Bonded patches with bond line control

1. A method of bonding a patch on structure, comprising:

placing the patch on the structure;

placing a layer of bonding adhesive between the patch and the structure;

placing a caul plate over the patch;

pressing the patch against the structure by applying pressure to the caul plate;

using an anti-caul plate to limit the pressure applied to a periphery of the patch by the caul plate; and

placing a non-reversible temperature indication strip on the anti-caul plate.

2. The method of claim 1 , further comprising:

placing a heat pack over the anti-caul plate, the nonreversible temperature indication strip, and the patch.

3. The method of claim 2 further comprising:

activating the heat pack to produce heat.

4. The method of claim 2 further comprising:

prior activating the heat pack, measuring a preactivation temperature of the heat pack with a first reversible temperature indication strip; and

raising the pre-activation temperature if the preactivation temperature is less than a desired temperature.

5. The method of claim 4 further comprising:

activating the heat pack; and

measuring a second temperature of the heat pack with a second, different reversible temperature indication strip.

6. The method of claim 5 further comprising:

if the second temperature fails to reach a second desired temperature, taking an action to increase the second temperature.

7. The method of claim 6 wherein the action comprises replacing the heat pack with a second heat pack and activating the second heat pack.

8. The method of claim 1 , wherein limiting the pressure applied to the periphery of the patch includes a reacting force applied to the caul plate around a perimeter of the caul plate.

9. The method of claim 1 , wherein the reacting force includes placing an anti-caul plate between the caul plate and the structure at the perimeter of the caul plate.

10. The method of claim 1 , further comprising:

placing a spacer between the patch and the structure to maintain the layer of bonding adhesive at a desired thickness.

11. The method of claim 10 , wherein placing a spacer between the patch and the structure includes introducing beads into the adhesive, each of the beads having a dimension generally equal to the desired thickness of the layer of bonding adhesive.

12. The method of claim 10 , wherein placing a spacer between the patch and the structure includes introducing a screen between the patch and the structure having a thickness generally equal to the desired thickness of the layer of bonding adhesive.

13. Apparatus for adhesively bonding a patch on a structure surface, comprising:

a caul plate adapted to be placed on and apply pressure to the patch during a bonding operation; and

an anti-caul plate between the caul plate and the structure surface, the anti-caul plate configured to limit an applied pressure to a periphery of the patch by the caul plate; and

a non-reversible temperature indication strip on the anti-caul plate.

14. The apparatus of claim 13 further comprising:

a heat pack placed over the anti-caul plate.

15. The apparatus of claim 14 further comprising:

a first temperature indicator strip on the heat pack and configured to indicate a pre-activation temperature of the heat pack; and

a second temperature indicator strip on the heat pack and configured to indicate an activated temperature of the heat pack.

16. The apparatus of claim 13 , wherein the anti-caul plate substantially surrounds the patch.

17. The apparatus of claim 13 , wherein:

the anti-caul plate is substantially circular and circumscribes the patch, and a perimeter of the caul plate overlies and engages the anti-caul plate.

18. A method of reworking a composite aircraft structure in the field, comprising:

preparing an area of the structure to be reworked;

forming a patch including forming perforations in the patch;

applying a layer of adhesive to one of the patch and the structure;

controlling a thickness of the adhesive layer by placing a spacer between the patch and the structure;

applying the patch to the structure;

placing a caul plate over the patch;

placing an anti-caul plate between the caul plate and the structure;

placing a non-reversible temperature indication strip on the anti-caul plate;

installing a pressure applicator over the combination of the patch, the caul plate and the anti-caul plate;

using the pressure applicator to apply pressure to the patch through the caul plate;

using the anti-caul plate to limit the pressure applied by the caul plate to a periphery of the patch;

installing a heat pack over the patch; and

using the heat pack to cure the adhesive.

19. The method of claim 11 , wherein placing a spacer between the patch and the structure also includes introducing a screen together with the beads between the patch and the structure, the screen and the beads both having a thickness generally equal to the desired thickness of the layer of bonding adhesive.