(3) Inspecting for Structural Changes.
(a) Structural Changes. Inspect for
structural changes when the aircraft has taken an HEI
hit or the aircraft has flown with primary structure
damaged or missing. Inspect both the damaged
structure and the surrounding undamaged area for
evidence of buckling, crippling, and misalignment. This
type of damage is usually revealed by kinks and
wrinkling and "oil canning" of skin panels. Sheared,
indications of structural changes.
(b) Buckling, Crippling, and Misalignment.
Structural changes in the form of buckling, crippling, and
misalignment can happen as a result of blast pressures.
These could be associated with a HEI attack or as a
result of the overstress placed on a member. Such
members may have to carry the load of another
member which has been broken or crippled by projectile
damage. This type of damage can be critical to the
structural performance of a member and may also
cause interference of a member and may also cause
interference with mechanical moving components which
may bind or jam. This is especially true when the
member has to support compression loads. A stringer
that has been damaged can continue to support some
tension; for example, but may be completely ineffective
(c) Twisting or Bowing. Examine the
component for alignment and signs of twisting or
bowing. Use a straight edge to inspect these conditions.
(4) Inspecting for Embedded Projectiles and
Embedded Projectile. The effect of
an embedded projectile or fragment in a tension
member can be as that of a hole or crack of the same
size. The embedded object creates an interruption in
the structural section. Since it is difficult to detect, it
must be assumed that the projectile has nearly gone
through the structure.
Inspect for embedded projectiles and fragments when
either of the following conditions occur:
1 The aircraft has suffered HEI
2 Inspection of the aircraft indicates
that a solid projectile has not exited the aircraft, has
broken apart, or has created shrapnel by striking internal
(c) Projectile Path Determination. The
determination of projectile paths will aid in identifying
projectiles or fragments. Inspect all structures in the
region using a bright light and magnifying glass. Clearly
mark embedded objects and record them on DA Form
2404, Figure 2-4.
(5) Inspecting for Fire Damage.
(a) Armor Piercing Incendiary (API) and
HFI Fire Damage. The API and HEI threats include the
possibility of fire damage. These threats have a fire-
starting capability if flammable materials are present.
(b) Fire Effects. Some fires may not
adversely effect metal airframe structures. When
aluminum is exposed to temperatures above 300°F
(149°C) for a prolonged period, the temper and strength
of the material will be reduced.
(c) Initial Fire Damage Evidence. The first
signs of possible fire damage will be a discoloration of
the structure. Any discoloration indicates that the
member has been exposed to high temperature.
Conduct a hardness test to determine if the temper of
the material has changed. Such tests should be
conducted in accordance with standard practices. If a
information on DA Form 2408 and dearly mark the
(6) Detecting Substructural Damage in Adjoining
(a) Secondary Damage. When the
airframe has been subjected to severe overstress,
members undamaged by projectiles may bend or
buckle. This might be caused by explosive blast or
maneuvering loads imposed on damaged structures.
Sometimes this secondary damage will occur in a region
away from the primary area of damage. The airframe
near the projectile damage should be inspected for
evidence of secondary damage.
(b) Secondary Damage Indicators. Inspect
the skin for creases, wrinkles, and dents. Inspect
fasteners for chipped or flaked paint, looseness, and
serviceability. These conditions are signs of damage to
structure. Open or remove access panels and doors,
determine whether the frame is warped, and inspect the
interior members for cracks and structural changes.
Clearly mark and record all damage.