TM 1-1500-204-23-11
the new hole depends upon how
against the control created in step (d) to
closely the rivet its the hole; if it is
ensure the adjustment has not changed.
a sloppy it, select a different type
of fastener with a larger diame-
(m) Drill the fastener holes. Pilot drill and
ter or have a machinist turn down
drill to inal size per paragraph 6-8.
a larger rivet to the diameter you
need to ill the hole.
f. Example Procedure For A Bolted Repair.
Do not scribe directly onto composite or metal.
If an aluminum patch plate is installed as a
Loss of structural integrity may occur.
permanent repair on a carbon structure, a
corrosion barrier, such as a ply of iberglass
Scribe an arc onto the speed tape
2
cloth or an approved sealant, must be installed
between the aluminum patch and the carbon
(g) Carefully place speed tape around the
epoxy structure. Refer to the system speciic
periphery of the panel.
technical manual for galvanic isolation of
aluminum.
(h) Put the replacement panel in place
and adjust the location as necessary to
NOTE
maintain gap tolerances. Secure the
panel.
The following drill procedure does not consider
curvature of the structure. Slight modiications
of the procedure may be required if more than
one patch layer is required.
Do not scribe directly onto composite or metal.
This paragraph represents the basic procedure
Loss of structural integrity may occur. See
for drilling a bolted patch to an existing structure
paragraph 6-20 to prevent galvanic corrosion.
where there are no existing fastener locations to
pick up and where no back side access exists.
(i)
From each of the arcs previously
If existing fastener locations exist, see the above
scribed, scribe two arcs onto the panel.
procedures for locating these fastener holes on the
The intersection of the two arcs is the
patch plate. This procedure is applicable for repair of
center of the fastener hole. Trans-
skin penetration damage occurring in thick monolithic
fer four fastener holes onto the panel,
composite structures. Modiications are necessary for
preferably one near each corner.
application to sandwich structure. This procedure uses
an external patch. See the system speciic technical
NOTE
manual for using this procedure for external/internal
The accuracy will be best when the two arcs
or internal only patches. Fastener holes must be
are scribed from locations that are 90 degrees
drilled in the patch and skin to complete a bolted
apart on the initial arc.
repair. Through these fastener holes, the repair
plate will be attached to the damaged area with
(j)
Remove the panel, pilot drill initial fas-
mechanical fasteners. For eficient load transfer, a
tener locations, and drill to inal size per
Class II tolerance (+0.0025/-0.000 inch) is generally
recommended for structural repairs in composites. The
following procedures and the guidelines in paragraph
(k) Install the replacement panel with fas-
6-8 for drilling and reaming are suggested for obtaining
teners or temporary fasteners in the ini-
the best quality holes. This repair procedure is
tial holes.
not necessarily applicable to a particular weapon
system. The applicability of this repair depends
upon additional factors such as loading conditions
and laminate thickness. Consult the system speciic
technical manual or engineering for further guidance.
Do not scribe directly onto composite or metal.
Process Flow Diagram. Refer to igure 7-27 for the
Loss of structural integrity may occur.
Process Flow Diagram for Penetration Damage Bolted
Repair, External Patch.
(l)
Transcribe the remainder of the fastener
locations using the arc method. Period-
ically, check the setting on the dividers
7-50
