TABLE OF CONTENTS Carbon/epoxy (and other similar) composite airframe components are immune to the costly forms of deterioration, notably cracking and corrosion, that plague aluminum and most other alloys used in airframe structures. However, these composites are much more easily damaged in service, for example, by mechanical impact. Thus repairability of such damage [1], [2] is an important consideration in the selection of composites for aircraft applications.
Table 10.1 lists the major sources of service damage. These include:
Mishandling
Impact, for example, by dropped tools
Contact damage in doors, often caused by poor rigging
Delamination damage, often caused by inadequate shimming during component assembly
Delamination caused during fastener removal or reinstallation
Local overheating caused by impingement of hot exhaust gases or from a lightning strike
| Defect | Typical Cause |
|---|---|
| Manufacturing Defects | |
| Voids | Poor process control |
| Delaminations | Inclusion of release film |
| Poor process control | |
| Faulty hole-drilling procedures | |
| Poor fit of parts during assembly | |
| Surface damage | Poor process control |
| Bad handling | |
| Misdrilled holes | Incorrect drilling procedure |
| Faulty jigging | |
| Mechanical Damage | |
| Cuts/scratches/abrasions | Mishandling |
| Penetrations | Mishandling/battle damage |
| Abrasion | Rain/grit erosion |
| Delaminations/disbonds | Impact: tools/hailstones/runway stones |
| Freeze/thaw expansion | |
| Aerodynamic peeling | |
| Overload, e.g., during assembly or removal | |
| Lightning strike/static discharge/laser/overheat | |
| Disbonds | Degradation of metallic interfaces, adhesive joints |
| Hole elongation | Fatigue-induced bearing failure, mechanically fastened joints |
| Dents/crushed core | Mishandling/impact |
| Edge damage, doors, etc. | Poor fit/mishandling |
| Environmental Damage | |
| Surface oxidation/burns | Lightning strike/laser/overheat |
| Core corrosion | Moisture... |
