Differential expansion of the fastener in the composite.
The effect of drilling on the structural integrity of the material, as well as delamination caused by fasteners under load.
Water intrusion between the fastener and composite.
Electrical continuity of the composite and arcing between fasteners.
Possible galvanic corrosion at the composite joint.
Weight of the fastening system.
Fuel tightness of the fastening system, where applicable.