear and tensile
stud has a different thread on each end of the stud. The
strength at least equal to the requirements of
lockring stud may be substituted for undersize or
AN and NAS bolts?
oversize studs. The lockring on this stud prevents it
Q3-8.
A 4002 series Camloc fastener consists of
from backing out due to vibration, stress, or
what total number of principal parts?
temperature variations. Refer to the Structural
Hardware Manual, NAVAIR 01-1A-8, for more
Q3-9.
What metal is used in the construction of
detailed information on studs.
threaded pins of Hi-lok fasteners?
HELI-COIL INSERTS.--Heli-coil thread inserts
Q3-10.
Jo-bolts are available in what three head
are primarily designed to be used in materials that are
styles?
not suitable for threading because of their softness. The
Q3-11.
How many threads must be extending through
inserts are made of a diamond cross-sectioned stainless
the nut of a replacement bolt for it to be
steel wire that is helically coiled and, in its finished
considered the correct length?
form, is similar to a small, fully compressed spring.
There are two types of heli-coil inserts. See figure 3-31.
Q3-12.
What type of wrench is used to loosen
One is the plain insert, made with a tang that forms a
or
tighten
countersunk-head
and
portion of the bottom coil offset, and is used to drive the
internal-wrenching bolts?
insert. This tang is left on the insert after installation,
Q3-13.
How many times can a self-locking nut be
except when its removal is necessary to provide
reused?
clearance for the end of the bolt. The tang is notched to
break off from the body of the insert, thereby providing
Q3-14.
What type of nut is designed to be used with a
full penetration for the fastener.
cotter pin or safety wire?
The second type of insert used is the self-locking,
Q3-15.
What type of nut is used on an assembly that is
mid-grip insert, which has a specially formed grip coil
frequently removed?
Q3-16.
What type of nut is used to ensure a
permanent and vibration proof connection?
Q3-17.
What three types of screws are most
commonly used in aircraft construction?
Q3-18.
What type of screw is as strong as a bolt of the
same size?
Q3-19.
Flush-head machine screws are available in
what degree(s) of head angle?
Q3-20.
What type of screw should NOT be used when
replacing an original screw in an aircraft
structure?
Q3-21.
When should a ball socket and seat washer be
used on a bolt?
Q3-22.
When you install a hose between two duct
sections, what is the maximum allowable gap
between the duct ends?
Q3-23.
If the correct torque value is not specified on a
Marman clamp, what manual should you
consult to locate the correct torque value?
Figure 3-31.--Heli-coil insert.
3-18
