Long before the mandatory cuts of 2013’s budget sequestration went into effect, original equipment manufacturers (OEMs) of government-purchased aircraft were finding ways to value engineer their products. That is, they were looking for ways­, and for suppliers – to create alternatives to traditional materials and manufacturing processes that would improve functionality and cost savings throughout the lifecycle of the aircraft they produced.

One such domestic rotary-wing aircraft manufacturer (anonymous by request) turned to RMB Products to find an innovative alternative to the composite and metallic environmental control system (ECS) ducting used in several of its helicopters.

The challenge for RMB Products was to develop an alternative process for manufacturing ECS ducting that would provide all the advantages and performance of composite and metallic ducting, reduce or eliminate their shortcom­ings and significantly decrease lifecycle costs.

The original ducting design specifications (from the 1970s) called for rectangular ducting with harsh 90-degree corners and sharp edges. By today’s standards, the ducting is unnecessarily bulky, fragile, and not optimized for fluid dynamics. RMB Products’ first task was to optimize the design of the ducting system using 3D CAD technology, instead of the original 20-drafted designs.

RMB Products’ second task involved material selection and formulation. Although composite layups (e.g., Kevlar-0) provide improved corrosion resistance, reduced drag, and better fatigue resistance compared with metals, composite ducting can be easily damaged when improperly handled and is susceptible to fraying, fracturing, and separation along with layers (delamination). RMB Products wanted to use an aerospace-grade thermoplastic material that would meet high standards of mechanical performance, impact resistance, long-term reliability, flame retardancy, and resistance to chemical attack.

A final task involved choosing a manufacturing process well-suited to economical low- to medium-volume production runs. Components made from composite materials are expensive and labor-intensive to produce, often requiring long lead times from manufacturers. RMB Products wanted a simple, turnkey solution that would shorten lead times, reduce required maintenance and provide other advantages such as reduced part counts, lower tooling costs, and increased service life.

RMB Products turned to rotational molding and its proprietary, flight-certified Nylon 12 polymer (RMB 437) to manufacture a superior alternative to the traditional composite ECS ducting. As one of the most versatile and cost-effective molding methods, rotational molding excels at producing the seamless, hollow components required in aircraft ducting systems.

RMB 437’s high resistance to impact, heat, brittleness, deterioration, and chemicals make it the preferred material for aircraft ducting. Nylon 12 performs better than other types of nylon because it absorbs less moisture and is dimensionally stable. RMB 437 Nylon 12 is highly resistant to impact, flame retardant (meets FAR 25.853 and FAR 29.853 12- and 60-second vertical burn requirements) and has a proven track record in the aerospace industry.

RMB Products invested $5,000 in completing its proposal for an alternative ECS ducting solution. The company – Redesigned one part of the ECS ducting system to adapt and optimize it for rotational molding – Created the necessary tooling for the part’s manufacture – Rotationally molded a dozen working samples for the GEM’s engineers to review and evaluate

RMB Products’ proposed solution for alternative ECS ducting was deemed highly successful by the rotary-wing aircraft OEM. Out of 10 projects, the OEM had lined up corporate-wide, RMB Products’ solution represented the top cost-savings opportunity, with almost a 70% reduction over traditional technologies and materials.

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