TM 1-1500-204-23-11
or Corrosion Resistant
a collar. Advantages of Hi-Lok fasteners include
Steel (CRES). Do not
their light weight, high fatigue resistance and high
use cadmium-plated or
strength. Another advantage for using Hi-Loks is
aluminum fasteners.
the fastener cannot be over torqued. The collar has
3.
Install fasteners wet with
a regulated break off groove which shears off at a
MIL-PRF-81733 sealant.
predetermined torque, leaving the lower portion of the
4.
Ensure the proper torque
collar seated with the proper torque without additional
is used on all fasteners
torque inspections.
or bolts.
5.
Use 100 or 130
(2) Blind Fasteners. Blind fasten-
countersink tension
ers are designed for applications where only one
head fasteners when
side of the repair area is accessible. These fasten-
the countersink is in
ers are secured in place by a collar that deforms
the carbon/epoxy lam-
and bears up against the backside material. If the
inate.
The head of
backside material is composite, a Composi-Lok or
a tension fastener is
Composi-Lok II must be used. The Composi-Lok
20-40% larger than the
fasteners have a larger upset surface or footprint
head of the same diam-
when installed. This larger bearing area helps pre-
eter shear fastener.
vent localized delamination around a fastener hole and
The larger head helps
increases the resistance to "tipping." Figure 3-8 shows
prevent fastener pull
some basic design differences between the Visu-Lok
through and provides a
(Jo-Bolt) and Composi-Lok fastener. Part numbers
larger bearing surface.
and other descriptive information are listed in table
The 130 is used for
3-3 for both conventional blind fasteners and Com-
very thin laminate appli-
posi-Lok blind fasteners. These are for illustrative
cations.
purposes only. Consult the system speciic technical
6.
Exercise
caution
to
manual for proper fastener selection.
insure the proper coun-
tersink is used for the
(a) Visu-Lok. This blind fas-
different countersink fas-
tener, commonly called a Jo-Bolt, is for installation
tener angles.
where the backside material is metal. The fastener
consists of a preassembled nut, threaded bolt and
(3) Patch and Fastener Installa-
sleeve.
tion. Once fastener holes in the metal or composite
repair plate and the composite skin are drilled (or
(b) Visu-Lok II. The Visu-Lok
reamed) to full size, the plate can be installed on
II is similar to the Visu-Lok except a drive nut
the skin with mechanical fasteners. See Chapter 6-8
is located on the stem of the fastener. This feature
for drilling instructions. A variety of fastener types
reduces logistical elements since only two nose pieces
may be used to affect the repair. Different installation
are required to install all diameters and head styles.
and inspection procedures are required for the differ-
ent type of fasteners. This section briely describes
(c) Composi-Lok. Composi-
the different fasteners commonly used in a bolted
Loks are speciically designed for fastening car-
composite repair and the installation and inspection
bon/epoxy composite joints with one side access. The
requirements for each type fastener. Also listed are
Composi-Lok is similar in design to the Visu-Lok.
some general guidelines and practices that can be
However, once installed, the sleeve upset is larger,
applied to composite bolted repairs. Refer to TM
distributing the bearing loads over a larger area.
1-1500-204-23-10 Chapter 7 for more information on
these and other fasteners.
(d) Composi-Lok II.
The
Composi-Lok II is similar to the Composi-Lok except
b Fastener Types. There are many
a drive nut is located on the stem of the fastener. As
factors to consider when selecting fasteners for a par-
with the Visu-Lok II fastener, the drive nut reduces
ticular application. These factors must be addressed
installation time and reduces the tooling required.
for all of the materials the fastener penetrates. They
With two nose adaptors, all diameters and head
include: strength (lap/shear/tension/bearing), corrosion
styles can be installed.
potential, permanence, and accessibility.
(1) Hi-Lok Fasteners. Hi-Loks
are two piece fasteners using a threaded pin and
3-15
