door is permitted and installed over the internal
structure, screws should be installed through the
cover plate into the internal structural member
wherever possible.
SKIN REPLACEMENT.—Sometimes damage
to the metal skin is so extensive that an entire panel
must be replaced.
Also, an excessive number of
patches or minor repairs to a section may require the
replacement of the entire panel.
As in all other forms of repairs, the first step is to
inspect the damaged area thoroughly to determine the
extent of the damage. Inspect the internal structure
for damage or signs of strain. Members that are bent,
fractured, or wrinkled must be replaced or repaired.
They may be sheared considerably without visible
evidence of such a condition. You should drill out
rivets at various points in the damaged area and
examine them for signs of shear failure.
During the inspection, note carefully all unusual
riveting problems or conditions that render riveting
difficult or make rivet replacement impossible. Any
fixtures that will hinder riveting and prevent the use
of straight bucking bars will be apparent in a thorough
inspection. There will also be places where flanges or
reinforcing members, intersection of stringers,
longerons, formers, frames, or rings make the bucking
of rivets very difficult. This problem can be solved by
designing and making bucking bars to suit these
particular situations.
You must take care to avoid mutilating the
damaged skin in the removal process. In some cases,
it can be used as a template for the layout and the
drilling of holes in the new piece of skin.
The rivet holes in stringers, longerons, bulkheads,
formers, frames, rings, and other internal members
must be kept in the best condition possible. If any of
these members are loosened by the removal of rivets,
their location should be marked so they can be
returned to their original position.
You should refer to the applicable repair material
chart in the aircraft structural repair manual for the
gauge and alloy of material to be used for the
replacement panel. The size and shape of the panel
Figure 13-64.—Flush access door installation.
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