Pratt & Whitney Canada treats its PW600 series with the levels of secrecy normally reserved for a military engine than a family of small turbofan for business aircraft. Although P&WC acknowledges information will ultimately spill out, "we're trying to guard some of those details for as long as we can," says turbofan development vice president Dan Breitman.
P&WC believes its early decision, in 2000, to develop the simple PW625F demonstrator and grab the initiative in the emerging very light jet market was vital. Just as crucial, the company believes, is maintaining its competitive advantage by staying quiet on some design aspects - such as overall pressure, bypass and compressor ratios and operating cycles. "It's been one of our overriding successes, and we can never be asleep at the wheel particularly with these emerging markets when they could erupt into huge volumes. We've been a believer in this for four to five years, long before most other engine makers caught wind of it," says Breitman.
Based on the architecture of the PW625F demonstrator, which ran in 2001, the Mustang's PW615F is the first of the new-generation light jet powerplant family to be certificated, and was the benchmark for the next two family members to be launched the PW610F for the Eclipse 500 and PW617F for the Embraer Phenom 100.
Rated at 1,350lb thrust (6kN), the PW615F has a 40.6cm (16in) diameter, solid titanium, wide-chord fan and a two-stage axial-centrifugal high-pressure (HP) compressor, believed to be made up of a mixed half-axial/half-centrifugal stage and one centrifugal stage. The engine includes single HP and low-pressure (LP) turbine stages, a reverse flow combustor and forced mixer/common exhaust. Control is provided by a dual-channel, full-authority Hispano-Suiza Canada-developed electronic engine control system.
The engine has around 40% fewer parts than previous powerplants in a similar thrust class, such as P&WC's PW500, and is made up of just 13 interchangeable modules. "One of the things we were concerned with when we started to look at this potential market was you could eventually have people out there working on these engines in their own garages. So we designed it to be simple, rugged and robust," says Breitman.
The result is an engine that is not only easy to mass produce, but easy to inspect, overhaul and maintain. A hot section inspection, for example, is achievable on-wing within eight hours and engine accessories are "one deep" - they are accessible without requiring removal of other parts.
P&WC plans to build one PW600 every 8h. "We're not Henry Ford and the Model T exactly, but when we started this we had to look at the potential volumes and how we'd design it for that," says Breitman. "But it's not something you can do after the fact. You can't just take an engine and start re-designing parts for both easy assembly and maintenance. You have to get a balance between the two, and we've done that thanks to some pretty innovative design features." Although Breitman remains coy over details, he says: "We did look at the fabric of the casing in a way that takes it beyond its traditional structural duties and gives it more responsibility."
Final assembly is gearing up in Montreal, and 40 production-standard engines have been delivered to Cessna and Eclipse. Test time is also being built up on development engines, including additional flight time on the company's Boeing 720B testbed. "We have around 20,000h on our endurance engines across the 600 family. That's a high number for a new programme for us, but with the volumes on this you can't afford to have a problem," says Breitman.
Source: Flight International
