Bell OH-58A Technical Manual page 74

TM 55-1520-228-BD
AIRFRAME
g.
Evaluation of Damage to Skin and
Web Panels. Classify a skin or web
panel as failed if any of the following
conditions exist:
(1) Damage exceeds the limits con-
tained in Tables 4-2 thru 4-7, or if
damage is not tabulated and exceeds 25
percent of the panel area.
(2) Damage to one panel is located
within 3 inches of damage in an adjoin-
ing panel.
(3) The panel is severely deformed
or buckled.
(4) Damage to a panel exceeds the
damage limit. The damage extends across
a stringer, frame, or former in an ad-
joining panel. Classify that panel as
failed even if its damage is within
limits.
(5) The panel is on the outside of
the aircraft where the damage is exposed
to aerodynamic forces that can produce
peeling or tearing of the structure in
flight.
(6) Fasteners securing the panel
are sheared, pulled-through, or missing
at three or more adjoining locations.
(7) Twenty percent or more of the
total number of fasteners are similarly
damaged.
h. Evaluaton of Damage to Honeycomb-
Sandwich Panels.
sandwich structure as failed if any of
the following conditions exist:
(1) Damage exceeds limits
tabulated in Tables 4-2 thru 4-7.
(2) The panel is damaged to the
extent that it cannot support the weight
of personnel, cargo, or equipment for
which it was designed.
(3) The panel is on the outside of
the aircraft where it is exposed to
aerodynamic forces, and the damage is
4-30
Classify a honeycomb-
oriented so as to produce peeling or
tearing of the structure in flight.
(4) The panel is secured by mecha-
nical fasteners. Three or more
adjoining fasteners are sheared, pulled-
through, or missing.
(5) Twenty percent or more of the
total number of fasteners are similarly
damaged.
i. Evaluation of Damage to Sheet
Metal Ribs, Formers, Intercoastals, and
Channels. Classify a rib, former,
intercostal, or channel as failed if
any of the following conditions exist:
(1) Damage exceeds the limits con-
tained in Tables 4-2 thru 4-7, or if
damage is not tabulated and exceeds 25
percent of the structural section.
(2) Fasteners securing the com-
ponent are sheared, pulled-through, or
missing in three or more adjoining loca-
tions.
(3) More than 20 percent of the
total number of fasteners are similarly
damaged.
Evaluation and Damage to Hatches,
j.
Doors, and Door Jambs. Classify a
damaged hatch, door, or door jamb as
failed if any of the following con-
ditions exist:
(1) Damage exceeds limits
tabulated Tables 4-2 thru 4-7.
(2) Damage to the hatch, door, or
door jamb prevents it from being secured
adequately to the airframe.
(3) Hinges and latches are damaged
and in danger of becoming unserviceable
in flight.
(4) The hatch or door shows signs
of severe overstress such as buckling or
misalignment.