Inspection Techniques - Diamond DA20-C1 Maintenance Manual

DA20-C1 AMM
6.

Inspection Techniques

There are different methods of inspecting a damaged composite area. The following gives the
procedures for inspecting a damaged Fiber Reinforced Plastic (FRP) area.
A. Examine Visually
Look carefully at the outer surface of an area or component. If the paint has cracks or bubbles,
then the composite may be damaged. Surface damage, e.g. dents or scratches may be detected
by visual inspection. Look especially in the areas where stones can hit the aircraft below the
fuselage and wings. By visual inspection, you can see where fiber breakage or matrix cracking has
happened. Damage to the core may also be visible.
A bright light can be used to visually examine the inside of a component. GFRP must be green or
brown. If the GFRP has white areas, then it may be damaged. Look especially at areas where
components bond to the GFRP.
Carbon Fiber Reinforced Plastic (CFRP) must be black or black/brown. If the CFRP has white
areas, then it may be damaged. Look especially at areas where components bond to the CFRP.
B. Light Test
A light test can be used to find delamination on components which do not have rigid foam inside.
CAUTION:
Point a bright light at the surface of the composite and look at the other side of the surface.
Damage shows as a dark area. You can point the light from the inside 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
Damage to the laminate can be detected by tapping a coin on the laminate. The sound of tapping
will change its frequency as you move over the damaged area in relation to the sound of other
areas of corresponding thickness. By performing a tap test, you can detect disbonds (the
separation of one component which is bonded to another component) and delaminations (the
separation of individual layers of the glass cloth).
Pay special attention to the area surrounding the damage, because there could be secondary
damage, which can remain undetected.
DA201-C1
Rev 21
DO NOT LET THE COMPOSITE GET HOT. HEAT CAN CAUSE DAMAGE TO
THE COMPOSITE.
51-00-00
Standard Practices - Structures
Page 5
14 Jan 13