Diamond DA 42 NG, Maintenance Manual

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AIRCRAFT
DA 42 NG AMM
Standard
Practices/Structures
Doc # 7.02.15
Rev. 4
51-10-00
Page 3
15 Mar 2018
4. Inspection Techniques
A. Visual Examination
Use this method to find all types of damage to composites. Use a bright light to examine visually
the inside of a component. GFRP must be green or brown in color. If it has white areas, then it may
be damaged. Look specially where components bond to the GFRP.
CFRP must be black in color. Apply a small load to the area where you expect a damage, e.g. by
pushing slightly on it. Check for abnormal flexibility or noises. Broken lamination often crackles
under load. Look specially in areas where components bond to the CFRP.
Look carefully at the outer surface of a component. If the paint has cracks or bubbles, then the
composite below may be damaged. Refer to Paragraph 5 in this Section.
Also look for dents and deformation. Look specially in the areas where stones can hit the fuselage
and wings below the airplane. Look specially in the areas of the wing walkways.
B. Light Test
Use the light test to find delamination. Use this test on components which do not have rigid foam
cores.
CAUTION: DO NOT LET THE COMPOSITE GET HOT. HEAT CAN CAUSE
DAMAGE TO COMPOSITES.
Point a very bright light at the surface and look at the surface from the opposite side to the light
source. Damage usually shows as dark areas in the component. You can point the light from the
inside of the component or the outside of a component.
Note: You can use the light test on thick sections of 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
across 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 in the area around the damage for secondary damage, which can remain
undetected.