Rolls-Royce unveils turboshaft derivative of its RR500 engine
One of Heli-Expo’09’s worst-kept secrets, the Rolls-Royce RR500 turboshaft engine, was unveiled Monday afternoon in a brief but hearing-impairment-inducing ceremony at the engine maker’s booth. The RR500 turboshaft, a 475-shp derivative of the RR300 that powers the in-development Robinson R66, is scheduled for certification in late 2011. A turboprop version of the RR500 was first announced last summer at EAA AirVenture in Oshkosh, Wis. Turboshaft RR500 deliveries are pegged to begin in the first quarter of 2012.
Concurrently, Rolls-Royce announced signing a memorandum of understanding (MOU) with Polish airframer PZL-Swidnik to discuss future applications of the new RR500 engine family. While it has not identified specific mounts for the RR500 turboshaft, a company spokesperson said, “A whole range of OEMs” are in discussion regarding RR500 applications with announcements likely “soon.”
Ken Roberts, Rolls-Royce’s president for helicopters, told HAI Convention News, “Basically, we took the 300-shp RR300 and increased the airflow.” Design engineers enlarged the compressor and modified the turbine and other components. “We wanted to keep the operating temperature relatively modest,” Roberts said to explain why engineers chose to increase the airflow. Increasing temperatures would have been another way to increase power but would have also increased the output of NOX.
The RR500 will have an electronic engine monitoring system, like the RR300, and retains the RR300’s lightweight and cost-effective hydropneumatic engine control system. It will also benefit from similarly extended maintenance intervals. While the older Model 250 has TBOs of 1,750 and 3,500 hours for minor and full shop visits, respectively, the RR500 will boast 2,000-hour and 4,000-hour intervals.
The engine is slightly more powerful than the Model 250 Series 2 (the family ranging from 420 to 475 shp). “It is targeted at new applications,” Roberts said. He suggested that some existing Model 250 applications may move to the RR500 as well.
“We run the two programs [Model 250 and RR500] in a very integrated fashion,” he explained.
The RR300 is clearly a derivative of the Model 250, and in fact, certified as such on the RR250’s type certificate, but the compressor used in the RR300 and the RR500 turboprop and turboshaft is a cleansheet design. It has a lower parts count to support high-volume production in the small engine assembly line newly commissioned at the Indianapolis facility to optimize RR300/500 manufacturing. The RR300’s Model 250 lineage makes it easier, on the derivative RR500, to keep the same engine mounts. This, in turn, makes the RR500 retrofitable
on Model 250-powered helicopters.
–Harry Weisberger also contributed to this article.