Story ID: 352
Honeywell's TFE731 Turbofan Engine Turns 50
By: Jerry Siebenmark
Caption: The TFE731, which turns 50, was Honeywell's first business jet engine.
Word Count: 540
Honeywell Aerospace marked a major milestone in August when its first purpose-built business jet engine, the TFE731, turned 50 years old. The turbofan engine, 13,000 of which have been produced to date, continues to power such jet types as the Dassault Falcon 900, Bombardier Learjet 70/75, and Gulfstream G150.
According to Honeywell, 9,400 of the engines remain in service today and in total have accumulated 108 million flight hours. The engine was designed to meet the specific needs of business jets while other engines from the era were adapted from existing military jet engines.
Honeywell's predecessor, Garrett (AlliedSignal), developed the TFE731 in the late 1960s to provide the nascent business jet market with an engine that would fly coast-to-coast without refueling and that was reliable. The engine also would lead to the development of the HTF7000 engine family that powers some current-production super-midsize jets, including the Gulfstream G280.
“The TFE731 has really set the bar and is recognized for its high reliability,” Honeywell Aerospace v-p of engines Hans Laudon told AIN. “And that extensive experience…and high bar of reliability continues now into our more current product platforms, which is the HTF7000 family.”
Besides being Honeywell’s first turbofan, the TFE731 also was the first geared turbofan engine with a dual-spool design—adapted from the technology used in the TSCP700 auxiliary power unit used on the McDonnell Douglas DC-10—to improve fuel efficiency and range.
“What that dual spool allows is for the fan, turbine, and compressor to be optimized for each of their respective rotational speeds versus all of them having to spin at the same rate,” Laudon explained. “That compact architecture the TFE731 represents still delivers today an engine cycle that is of optimum performance when you look at a thrust-to-weight ratio and from a fuel efficiency and range standpoint.”
Dassault and Learjet were the engine’s launch customers, later to be followed for use by other OEMs including Cessna, Lockheed, Israel Aerospace Industries, and Raytheon Aircraft/Hawker Beechcraft. Later adopted in military training aircraft such as the CASA 101 and AIDC AT-3, the TFE731 has received 34 type certifications and was produced in 80 configurations.
The engine’s efficiency has improved over time with the use of improved turbine materials that enable it to operate at higher temperatures, as well as digital engine controls, Laudon added. Since production of the TFE731-2 began in the early 1970s, the engine’s takeoff thrust has improved from 3,500 pounds to 5,000 pounds with the TFE731-60.
While Honeywell continues to produce the engine primarily for Dassault (for the Falcon 900LX), it may not be for long. “I do think we are beginning to see kind of the end of life from a production standpoint,” Laudon said.
However, he added, the engine will continue to be supported by Honeywell and its partners through modifications such as a connected data transfer mechanism that takes data from engine controls for engine assurance and proactive engine health monitoring.
“The way we think about our continued support of this platform along with our newer platforms like the HTF7000, we will continue to support and provide retrofit modifications,” Laudon said.
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