THE CATALYST ENGINE

Beechcraft and Cessna have a long history building successful turboprops planes, but for the Denali they decided they needed an all-new engine – and that’s been their big problem.

The new Catalyst engine builds on GEs acquisition of Czech engine maker Walter. In 2008, GE Aviation acquired Walter Engines, the builder of the very successful and widely used M601 turboprop series. But by 2008 Walter had seen better days. Of the 37,000 M601s delivered since 1975, only about 1,500 were still flying. Although the company continued to overhaul M601s it delivered fewer than ten new engines each year from its World War II-vintage factory in Prague.

With the 2008 sale of Walter to General Electric, GE built a new factory and introduced an improved M601 derivative, called the H Series, using the latest GE big jet technology. The H Series, with three variants ranging from 750 hp to 850 hp, incorporated new advanced material and a blisk design in the compressor that significantly improved fuel burn, power and durability. The H Series turboprop was well accepted by the market as original equipment for new aircraft such as the Thrush 510G, Let 410 NG and the Nextant G90XT.

Despite its success with the Walter derived engines, GE faced a whole new set of challenges with the larger Catalyst which could have made the project too much for any company smaller than the massive GE. Reassuringly though for the Beech Denali, AW&ST guru William Garvey reckons that, “There is little doubt that the 1,300-shp engine—which promises excellent fuel burn, power output, weight reduction, time between overhauls (TBO), decreased complexity and features a full-authority digital engine control— will earn its certification.”

Work on the Catalyst began in 2016 and the result has been an engine with 800 fewer parts than traditional turboprops, partly thanks to 3D printing. GE still hopes to have the Catalyst certified before the end of 2021. A bi-lateral agreement with European authorities means the FAA and EASA will recognize each region’s certification of the engine.

Progress has been frustratingly slow. GE finally delivered a ‘flightworthy’ engine to Beechcraft in December 2020. It had been hoped to begin flights in Berlin in early 2021 using a King Air 350 whose left-wing Pratt & Whitney PT-6 had been replaced with a Catalyst. But the first flight is yet to happen although GE says it “will be coming soon.”

The Catalyst borrows many technologies from GE’s big engine business to create a full-authority digital engine control (FADEC) turboprop that—if it lives up to expectations—is certain to give Pratt & Whitney’s venerable PT6 a run for its money.