The Short Life and Untimely Demise of the PW8000
When I started in the Garrett engine shop back around 1980, Garrett was coming to the end of a long hard development slog, getting the gearbox right on the TFE731 turbofan. There had been numerous failures, service bulletins and planetary reworks, and every engine in the field had gone through the rework program. As I recall I was given a special tool for removing a large anti rattle washer on the sun gear, which was one of the last big service bulletins. The whole mess cost Garrett a lot of money, downtime, and ill will.
All of which made it more interesting when Avco Lycoming tried more or less the same thing on the ALF502-which also had significant teething problems and nearly sunk the Canadair Challenger program. The ALF502 was supposed to be a quick and dirty spinoff of the T53 military turboshaft engine-but it took a lot of engineering to make it serviceable.
The handwriting was and is on the wall-gear reduction fan drives in turbine aircraft engines are damned difficult to bring off. They're expensive, quirky, and beset with problems not easily fixed, and the development dollars mount rapidly.
So when I heard that Pratt & Whitney was working on geared fans, my ears perked up and I wondered whether the boffins at East Hartford were smarter than everyone else or just didn't bother reading the newspapers.
The PW8000 was supposed to be a geared fan section on a PW6000 power core, and the article in the SAE journal archives is most interesting. The engine was scheduled for certification two years on, which would have put the release date about 2001. There is also a very nice article in Flug Review which described the history and construction of the PW8000.
But the PW8000 never went anywhere despite ten years of research and $350 million in development money.
The latest iteration of the geared fan concept from Pratt is their GTF Demonstration program which they are currently working on at this writing. It is a PW6000 core with a revised planetary gearbox that is alleged to save weight and be more efficient than the stillborn PW8000. Time will tell whether the market will reward P&W's devotion to the geared turbofan concept, or whether it is a technological blind alley for them.
The news about planetary reduction gearboxes in aircraft engines is not new. The old man once told me about looking for photographs of busted planets that he could use in a report after yet another reduction gear failure at Wright Aeronautical in the 1940s. He said they had a broken gearset for any occasion. I am sure that any of the engineers and technicians at Garrett that sweated bullets making the TFE731 a going proposition could have told the folks in East Hartford as much.