Technical data

13773-001
51-20
Page 38 30 Nov 2000
(4) Inner Laminate Repair
WARNING:
Always use twice as many repair plies as the original lay-up in order to
assure that the original strength is achieved.
(a) If there is a hole in the inner laminate, trim the damaged laminate back until all damaged
laminate is removed.(See Figure 51-201)
Note: If there is a hole in the inner laminate, make and attach a backing plate. If the
inner laminate is cracked or delaminated, but there are no large holes, the repair
plies will be applied over the damage.
(b) If required, manufacture and bond a backing plate into position. (Refer to 51-20)
(c) Make templates for each ply of the repair.
(d) Cut repair plies using templates.
(e) Sand the edge of the inner laminate to a 50:1 taper using 80-grit sandpaper.
(f) Remove all dust and debris with clean oil free compressed air and a vacuum.
(g) Check for any separation of the laminate to the core. Continue to sand back until all sepa-
rated laminate is removed.
Note: Never pour cleaning solvent directly onto laminate. Pouring solvent directly
onto a laminate surface will allow the laminate to soak up the solvent.
Moisten cloth with cleaning solvent to prevent the laminate from soaking up
the cleaning solvent.
(h) Solvent clean bonding surfaces of inner laminate with isopropyl alcohol. (Refer to 20-30)
(i) Use MGS L418/418 resin and lay up repair plies. Lay-up plies over center of puncture on
inner laminate.
(j) Perform full post-cure of repair plies. (Refer to 51-20)
(k) Continue repair with replacement of core. (Refer to 51-20)
(5) Pure Laminate Repair
WARNING:
Always use twice as many repair plies as the original lay-up in order to
assure that the original strength is achieved.
Pure laminate means there is no core present. Pure laminate, or inner laminate repair is similar
to repairing the outer laminate of a sandwich structure, the difference is, there is no underlying
surface to apply the repair to. A backing plate must first be constructed and attached to close
gaps or holes in the laminate. The backing plate is generally a thin, 2-ply laminate laid-up on a
surface with a contour similar to the repair area. A thin backing plate is flexible enough to con-
form to minor differences in shape. As soon as the extent of the damage is known, the backing
plate should be constructed.