Later this month Pratt & Whitney Canada will receive Transport Canada certification for its PW150A turboprop. Flat-rated at 3,780kW (5,070shp) for take-off on Bombardier's de Havilland Dash 8Q Series 400, the engine has virtually double the power of any other member of the PW100 family from which it is derived.

To P&WC, the development of the PW150 not only represents the latest in a long line of successful engines, but also underlines the company's continued commitment to turboprops at a time when much industry focus is directed at new regional jet engines. Despite the apparent rush to jets, P&WC sees plenty of demand for regional turboprops. This will be both in traditional markets where turboprops will co-exist with jets, as well as in new markets in developing countries such as China and India. In addition, the big turboprop could provide the company with a handy re-engineing candidate for hundreds of Lockheed C-130s and P-3s.

"There are a lot of opportunities out there," says Jackie Khougaz, P&WC senior marketing account manager for regional airlines. "You are seeing new aircraft being introduced into the market and creating their own routes, and we don't see that going away," she adds. ATR, for example, forecasts sustained production of up to 40 PW127-powered ATR 42s and 72s a year. Even the 50-seat area, in which the turboprop is under attack from the Embraer RJ-145 and Bombardier's Canadair Regional Jet, ATR sees potential sales of up to 200 46-seat ATR 42-500s. Similarly, despite sluggish sales of the larger short haul regionals - of which the Dash 8-400 is the latest - Bombardier remains buoyant.

For now, the PW150 programme is aimed squarely at meeting the Series 400 entry into service target date of early 1999. The fast paced, 36-month-long effort entered the development and certification phase in June 1996 with the first run of the PW150. This was just nine months after the start of detail design and, since then, "-it has gone very successfully with around 3,500 test hours run, and all major tests have now been completed", says Khougaz.

Certification is expected to be roughly concurrent with deliveries of the first production engines to de Havilland's Downsview production line in Ontario later this month. Nine flight test engines have been delivered to date: four shipsets for the Series 400 test fleet, as well as a spare.

At the core of the engine, literally, is a new three stage low pressure (LP) axial compressor and a single stage high pressure (HP) centrifugal compressor. Each is driven independently by single stage LP and HP turbines using advanced single crystal blade materials and cooling technology derived from its larger P&W turbofan brethren. As a result of its increased size, mass flow through the engine is 75% higher than for current PW100 family members.


The PW150 also incorporates a new generation combustor and fuel nozzle design, aimed at reducing emissions, increasing life on wing and cutting maintenance costs. The incorporation of a Hamilton Standard full authority digital engine control (FADEC) system is also expected to make the engine more user friendly, as well as making maintenance easier.

The powerplant is also built with an all-helical geartrain, which cuts vibration and noise. The reduction gearbox, which P&WC claims has the lowest design stress levels in the PW100 family, drives the six-bladed Dowty propeller at around 1,020RPM for take-off, compared to 1,200rpm for other members of the family. At cruise conditions this is reduced to around 850rpm, further lowering noise. "This is of big importance because, together with aircraft active noise control and the high [350kt (650km/h)] cruise speed, it is a big selling point [for the Dash 8-400]," Khougaz adds

The FADEC is integrated with an engine monitoring system (EMS), which provides another fundamental building block in P&WC's approach to PW150 design. "We took all the lessons learned from the PW100 family and had a lot of airline advisory meetings early on," says Khougaz. "These covered things like the design and position of the externals, which, for example, are very simple, with quick removal times. There is also easy access to the LRUs [line replaceable units]" she adds.

Some of these advances were made possible because, unlike in previous programmes, P&WC has also conducted integration tests of the PW150 together with the Dash 8 nacelle and propeller. "We have therefore tested everything very extensively in the rig, ranging from nacelle ventilation and cooling to integrating the propeller electronic control with the FADEC," Khougaz adds.

Thanks to the EMS, there will be no need to guess which LRU is at fault, says Khougaz. "The EMS eases the workload of the maintenance crews by constantly monitoring engine health. Through the FADEC it measures all the major parameters and makes trace recordings of events," she adds.

Special ground-based software has been developed to manipulate the data. Through the use of the EMS, the company also believes that airlines will be able to keep a closer watch on maintenance costs. P&WC also offers fleet management plans which provide maintenance cost guarantees which are tailored to the needs of individual operators.

As with many aspects of the PW150, P&WC hopes that the design will bring the benefits of big-airline-style operations to the regional market.

Source: Flight International