Once a composite part is repaired, it is cured, inspected and finished. Though these processes are the essentially same ones used for initial fabrication of parts, they are critical. “The curing step is incredibly important,” says Busel. “Without curing, the repair is garbage: Just think of using a glue to paste two things together that never really bond.”
Finishing the part can be as simple as sanding and cleaning to sealing and painting with epoxy- or polyurethane-based coatings. For aircraft and wind turbines, conductive coatings that provide lightning strike protection are likely required.
The effectiveness of repairs depends on the skilled hands of technicians. In the past, composites repair technicians learned through trial-and-error or on-the-job training, says Dorworth. Composites manufacturers assigned repairs to their most skilled personnel. But now they recognize the importance of training dedicated composite repair technicians. Aerospace companies, including Boeing and Airbus, have led the way in repair technology and training.“Many aerospace OEMs are actively sharing best practices with other users of advanced composites,” says Dorworth.
He adds that the most popular course offered at Abaris is Advanced Composite Structures: Fabrication & Damage Repair Phase I. ACMA offers the Certified Composites Technician – Wind Blade Repair (CCT-WBR) to meet growing demand for training technicians in servicing and repairing wind turbines. To date, more than 100 people have earned the certification. (For more information on the CCT program, email Caitlin Felker at firstname.lastname@example.org.)
“We are now seeing community colleges and other training organizations offering composite-related repair curriculum,” says Dorworth. “It’s been 25 years in the making, but best practices are evolving around many industries, with aerospace technologies leading the way.”