As with any perennial best-seller, P&WC now faces the inevitable and challenging issue of where to go next. Having essentially created its own market with the PT6, the engine maker knows it cannot sit still while the competition grows stronger (see page 48). The tempting “if it ain't broke, don't fix it” approach is not an option, and yet P&WC must carefully weigh the pros and cons of too much technology development versus too little as it plots the next move for the jewel in its family crown.
The first questions P&WC engineers have been asking are, “Has the company fundamentally exhausted the baseline PT6 of any further potential improvements? Or is it now a case of diminishing returns for the investment any such upgrade path would incur?” Absolutely 'no' to both, says Saabas.
“Incremental improvements will continue, starting with electronic controls. This improves the interface with modern cockpits,” he says.
However, recognizing that part of P&WC's conundrum with the PT6 succession strategy is meeting the needs across the very breadth of the market it helped develop and serve, Saabas is realistic about the need for a tactical approach. “People want different things. Not everyone wants dual-channel digital control. With the PT6, it is not a case of one size fits all. We're also looking at areas like a time-between-overhaul (TBO) life extension through the use of advanced materials and technologically improved combustion for less distortion.”
“One of the key messages is that we are still investing heavily in technology on the PT6,” says General Aviation Products Vice President Denis Parisien. “For example, for the PT6 A-140 just certified for the Caravan, we've injected technology, increased the size of the compressor and put technology in the hot end and improved specific fuel consumption (sfc) by up to 7%. So our intent is to carry on continuously improving the performance of the engine and make it in as wide as a variety of versions as we get close to 2,000 shp. Our next challenge is do we bring it above 2,000 shp? It's in our technology plan to see.”
Parisien asserts that “we can't stop injecting new technology,” and he highlights the parallel focus on reducing pilot workload and improving overall engine performance. The approach has been taken in the past, such as when P&WC continued to improve the JT15D while concurrently introducing its effective replacement, the PW500 turbofan. “We have a tradition to lead the next technology step,” he says. “That's why we have a big research and development effort underway, so when the market requirement is there, the technology is available.” From the fuel-burn-reduction perspective, “the approach is to look at how far we can push it with technology,” Parisien adds.
When it comes to achieving step-changes in performance—particularly in areas like fuel consumption—manufacturers have often resorted to wholesale changes in architecture to meet the ambitious targets expected of the next generation. But doing so could impact the fundamental simplicity (and therefore reliability) of the PT6's hallmark design. So this factor is being taken into consideration when it comes to next steps, says General Aviation general manager Nick Kanellias.
“The thing I hear most about is the reliability of the PT6. Reliability is the biggest factor and it is where we differentiate ourselves. That's where the people who designed the PT6 really got it right. The reason it has gone from 500 shp to 2,000 shp is because of the modular design. It just made it easier for us to offer a variety of options, as well as characteristic advantages such as reverse flow and foreign object damage (FOD) prevention,” he adds.
A related consideration is avoiding the temptation to make a new, or upgraded, PT6 too sophisticated. “We can't take the risk of taking away anything the customers rely on,” says Kanellias “It is paramount that any technology has to be consistent with what people have come to know. It also has to be something the customer can afford.” The same limitations would apply to whether any future PT6 upgrades could be offered for potential retrofit, he says.