S.S. White Technologies is supplying flexible rotary shafts for the Honeywell Aerospace Air Turbine Starter (ATS) on the next-gen GE Aviation  GE9X high-bypass turbofan engines.

The Honeywell ATS comprises the starter and starter air valve. The flexible shafts are specifically designed to transmit rotary torque for the manual override of the starter air valve in case of an operational failure. The ATS is powered by complex turbo machinery to provide starting power to a gas turbine engine. Together, the components convert pneumatic energy to mechanical torque, which accelerates the engine to its required ignition speed.

The starter air valve controls air flow from the engine bleed, auxiliary power unit, or ground supply to the ATS and has significant built-in operational and protection features that reduce start-induced stresses to the engine. It also includes a high-temperature containment feature to reduce the risk of secondary collateral damage to personnel and machinery.

One of the features of the flexible rotary shaft is that it allows ground crews, if necessary, to manually actuate the starter air valve to enable aircraft dispatch. The ability to do so can prevent flight delays and cancellations further down the aircraft’s operational schedule.

S.S. White engineers utilize an in-house computer modeling software program to “more fully model the behavioral characteristics of the wire bundles within the shaft core” and provide “maximum bending flexibility and torsion strength while allowing minimal torsion deflection.” The company provides flexible rotary shafts for the aerospace, medical, industrial, and automotive industries.

The GE9X engine, which incorporates the Honeywell ATS and S.S. White flexible rotary shaft, is a derivative of the GE90 which was developed for the Boeing 777. Studies began on a more efficient variant, the GE9X, in February 2012 to power Boeing’s new 777X. The final GE9X design features a 3D-woven composite forward fan case and a 16-blade, carbon fiber 134-in diameter composite fan—wider than a Boeing 737 fuselage. The design also incorporates CMC (ceramic matric composite) materials in the combustor and high-pressure turbine, which GE claims will be a third of the weight, with greater thermal management capabilities, than a similar metal counterpart. The engine's force is currently rated at 105,000 lb.

GE recently conducted second-phase testing of the GE9X CMC components in a GEnx demonstrator engine. The components successfully completed testing in a dust and debris environment. GE9X Certification is still on target for certification by 2018, with introduction on the 777X planned for 2020.

Beyond S.S. White and Honeywell, several other partners will help contribute to deliver a combined total of 25% of GE9X components. IHI Corp. is responsible for the design and manufacturing of low-pressure turbine components, as well as the fan mid-shaft. IHI has participated on the CF34, GE90, GEnx, and Passport engine programs and has been producing GE military engines under license for more than 60 years.

France-based Safran Aircraft Engines will be designing and manufacturing the composite forward fan case and the turbine rear frame. Safran currently produces the CFM56 and LEAP engines with GE through CFM International and contributes to the CF6, GE90, and GP7200 programs. Safran Aero Boosters, will contribute to the GE9X with the design and manufacturing of the low-pressure compressor and will manufacture the fan disk. MTU Aero Engines AG is responsible for the GE9X turbine center frame.