Erickson S-64 Air Crane full composite main rotor blades

Erickson Inc. developed a more resilient, and cost-effective composite rotor blade for its S-64 Air Crane® helicopter with materials from Toray Advanced Composites. A six-blade heavy-lift helicopter certified in the 1960s, the S-64’s existing aluminum blades used expensive, antiquated WWII extrusion equipment that required time-intensive hand shaping and twisting in manufacture.

Erickson partnered with Toray Advanced Composites to develop a cost-effective composite rotor blade with lower maintenance costs and higher performance than legacy blades. At the time, FAA-approved composite materials for blades and their processes continued to be cost prohibitive. Toray Advanced Composites helped Erickson identify and receive qualification for materials and processes to develop higher performance rotor blades with significantly reduced manufacture and maintenance costs.

The Approval Process

Partnering early in the process with Toray Advanced Composites saved Erickson time, resources, and money. Toray’s BT250E-6 resin system was identified as the ideal candidate for Erickson’s design. Toray provided both carbon and glass reinforced composite materials in uni-directional and woven reinforced formats of the resin system for comprehensive NIAR testing and qualification. Key to this approval was demonstrating out of autoclave (OOA) processability, considerably reducing cost, tooling, and manufacturing time. All materials were qualified as autoclave and OOA capable with a 126°C (260°F) cure.

Design Development of the Composite Rotor Blade

The blades were designed with multiple layers of composites, each layer applied in a specific pattern and orientation to maximize strength and match the mechanical properties of the aluminum design, including:

• Aluminum mass and inertial properties
• Primary load tensile strength and stiffness
• Stiffness critical for flexion and flutter
• Shear strength and stiffness at the blade root

Each blade is cured OOA, consolidated with vacuum bag processing in an oven at Erickson’s composite manufacturing facility, built specifically to maintain control over composite blade production.

The Results

Toray Advanced Composites’ BT250E-6 resin system is the only OOA FAA-approved composite solution for rotor blades. A full design allowable database is now available for engineers to support future rotor blade design and manufacture.

Erickson’s new composite blades deliver:

• Improved production cycle
• Reduced initial and lifecycle operating costs
• Fuel savings and performance gains
• Dramatic reduction in engine torque required when lifting objects out of the water
• Dramatic reduction in vibration, especially during transition from forward flight to hover, resulting in less wear and fatigue on the whole airframe
• Increased flight comfort, reducing pilot fatigue

About Erickson

Erickson is a leading global provider of aviation services specializing in manufacturing, Maintenance Repair and Overhaul (MRO), defense and national security, and commercial aviation services. Erickson is the original equipment manufacturer (OEM) of the S-64 Air Crane® helicopter and the type certificate holder for the Bell 214ST & B/B1 platforms. Founded in 1971, Erickson is headquartered in Portland, Oregon, USA, and maintains operations in North America, South America, Europe, the Middle East, Africa, Asia Pacific, and Australia. For more information, visit: ericksoninc.com