NBAA Convention News

Williams Keeps Quiet About Engine Features

 - October 23, 2014, 4:00 PM

Pilatus and Williams International have been touting some features–passive thrust vectoring and quiet power mode–of the FJ44-4A turbofan on the PC-24 but the engine manufacturer is scarce on details. The so-called Exact passive thrust vectoring system uses “a proprietary fluid dynamic scheme,” Matt Huff, Williams’ business development vice president, told AIN. The thrust vector from the exhaust nozzle varies as a function of engine operating conditions–power setting, exhaust gas temperature, Mach number and altitude. As the benefit can be seen in performance and efficiency, “it adds much less weight than what it typically saves,” Huff asserted. The technology is said to have been validated through flight tests several years ago.

The quiet power mode enables an engine to be used like an auxiliary power unit (APU) on the ground, providing electric power and bleed air (that is, hot, compressed air). AIN understands that this mode has only the high-pressure spool running, keeping the low-pressure shaft (and thus the fan) still.

“The noise signature of our quiet power mode is less offensive than typical APUs,” Huff said. The weight, as well as acquisition and maintenance costs, are estimated to be a fraction of that of a traditional APU. Development testing is complete, according to Huff.

The PC-24, the first business jet from Pilatus, rolled out of the company’s Stans, Switzerland factory on August 1 and is expected to be certified in 2017.