From the Eurofighter to the Boeing 787, applications are growing in commercial and military aviation for sealant caps made by PPG Aerospace – PRC-DeSoto that afford time and labor savings and quality advantages for sealing fasteners, according to company officials.

Since their introduction in 2003, PRC seal caps by PPG have shown excellent adhesion with no sealant voids, and they are now being used for lightning-strike protection, according to John Sands, global business platform manager for aerospace sealants.

PRC seal caps are small caps molded from liquid PRC sealant that cures to form a flexible rubber shell. The cured caps are filled with more sealant, then frozen to arrest curing. The seal caps are thawed and applied over fasteners to cure, affording higher quality, less waste and better uniformity than traditional extruded application, according to Sands.

"Seal caps are becoming the sealant application method of choice in applications where consistent size, weight and quality are essential. In addition, the use of seal caps in hard-to-reach applications can minimize applicator strain, which also leads to improved quality," Sands said. "We now have more than 40 sizes to meet customer needs."

In addition to their use by Boeing on the 787 Dreamliner and Eurofighter consortium for the Eurofighter Typhoon, PRC seal caps are used by Cessna Aircraft Co., Hawker Beechcraft Corp. and Eclipse Aviation as well as by Lockheed Martin on the F-16 and C-17, Sands said.

With the success of PRC seal caps on the C-17, the U.S. Air Force is considering their use on other programs, including the B-52, Sands said.