Thrush 510G Ag Aircraft Makes 1st Flight

An upgraded Thrush 510G agricultural aircraft powered by the General Electric-developed M601-H80 turboprop made its first flight from the airframe maker’s Albany, Georgia site on Nov 23.

The flight marks a key milestone for GE’s efforts to develop the former Walter M601 derivative into a viable alternative to Pratt & Whitney Canada’s ubiqitous PT6, as well as the start of Thrush’s certification campaign. The aircraft is scheduled to make its public debut at the U.S. National Agricultural Aircraft Association (NAAA) event in Savannah, Georgia on Dec 6.

The Thrush 510G is the first new turboprop engine application for GE, which acquired Prague, Czech-based Walter in 2008 specifically to penetrate the general aviation market with a new line of competitive engines. The turboprop combines the basic features of the Walter-designed M601 with GE-developed three-dimensional aerodynamic blade and vane design, as well as more advanced materials.

The H80 began its certification program on March 8 with a first run in the recently relocated GE Aviation Czech facility in the Prague suburb of Letňany. “The M601 provided the first opportunity,” says Brad Mottier, Vice President and General Manager of GE Aviation’s Business and General Aviation Operation. Improvements to the compressor and gas generator/turbine have enabled output to grow from 840 shp to 1,070 shp. “That’s not even including potential improvements to the power turbine and gearbox, so we have plans to enhance those beyond the H80.” Initial targets with the more powerful variant include the King Air 200, he adds.

Although a baseline version of the M601 flew in a proof-of-concept flight test Thrush in 2009, the late November flight in the 510G was the first for a production-compliant H80 in the upgraded airframe. Thrush, which reduced the weight of the crop duster by 270 lb, will offer greater payload capability in the 510G compared to earlier models even though the H80 will be de-rated to around 800 shp.

Originally due to be certificated in mid-2010, the development was held up while engineers worked to reduce idle speed. Although developing around 50 shp more power than the original PT6A-34AG, Mottier says the GE engine will have additional temperature margin and a slower propeller running at 2,080 rpm against the original 2,200 rpm. Having missed the initial mid-year certification target, Mottier says “we had hoped to get it done in the fourth quarter of 2010. But we wanted it to idle slower and it took some time to do that.”

European EASA and U.S. FAA certification is now targeted for the first quarter 2011. “But we’re working hard to accelerate and pull that in because Thrush wants to hit the North American season. We’re under a time crunch to do that, but we think we’ll basically meet it,” Mottier adds.

Unlike the PT6, the H80 has no fuel nozzles and instead employs a ‘slinger’ fuel-feed to the combustor similar to the Williams FJ44. Without the risk of coking and zonal heating, there is therefore no hot section inspection required. GE says the H80 will also feature an extended service life of 3,600 flight-hours and 6,600 cycles between overhauls, as well as enhanced hot-day takeoff performance and high-altitude cruise speeds. The H80 will also come with the option of a single or dual acting propeller governor.