PPG Aerospace, SMRC develop sealant system for precoating aviation fasteners

PPG Aerospace – PRC-DeSoto and Systems and Materials Research Corp. (SMRC), Austin, Texas, are developing a system for precoating aircraft fasteners with sealant that will eliminate the need to apply wet sealant at the point of installation for labor savings, enhanced quality and reduced waste, according to the companies' officials.

PPG and SMRC have signed a letter of intent to partner on the development of the QwikSeal system, a process in which sealant is preapplied to aircraft fasteners, according to John Sands, PPG Aerospace global business platform manager, sealants.

"Sealant is typically hand-applied to aircraft fasteners before installation to reduce corrosion and provide a moisture or fuel barrier," Sands said. "With airplanes having hundreds of thousands – in many cases millions – of fasteners, it's an extremely labor-intensive process, and quality is highly variable. This unique approach of precoating the fastener with cure-arrested sealant has the potential to reduce labor by up to 20 percent over conventional wet installation while providing consistent quality."

In the QwikSeal system, sealant is machine-applied to the fastener, then overcoated with a moisture-barrier coating that prevents it from curing until the fastener is installed, Sands explained. When the fastener is driven into the metal or composite, the installation stresses crush the coating, allowing the sealant to fully cure.

Sands said the sealant-coated fasteners are undergoing further testing and factory evaluation before commercialization.

The technology represents a totally new approach that combines PPG's aerospace sealant expertise with SMRC's nanotechnology and material science core competencies, Sands said. Fasteners can be precoated with PPG's polysulfide, polythioether or non-chromated corrosion-inhibitive sealants.

"Conventional wet installation is a headache for airframers and maintainers," said Gary Schmidt, SMRC's vice president of product development. "With the QwikSeal system, we will simplify their lives and take a lot of the touch labor and waste out of the process for installing and sealing fasteners. Just about any kind of fastener, solid, threaded or blind, can be preprocessed with no changes to the hole, the fastener or the tooling."