areas of skin, to extensive damage, such as torn or
Q4-31.
What is the Navy standard countersink
crushed structural members and misalignment of the
angle?
aircraft. You should exercise extreme care in all
Q4-32.
A CP350 blind rivet tool is used to pull what
ground-handling operations.
type of rivet?
CORROSION.--Damage to airframe compo-
Q4-33.
When drilling out a self-plugging rivet, what
nents and the structure caused by corrosion will
size drill bit would you use to drill a 1/8-inch
develop into permanent damage or failure if not
rivet?
properly treated. The corrosion control section of
the maintenance instructions manual describes
AIRCRAFT METALLIC REPAIR
the maximum damage limits. These limits should
be checked carefully, and if they are exceeded,
LEARNING OBJECTIVE: Recognize the
the component or structure must be repaired or
causes of damage to metallic structures.
replaced.
Identify the procedures for repair of metallic
structures.
FATIGUE.--This type of damage is more
noticeable as the operating time of the aircraft
One of the most important jobs you will encounter
accumulates. The damage will begin as small cracks,
is the repair of damaged skin and material. All repairs
caused by vibration and other loads imposed on skin
must be of the highest quality and must conform to
fittings and load-bearing members, where the fittings
certain requirements and specifications. You must be
are attached.
familiar with the principle of streamlining, the behavior
of various metals in high-velocity air currents, and the
FOREIGN OBJECT.--This damage is caused by
torsioned stress encountered during high-speed flying
hand tools, bolts, rivets, and nuts left adrift during
and maneuvering.
ground operations of the aircraft. Because of jet aircraft
design, large volumes of air are required for its efficient
DAMAGE REPAIRS
operation. During ground operations, the inlet ducts
induce a strong suction that picks up objects that are left
When any part of the airframe has been damaged,
adrift. Therefore, it is of utmost importance that the
the first step is to clean all grease, dirt, and paint in the
area around the aircraft be clean and free of foreign
vicinity of the damage so the extent of the damage may
material before ground operations begin.
be determined. The adjacent structure must be
COMBAT.--Damage from enemy gunfire is
inspected to determine what secondary damage may
usually quite extensive and often not repairable. When
have resulted from the transmission of the load or loads
a projectile strikes sheet metal, it heats the metal in the
that caused the initial damage. You should thoroughly
vicinity of the damage. The metal becomes brittle
inspect the adjacent structures for dents, scratches,
around the damaged area as a result of the heat, and
abrasions, punctures, cracks, loose seams, and
minute cracks are created by the impact of the
distortions. Check all bolted fittings that may have been
projectile. These cracks open up under vibration. If the
damaged or loosened by the load that caused the
projectile passes through the component or structure, it
damage to the structure.
will leave a larger hole on the opposite side from where
it entered. The repair procedures for combat damage
Causes of Damage
should be followed with extreme care only after a rigid
Damages to the airframe are many and may vary
inspection of the damage has been completed in
from those that are classified as negligible to those that
accordance with the General Manual for Aircraft Battle
are so extensive that an entire member of the airframe
Damage Repair, NAVAIR 01-1A-39.
must be replaced. The slightest damage could affect the
HEAT.--Certain areas of high-performance air-
flight characteristics of the aircraft. The most common
craft are exposed to high temperatures. These areas
causes of damage to the airframe are collision, stress,
usually include the engine bleed lines, fuselage sections
heat, corrosion, foreign objects, fatigue, and combat
around the engine, the aft fuselage and horizontal
damage.
stabilizer, and the wing sections around the boundary
COLLISION.--This type of damage is often the
layer control system. Some aircraft structural repair
result of carelessness by maintenance personnel. It
manuals include diagrams that illustrate the heat danger
varies from minor damage, such as dented or broken
areas.
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