back up the material while driving out the pin. If
inaccessibility prohibits this, partially remove the
rivet head by filing or with a rivet shaver. An
alternative would be to file the pin flat, center punch
the flat, and carefully drill out the tapered part of the
pin forming the lock.
2. Pry the remainder of the locking collar out
with a drift pin.
3. Use the proper size drill to drill almost
completely through the rivet head.
1/8-inch-diameter rivet, use a number 31 drill; for a
5/32, use a number 24; and for a 3/16, use a
4. Break off the drilled head with a drift pin.
5. Drive out the remainder of the rivet with a pin
that has a diameter equal to or slightly less than the
AIRCRAFT METALLIC REPAIR
Learning Objective: Recognize the causes of
damage to metallic structures and the
procedures for their repair.
One of the most important jobs you will
encounter is the repair of damaged skin and material.
All repairs must be of the highest quality and must
conform to certain requirements and specifications.
You must be familiar with the principle of
streamlining, the behavior of various metals in
high-velocity air currents, and the torsioned stress
encountered during high-speed flying and
When any part of the airframe has been damaged,
the first step is to clean all grease, dirt, and paint in the
vicinity of the damage so the extent of the damage
may be determined. The adjacent structure must be
inspected to determine what secondary damage may
have resulted from the transmission of the load or
loads that caused the initial damage. You should
thoroughly inspect the adjacent structures for dents,
scratches, abrasions, punctures, cracks, loose seams,
and distortions. Check all bolted fittings that may
have been damaged or loosened by the load that
caused the damage to the structure.
Causes of Damage
Damages to the airframe are many and may vary
from those that are classified as negligible to those
that are so extensive that an entire member of the
airframe must be replaced. The slightest damage
could affect the flight characteristics of the aircraft.
The most common causes of damage to the airframe
are collision, stress, heat, corrosion, foreign objects,
fatigue, and combat damage.
COLLISION.This type of damage is often the
result of carelessness by maintenance personnel. It
varies from minor damage, such as dented or broken
areas of skin, to extensive damage, such as torn or
crushed structural members and misalignment of the
aircraft. You should exercise extreme care in all
CORROSION.Damage to airframe components
and the structure caused by corrosion will develop
into permanent damage or failure if not properly
treated. The corrosion control section of the
maintenance instructions manual describes the
maximum damage limits. These limits should be
checked carefully, and if they are exceeded, the
component or structure must be repaired or replaced.
FATIGUE. This type of damage is more notice-
able as the operating time of the aircraft accumulates.
The damage will begin as small cracks, caused by
vibration and other loads imposed on skin fittings and
load-bearing members, where the fittings are
FOREIGN OBJECT.This damage is caused
by hand tools, bolts, rivets, and nuts left adrift during
ground operations of the aircraft. Because of jet
aircraft design, large volumes of air are required for
its efficient operation. During ground operations, the
inlet ducts induce a strong suction that picks up
objects that are left adrift. Therefore, it is of utmost
importance that the area around the aircraft be clean
and free of foreign material before ground operations
COMBAT.Damage from enemy gunfire is
usually quite extensive and often not repairable.
When a projectile strikes sheet metal, it heats the
metal in the vicinity of the damage. The metal