lack strength for use in primary structures.
formed in their annealed state first and then heat treated, in the
desired shape, to develop their strength. When using a brake to form
metal, be sure that a thin piece of soft metal is placed on the brake
jaws to prevent marring the metal's surface.
The best method for determining the size and number of rivets to use
on a repair is to refer to the direct and general support manual
applicable to the aircraft being repaired.
This manual gives the
and depot maintenance on the complete airframe.
All repairs must be made so that the aircraft's original contour is
In addition, all repairs must be kept to a minimum
This is accomplished by using patches as small as
practicable and limiting the number of rivets to what is necessary.
When weight is added in each repair, the aircraft's balance may be so
disturbed that trim and balance tabs may have to be adjusted.
patch on the propeller spinner requires a balancing patch to keep the
In making aircraft structural repair, the primary objective is to
restore the damaged parts to their original condition.
the only effective way is to replace the damaged part or parts.
However, each damage must be studied carefully to determine if
repairing or replacing is the course to follow.
If a damaged part
can be repaired, its purpose or function must be fully understood.
The reason for this is that while strength may be the principal
requirement in some structures, others might need totally different
characteristics. For example, fuel tanks, floats, and hulls must be
leak proof; however, cowlings, fairings, and similar parts must be
smooth and streamlined.
member stresses, and repair practices.
While inspecting damage, remember that all damage is not obvious
or limited to an immediate location. For example, skin damage
made by shells or shell fragments may be accompanied by damage
to longerons, struts, cables, and so on. A hard landing can
shock strut, see if the damage extends to supporting structural
members. When a shock occurs at one end of a member it
is transmitted the entire length of that member. Therefore, all