NBAA Convention News

Honeywell's 731-50 is a low-risk venture

 - June 30, 2008, 7:20 AM

Honeywell launched the new TFE731-50 engine here in Orlando on Sunday evening, offering up to 4,900 lb of takeoff thrust and featuring integrated nacelle and thrust reverser systems. The new turbofan is set to achieve certification in 2004.

At a pre-NBAA show press conference on Sunday evening, Mike Redenbaugh, v-p and general manager of propulsion systems, said Honeywell is discussing new airframe applications with several undisclosed manufacturers. The most obvious retrofit candidates for the engine include the Dassault Falcon 900 and Falcon 20, the British Aerospace Hawker 800 and 1000, as well as the Bombardier Learjet 60. The company expects to actively pursue STC applications for the new engine in partnership with service centers.

“The -50 is a low-risk derivative of the current -60 production engine, utilizing a common core and a scaled wide chord damperless fan,” Redenbaugh said. “We expect the -50 engine will enter service with a 3,000-hour hot section (maintenance) interval and a 10,000-hour compressor zone interval.”

The -50 will draw on the technology used for the existing 731-60 engine, including the N1 DEEC system with hydromechanical backup, single-crystal blade material in the high-pressure and first-stage low-pressure turbines, as well as more effective cooling for the vanes and blades. The compressor is being designed to be more durable.

Honeywell also said here in Orlando on Sunday that seal and performance improvements for its TFE731-2/3/4/5 fleet have resulted in reliability levels that are more than three times the industry standard. Unscheduled engine removals for the so-called heritage series have now passed the 33,000-hr mark with the interval for the TFE731-4 model at 100,000 hr. The worldwide TFE731 family has now accrued more than 53 million hours of operations.

Meanwhile, Honeywell has just submitted documentation to have its new AS907 engine approved by Europe’s Joint Aviation Authorities (JAA). Tests are still in progress for the turbofan, which powers Bombardier’s new super-midsize Continental jet. Nacelle/integrated propulsion system tests, including inlet distortion and engine/nacelle acoustic evaluation, has now been completed.

According to Steve Loranger, president of Honeywell Engine Systems and Services, Honeywell’s goal is to have completed full Part 25 certification for the integrated powerplant system in time for the first units to be shipped later this year. The company is also seeking FAA approval for on-condition maintenance, claiming that this will represent “a level of reliability that no other business aviation engine in this thrust class can match.”

The AS900 family has so far accumulated more than 18,750 test hours (including the AS902 for the now-defunct BAE Systems Avro RJX regional jet), and Honeywell expects to have logged 22,000 hr by the time the 6,500-lb-thrust 907 enters service on the Continental next year. Ten AS907s are undergoing ground tests, with another 10 being flight-tested by Bombardier at its Learjet headquarters in Wichita. Each line replaceable unit is being subjected to severe operational cycle testing and combined thermal and vibratory testing to identify and remedy early life failure modes that have tended to cause headaches for operators.

New Civil Helicopter Engine Under Study

By year-end, Honeywell expects to have completed a 14-percent power upgrade to the LTS101 helicopter engine that powers the AgustaWestland EH 101 large transport. At the same time, it is now conducting “serious studies” into the possibility of launching a new 500- to 1,000-lb powerplant for the light rotorcraft market. Finally, next week should see the first flight of a Cessna Caravan utility turboprop powered by Honeywell’s TPE331 engine.