Prepare the assembly as previously described. Cut
When the void areas are large, it is necessary to
out the damaged skin facing with a hole saw or aviation
remove the facing over the damaged area and follow the
snips. File the edges of the hole smoothly. Using a
repair procedures for a puncture. See figure 5-16.
pocketknife, carefully cut out the damaged core.
Repairing Punctures
A puncture is defined as a crack, break, or hole
CAUTION
through one or both skin facings with resulting damage
Do not damage the opposite facing. Install a new
to the honeycomb and/or balsa wood core. The size of
core filler and complete the repair as described in
the puncture, amount of damage to the core, assembly
view A of figure 5-16.
to be repaired (rudder, elevator, etc.), and previous
repairs to the damaged assembly are factors to be
considered in determining the type of repair to be made.
The repair shown in figure 5-16, view C, is used
Damage to a honeycomb and/or balsa wood core
when both skin facings and the core have been
assembly that exceeds a specified length or diameter in
damaged. To make this repair, use the same procedures
inches or the total number of repairs exceeds a specified
as described for views A and B of figure 5-16.
percentage of the total bonded area necessitates
BALSA WOOD CORE.--The repair shown in
replacement of the assembly.
figure 5-17 is used when no gain in structural strength is
NOTE: These figures are found in the applicable
structural repair manual.
HONEYCOMB CORE.--The repair shown in
figure 5-16, view A, is used when a puncture through
one skin facing has caused only minor damage to the
core material. To repair this type of damage, proceed as
follows:
Cover the component with a suitable protective
covering (polyvinyl sheet or Kraft paper). Cut out a
section of the protective covering that will extend
approximately 2 inches beyond the damaged area. Use
masking tape to hold the cutout in place. Stop-drill as
necessary through the skin facing only.
Strip the paint and protective coating 1 1/2 inches
beyond the stop drilled holes. Then, clean the stripped
area with a special cleaning paste. Fill the void with the
specified filler material to within approximately 0.063
inch of the skin facing, and cure as directed.
Prepare a round or oval patch large enough to
overlap the damaged area at least 1 inch. Apply sealant
to the undersurface of the patch and to the filler and skin
surface. Install the repair patch, maintaining correct
overlap, and clamp to the assembly to assure contact
with the skin facing. Cure as directed. Remove the
excess adhesive, and refinish as necessary.
The repair shown in figure 5-16, view B, is used
when a puncture through one skin facing has caused
extensive damage to the honeycomb core. When the
core has been damaged extensively, the damaged
Figure 5-17.--Balsa wood repair with filler plug and fabric
material must be replaced.
patch.
5-13
