Guy Norris/LOS ANGELES
ALLIEDSIGNAL ENGINES is studying upgrades to a series of engines used in the corporate-aviation sector, following the success of its TFE731-3C effort for the Cessna Citation III and VI and the recent launch of the -3D upgrade for use on other types of business jet.
"We're studying every engine", says AlliedSignal Engines new- products marketing director George Purpura. This is based partly on the "tremendous acceptance," of the -3C upgrade on the Cessna fleet, he says. Some 383 engines out of a fleet of 450 have so far been converted.
"We anticipate up to 95% of the fleet will eventually be upgraded," says Purpura.
"With that as an indicator, and the -3D being applicable to all -3 applications, we're looking at every engine in the fleet," he adds. The upgrade study, which encompasses engines including the TFE731-/2/4/5 and 5A, is aimed at encouraging brand loyalty as well as staving off growing competition, particularly from Pratt & Whitney Canada.
In June, the company expects to begin the first of up to 80 -3D modifications planned for 1996 (Flight International, 10-16 April). "We're spooling up our facility to be able to handle around ten conversions a month, and we will evaluate the potential for more depending on demand," says after-market programmes director Jim Donlan.
Initial -3D upgrades will focus on engines powering Dassault Falcon 50s and Raytheon Hawker 400s, 600s and 700s.
Later modifications will involve the Israel Aircraft Industries Westwind and the Rockwell Sabreliner 65/65A. Around 3,000 engines are eligible.
"We're giving operators a range of options," explains Donlan. The company's "three-pronged" approach allows TFE731-3 users to modify their engines by incorporating individual service bulletins, or AlliedSignal's suggested factory configuration, or by upgrading to the TFE731-3D model.
The upgrade results from studies, which began in 1992 to address "temperature limitations" and durability problems. Major elements include a new high-pressure (HP) turbine rotor, first-, second- and third-stage low-pressure turbine rotors, carbon seals, fourth-stage compressor disc and seal system and an improved-durability HP turbine nozzle assembly.
Another significant part of the upgrade, which consists of around 60 improvements, is a "controlled-fit" combustor. This is made from forged rings, which are claimed to retain a precision fit for the lifetime of the combustor.
"This makes sure you have zero performance loss through any misfit of the combustor after the upgrade," says Purpura.
The upgrade increases inter-turbine-temperature limits by 25¡C in climb and 20-36¡C in cruise, depending on airframe.
Source: Flight International
