Evaluation of Composite Components on the Bell 206L and Sikorsky S-76 Helicopter 861671

Progress on two programs to evaluate structural composite components in flight service on Bell 206L and Sikorsky S-76 commercial helicopters is described. Forty ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin have been installed on Bell Model 206L helicopters that are operating in widely different climates. Component installation started in 1981 and selected components are being removed and tested at prescribed intervals over a 10-year evaluation. Four horizontal stabilizers and ten tail rotor spars that are production components on the S-76 helicopter are being tested after prescribed periods of service to determine the effects of the operating environment on their performance. Concurrent with the flight evaluation, materials used to fabricate the components are being exposed in ground racks and tested at specified intervals to determine the effects of outdoor environments. In this paper, results achieved from 73,000 hours of accumulated service on the 206L components and 50,000 hours on the S-76 components are reported. Six ship sets of 206L components have been removed and tested. Results of 5 years of ground exposure of materials used to fabricate the 206L components are presented. Results of tests on three S-76 horizontal stabilizers and seven tail rotor spars are presented. Panels of material used to fabricate the S-76 components that were exposed for 4 years have been tested and results are presented.


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