General Bonded Fastener Removal
100207-00
Remove disbonded or damaged bonded fasteners and any remaining adhesive using the procedure below.
Applicable Aircraft Serial Numbers
All
Type of Maintenance
Line
Level of Certification
LSA-RM
Task Specific Training Required
No
Specific Tools Required
None
Parts Required
Many bonded fasteners are used in the
A5. These include:
CB3000 Large Metallic Base Stud
CB3021 Reverse-Mounted Stud
CB3033 Reverse-Mounted Standoff
CB4000 Large Composite Base Stud
CB4020 Composite Right-Angle Cable Tie Mount
CB5000 Small Metallic Base Stud
CB5001 Small Base Locking Thread Standoff
CB6007 Clip-Retained Corner Nutplate
CB6009 Clip-Retained 2-Lug Nutplate
CB6010 Sealed Two Lug Nutplate
CB9120 Low Profile Cable Tie Mount
CB9205 Strap Fastener
Aircraft System and Number
NA
Safety Equipment
As Needed
Consumables
None
Read these repair instructions in their entirety before starting. Any questions or uncertainties regarding interpretation of these instructions shall be forwarded to ICON Owner Support before any work is done.
All substrate materials must be protected from temperatures exceeding 200°F during the application of heat to soften the adhesive material attaching the fastener. Excessive temperatures can cause disbond, delamination, and blistering of composite substrates, resulting in a loss of strength and reliability.
CAUTION:
Temperature more than 200°F (93°C) can permanently damage the composite aircraft structure. Use extreme caution whenever using applied heat.
Use the following methods to prevent temperature damage
• Keep the maximum output air temperature of the heat gun below the threshold of damage of the substrate and any surrounding components (200°F).
• Use any available technologies (e.g. infrared thermometer, thermocouple, etc.) to monitor the temperature of the nearby substrate during the operation. It should always be below the threshold temperature of 200°F (93°C).
• Mask adjacent components and substrates with thermal barrier (e.g. silicone sheet) to minimize heat transfer to unintended areas.
Task Instructions
1. Cut a conformal mask from silicone rubber sheet (0.25-inch thick). The mask should extend a minimum of 3-inches beyond the fastener in all directions. In the middle of the mask, cut a minimally sized hole to permit access to the fastener intended to be heated and removed. Drape the mask over the fastener and secure with aluminum foil tape (3M 425).
2. Use a heat gun to heat the fastener for removal. Hold the heat gun at a 90° inclination to the fastener (perpendicular to the adhesion surface), and position it approximately one inch from the baseplate of the fastener. Center the airstream on the fastener base plate to soften the underlying adhesive.
3. Allow the heat gun to dwell above the fastener until the underlying adhesive softens (about 30 to 45 seconds). It may help to grip the fastener with pliers and apply a twisting load (twisting about an axis perpendicular to substrate surface) while the heat is applied.
4. Once the adhesive is soft, and before any cooling occurs, use pliers to grip and twist the fastener from the substrate. The twisting motion is important as it allows the initial bond to be broken with an in-plane load. An out-of-plane load, such as that generated by pulling or prying, is more likely to result in delamination damage.
5. If any adhesive remains on the substrate after fastener removal, use the same method to heat the remaining adhesive and use a hard plastic chisel or similar tool to wedge the adhesive off. Be careful not to damage the underlying or surrounding substrate during this operation.
Verification Method
Once all adhesive is removed, inspect the underlying substrate for damage (delaminations, blisters, broken fibers, cracks etc.).
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