Diamond Aircraft DV 20 E 2022, Airplane Maintenance Manual

Page: 635 / 903

AIRCRAFT
DV 20 E AMM
Standard Practices and
Structures
Doc # 4.02.25
Rev. 2
51-10-00
Page 3
15 Mar 2022
B. Light Test
Use the light test to find delamination. Use this test on components which do not have rigid foam
inside.
CAUTION: DO NOT LET THE COMPOSITE GET HOT. HEAT CAN CAUSE
DAMAGE TO THE COMPOSITE.
Point a very bright light at the surface and look at the other side of the surface. Damage shows as
a dark area. You can point the light from the inside of a component or from the outside of a
component.
Note: You can use the light test on thick GFRP but it is difficult to use on CFRP.
C. Coin Tap Test
Use the coin tap test to find delamination and disbonding. Tap a coin on the laminate surface in the
area you will test. The sound of the coin tapping on the surface of the laminate will change as you
move the coin over damaged laminate.
Look specially at the area around the damage for secondary damage, which can remain
undetected.
5. Further Inspection
If you find paint damage when you examine a composite structure then do this further inspection.
Find a way to see the inside of a structure or a component. If necessary, remove panels (or other
components), or you can use remote viewing equipment. If you can see damage inside the component
or structure you must do a repair.
Remove the paint coat in the area that you think is damaged. Remove the paint coat carefully, you
must not damage the cloth under the paint coat.
Look carefully at the surface. If you find cracks in the composite you must repair the structure.
If you do not find cracks in the composite then do this test. Push the middle of the area to be tested
with your thumb. If you can feel the skin hitting the core of a sandwich (or other layer/component), then
the skin is disbonded and you must repair the structure.
In some cases you must cut inspection holes in the structure to do the test correctly. If you must cut
inspection holes you must seek advice from Diamond Aircraft Industries.