TM 10-5410-223-14/1
hours. Length of time decreases with increased
(c) Superficial stretch marks which may
temperature. Discard time should be at the point
appear on the rivet are not detrimental to rivet
where the epoxy is no longer pliable enough to be
strength and are acceptable.
worked into the cavity.
(d) After stem trimming, stem can be
(4) Application of potting compound. Apply
checked for tightness by applying a force of ap-
the adhesive compound observing the following:
proximately ten pounds (4.5 kg) to the trimmed stem
(a) Using a clean tongue depressor, trowel
of the rivet, push steadily; do not strike. If the stem
the adhesive compound into the insert hole,
is neither pushed out or loose, tightness is
(b) Exercise care during the troweling
satisfactory.
operation to prevent trapping air pockets in the
(e) Rivet head gapping shall be checked with
insert hole,
a 0.002 (0.0051 cm) feeler gage. Rivets with a 0.002
(c) Use enough adhesive to ensure that the
(0,0051 cm) gap on more than 40 percent of the rivet
hole is completely full after the insert is put in.
head circumference shall not be acceptable,
(5) Installation of inserts, Use the same size
(f) A partial gap on a round surface is ac-
and type of insert as the one removed, observing the
ceptable, provided the rivet head bears at tangent
following:
points, as shown in figure 4-16.
b. Insert Replacement,
NOTE
The washer indicated in step (a ) below must seat
(1) Removal of defective inserts,
firmly on the upper flange of the insert to assure
NOTE
proper positioning of the insert during set-up period.
Bolt and/or capscrew size used in the pulling of
inserts and size of hole drilled in pulling bar will vary
(a) Turn screw and washer completely and
for the particular insert being removed,
tighten into insert.
(b) Clean outside of insert with a lint-free
Some loose inserts may be removed by screwing a
cloth soaked with methly-ethyl-ketone. Allow insert
capscrew into the opening and pulling the insert out
to dry.
with a pliers; if this method fails, proceed as follows:
Drill a hole about 3 inches (7.62 cm) from the end of a
(c) Place insert in hole and press down firmly,
(d) Remove adhesive residue left on the
1 inch (2.54 cm) x inch (0.635 cm) x 12 inch (30.48
surface by wiping hole area with lint-free cloth
cm) steel bar, Place the hole of the bar over the insert
soaked with methly-ethyl-ketone.
and thread a capscrew through the bar and into the
(e) Cover the hole area with tape, making
insert. The capscrew should be long enough to
sure that the washer is held down firmly by the tape.
"bottom" in the insert and leave clearance between
A diagram of a typical installation of an insert in a
the head of the screw and the bar, Turn the cap-
honeycomb panel is given in figure 4-15,
screws with a pneumatic wrench and pry outward
(f) Nonstructural inserts should be allowed to
with the metal bar until the insert is pulled out,
(2) Preparation, To pot an insert successfully,
cure for at least 4 hours prior to handling or usage.
Inserts on which them is structural dependency
all of the old epoxy must be removed from the
should not be disturbed for 72 hours. Epoxy
facings and honeycomb, The epoxy can be broken up
manufacturer's specification sheets list the following
with a small chisel and hammer. A rotary file and
cure times to attain maximum strength:
drill motor will also be effective, Remove loose
77F.(25C.)
72 - 120 hours
particles from the hole using clean compressed air, a
150F.(66C.) 3 - 4 hours
screwdriver or a needle-nose pliers, Scrape all of the
200F.(98C.)
40 - 60 hours
old potting compound off the plate and container,
Install the inserts and hand tighten with capscrews
c. Repair Procedure For Honeycomb Paneling
using flatwasher between each insert and container,
Using Plug Patches and Adhesive,
Clean the inserts with methyl-ethyl-ketone and allow
(1) Mixing of two part adhesive. Mixing of
the inserts to dry.
adhesive used for repair of honeycomb core shall be
NOTE
accomplished as follows:
Do not touch the inserts after they have been
(a) Use a mixing ratio of 50 parts accelerator
cleaned.
to 50 parts base by volume.
(3) Potting resin (adhesive) mixing, The
WARNING
adhesive compound shall be blended using a 50%
main and 5070 curing agent ratio. Blend the resin
Adhesives and solvents are highly flam-
and the curing agent together in a paper mixing cup
mable; perform work in well-ventilated area
using long, smooth strokes, rather than a whipping
and away from fire.
motion. Pot life at normal ambient temperature (75
(b) Add the proper amount of adhesive base
5F.) (24C, 15C.) is approximately 2
4-61
