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

Progress is described on two programs to evaluate structural composite components in flight service on Bell 206L and Sikorsky S-76 commercial helicopters. Forty ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin have been installed on Bell 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 11 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, the 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 123,000 flight hours of accumulated service on the Bell 206L components and 53,000 flight hours on the Sikorsky S-76 components are reported. Seventy-eight Bell 206L components have been removed and tested statically. Results are presented after 7 years of ground exposure of materials used to fabricate the Bell 206L components. Results of tests on 4 Sikorsky S-76 horizontal stabilizers and 11 tail rotor spars are presented. Panels of materials used to fabricate the Sikorsky S-76 components that were exposed for 6 years have been tested and results are presented.