PPG Industries' (NYSE:PPG) United Kingdom aerospace centre has created a novel solution for BAE Systems to seal aluminium box sections in the rear fuselage of Typhoon aircraft by casting sealant into precise shapes to channel moisture that forms during flight into drain holes.

PRC Drainblock seals by PPG Aerospace are cast in 30 precise shapes at the Shildon, U.K., Application Support Centre, packaged in cases that protect and identify the parts, and delivered to BAE Systems' Samlesbury site. PPG manages weekly delivery and pickup of the returnable cases.

This is the first known commercial application for this type of preformed sealant on an aircraft, according to Dick Surtees, PPG Aerospace account manager at the Shildon ASC. Surtees coordinated design and production of prototypes and oversaw the initial production runs with BAE Systems' design, materials and processes, and operations staff. He said he estimates that PRC Drainblock seals afford BAE Systems about a 50-percent labour time savings over casting epoxy fillers in position on the airframe. "The problem of channelling away moisture is not unique to Typhoon aircraft but can occur with any airframe," Surtees said. "The solution of using preformed sealant pieces is unique, as far as we know, but it may have application for others in the industry."

Because the sealant used to cast and apply the PRC Drainblock seals is already qualified and used on other parts of the Typhoon airframe, additional qualification was not required, Surtees said. The sealant pieces are cast from PR-1770A polysulfide fuel tank sealant, which is also used as the adhesive.

According to John Sands, PPG Aerospace global business platform manager for aerospace sealants, PRC Drainblock seals demonstrate PPG's ability to work with customers to create innovative ways to seal aircraft that may benefit additional aircraft manufacturers, operators or maintenance operations.

"Through our Customized Sealant Solutions program, we can provide customers with products that meet traditional sealing, smoothing and corrosion-inhibiting requirements while adding value by enhancing quality and reducing labour time," Sands said. "There is an immediate benefit to the customer, and the solution may be applicable elsewhere."

A growing number of Customized Sealant Solutions are becoming standard PPG products, Sands said. They include PRC seal caps, which are small caps moulded from liquid PRC sealant cured to form a flexible rubber shell, filled with more sealant, frozen and thawed to apply; FIP Strip sealant tape, a fast-curing, easy-to-apply polysulfide formed-in-place sealant tape; Semfoam dry bay foam, which is die-cut reticulated polyurethane foam, impregnated with sealant, frozen and thawed to apply; and Semplug sealant for sealing joggles and structural gaps.