S.S. White Technologies, which supplies flexible rotary shafts for most of the major aircraft powerplants in production, is celebrating its 175th anniversary this week at the Paris Air Show.
Originally founded as a tooth manufacturer by Samuel Stockton White in 1844, the Philadelphia-based company (Hall 6 Stand C11) obtained its first patent for a flexible shaft in 1879 and began supplying flexible-shaft assemblies for military aircraft in 1941.
Today, nearly all commercial and military aircraft platforms (with the exception of Russian-produced aircraft) and half of U.S.-manufactured cars use S.S. White Technologies' flexible-shaft products.
The shafts transmit power to activate and synchronize power of the thrust reverser actuation systems on all CFM LEAP-series turbofans that power the Airbus A320neo and the Boeing 737 Max, as well as the new O-Duct thrust reverser system on the LEAP-1C engines powering the Comac C919. In addition, other applications for the flex shafts include the Rolls-Royce Trent 1000 aboard the Boeing 787, Trent XWB on the Airbus A350, and GE9X on the Boeing 777X, as well as the Pratt & Whitney GTF turbofans on the Airbus A220, A320neo, Embraer E180-E2, and Mitsubishi M90 and M100.
On many of these engines, the shafts transfer power to synchronize the actuators that expose the “cascade” vanes under two-piece D doors in reverser units upon landing.
For the GE9X, the shafts are designed to transmit rotary torque during manual override of the Honeywell Aerospace air turbine starter's air valve. The override allows ground crew to direct air flow from the engine bleed, APU or ground supply to the air turbine starter. Ground crew can thereby ensure an aircraft can be dispatched on time if there is a problem preventing a normal start procedure.