(c) Identify the nearest fastener holes out-
Apply a layer of cheesecloth on the
side the damaged region. Locate a
fastener location outside of the dam-
age region at each end of each fastener
(m) Apply an additional layer of the hydrocal
line to be transferred. These will be
mixture over the cheesecloth.
the index holes for the hydrocal blanket.
(n) Clean any putty mixture from around the
(d) Remove fasteners from the index holes.
(o) Allow the putty mixture to cure at room
(e) Clean repair area with a clean, dry wip-
temperature for one hour.
ing cloth saturated with solvent.
(p) Inspect the hydrocal mixture to ensure
Apply tape over any drain holes in the
the material has solidiied.
area to be drilled.
(q) Remove all fasteners from the bush-
(g) Apply petrolatum over an area approx-
imately 3 inches wide on each side of
the fastener rows. The petrolatum acts
Carefully remove the hydrocal drill blan-
as a release agent to keep the Hydrocal
kets from the surface.
from sticking to the part.
(s) Remove the damaged part.
(h) Install drill bushings into the fastener
and index holes. Ensure bushing size
corresponds with hole size.
Clean the damaged and surrounding
area as required.
Install fasteners through the drill bush-
ings as follows:
(u) Inspect the fastener holes in the mating
structure to insure the holes are within
For fastener holes requiring
threaded fasteners, install the
proper size bolt into the bushing.
(v) Position and temporarily secure the
Washers may be used under the
replacement part on the structure. Trim
bolt heads to get the correct grip
the new part as required.
length, if required. Engage the nuts
(w) Once part is trimmed to size and prop-
erly positioned, align the hydrocal drill
For fastener holes requiring perma-
blankets on the surface using the index
nent fasteners, install a temporary
sheet metal fastener through the
bushing and tighten.
(x) Insert fasteners through the index hole
bushings and tighten.
Mix hydrocal or other molding com-
pound and water using a 2:1 ratio to a
(y) Drill fastener holes in new part.
putty consistency. Mix an amount sufi-
cient to cover 2 inches on each side of
(z) Remove the fasteners from the drill
the bushings and be approximately 0.5
blanket and remove the drill blanket.
(k) Apply an initial layer of the hydrocal mix-
(aa) If the holes were transferred to metal
ture on the surface around the bush-
structure, remove the part and deburr