be of the highest quality and conform to applicable technical manual
instructions.
Rib repairs are made by patching and insertion.
The
bent over position of a rib's flange and the vertical portion is the
web.
Specifications for each type of bulkhead damage are given in the
applicable manual for the aircraft.
Repair categories for bulkhead
damages are one-third or less of the cross-sectional area or more
than one-third of the cross sectional area damaged. If one-third or
less of the cross-sectional area is damaged, a patch plate,
reinforcing angle, or both many be used.
Details on the required
number of rivets can be obtained from the applicable technical
manual. For damage greater than one-third the area's cross section,
remove the entire section and make a splice repair.
For details on
the kind of splice and the number of rivets, consult the applicable
technical manual.
When repairs are made from flat sheet stock, its cross-sectional
tensile, compressive, shear, and bearing strength must be equal to or
greater than the original material.
Curved repair parts made from
the flat sheet stock must be in an annealed state before forming and
heat treated before installation.
Leading edge damage generally involves nose skin, nose ribs,
stringers, and possibly the cap strip.
In such a case, an access
door is required to make the repair possible. Such a repair requires
installing insertions and splice pieces; making repairs to the cap
strip and stringer; and if the damage is severe, installing a new
nose rib and skin panel.
Leading edge repairs must be made as
prescribed in the applicable manual.
Although trailing edges are not structural members, they are highly
stressed, and their damage can be limited to one point or extended
over the length between two or more rib sections.
In addition to
collision or careless handling, trailing edges are subject to
corrosion from moisture.
Damage between ribs of the trailing edge is repaired with a filler
and an insert. Fillers are made of hardwood, fiber, or cast aluminum
alloy. Inserts are made of the same material as the damaged section
and shaped to match the trailing edge.
To secure the repairs, use
countersunk rivets and countersink the shop heads for smooth contour.
Damage at or near a rib is repaired in much the same way. Sufficient
material must be removed for a complete splice between ribs.
Generally, this takes two splices joined by an insert made of the
same kind of material as the trailing edge or of formed sheet stock.
85
AL0992
PART E:
STRUCTURAL SEALING
GENERAL
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