the flight status of the aircraft. Before classifying
Classification of Damage
damage as negligible, make sure the damage complies
After the extent of damage has been determined, it
with the manufacturer's specified limits of negligible
should be classified in one of the following categories:
negligible damage, damage repairable by patching,
DAMAGE REPAIRABLE BY PATCHING.--
damage repairable by insertion, or damage requiring
Damage that can be repaired by installing a
replacement of parts. See figure 4-56.
reinforcement or patch to bridge the damaged portion
Before proceeding with the repair of the airframe, it
of a part may be classified as a damage repairable by
is necessary that the applicable structural repair manual
patching. Reinforcement members are attached to the
be consulted for the procedures and materials to be
undamaged portions of the part to restore full
used. If the applicable manual is not available, the
load-carrying characteristics and airworthiness of the
General Manual for Structural Repair, NA 01-1A-1,
aircraft. Damage repairable by patching is specified for
may be used. If any conflict should exist between the
each member of the airframe.
two manuals, the specific manual takes precedence.
DAMAGE REPAIRABLE BY INSERTION.--
NEGLIGIBLE DAMAGE.--Negligible damage
Damage that is extensive enough to involve a major
is that damage or distortion that may be allowed to exist
portion of a member, but which is not so extensive as to
as is or corrected by some simple procedure, such as
require replacement, is classified as damage repairable
removing dents, stop-drilling cracks, burnishing
by insertion. You make this repair by inserting a new
scratches or abrasions, without placing a restriction on
section and splicing it to the affected member.
DAMAGE REQUIRING REPLACEMENT.--
Damage that cannot be repaired by any practical means
is classified as damage requiring replacement. Short
structural members usually must be replaced because
repair of such members is generally impractical.
DAMAGE REPAIR PROCEDURES
Damage repair procedures vary greatly from
aircraft to aircraft and the type of repair that is going to
be performed. Also consult the applicable aircraft
MIMs and the applicable aircraft structural repair
manual before performing any structural repairs.
Selection of Repair Material
The major requirement in making a repair is the
duplication of strength of the original structure. You
should consult the structural repair manual for the
aircraft concerned for the alloy thickness and temper
designation of the repair material to be used. This
manual will also designate the type and spacing of
rivets or fasteners to be used in the repair.
In some instances, substitutions of materials are
allowed. When you are making a substitution of
materials and conflicting information between manuals
exists, the structural repair manual for the aircraft being
repaired should be used.
Figure 4-56.--Classifications of damage.