Original Date: 10/14/1988
Revision Date: 01/18/2007

Bell Helicopter Textron, Inc. (BHTI) has successfully modified and adapted commercial filament winding systems to produce its family of complex rotor system components.

Filament winding techniques and processes have been developed for use in the fabrication of complex, highly loaded structural rotor system elements. Filament winding systems from Ingersoll, McClean Anderson and Goldsworthy Engineering are being utilized to produce rotor blade spars and highly loaded straps for yoke assemblies. In addition, filament winding is being used to produce conversion spindles for the V-22 aircraft.

Polar winding is utilized to wind major tension load straps for lug attachments in yokes and end fittings of rotor blades. In the case of rotor blades the thick straps for lug attachments are transitioned and shaped to form the spar shell, which is usually a relatively thin walled D-spar. Numerous ply packs and localized filler pad build-ups are also produced by polar wrapping of prepreg tow materials. Unique to the polar winding process utilized by BHTI is the ability to transition and shape the unidirectional tows during winding in the x, y, and z directions through the use of innovative tooling and compaction aids.

More conventional methods of filament winding are used to produce other parts such as the conversion spindle and control tubes. The winding approaches used are standard within the industry, but part specific steps dependent on subsequent part processing methodology. Several parts produced by filament winding are cured in closed female tooling. To eliminate part shrinkage and fiber movement during cure, each torsional or helical wrapped ply is slit longitudinally prior to cure. This allows outward part growth against the female tool during cure while maintaining proper fiber alignment.

For more information see the Point of Contact for this survey.