Pratt & Whitney confirms the first flight test of the PW1200G geared turbofan for Mitsubishi’s Regional Jet (MRJ) on the company’s Boeing 747SP flying testbed is scheduled within the next two weeks.

The PW1200G will be the third version of the GTF to fly following initial flights of the proof-of-concept PW6000-based demonstrator in 2008 and, more recently, the initial production PW1500G variant for Bombardier’s CSeries. Pratt also confirms that the PW1500G completed its second flight test campaign last month, logging 130 flight hours and 26 flights.

The first MRJ engine to fly, PW1200G test unit 404, is the smallest member of the PW1000G GTF family and also the first to fly on the company’s second 747SP. Unlike its higher-powered siblings, the MRJ engine has a smaller 56-in.-diameter fan and a thrust rating range of 15,000-17,000 lb.

Because of these changes, Pratt is testing the engine on a specially designed side strut adaptor mounted to the fuselage of the 747SP, rather than placing it under the wing in the No. 2 inboard position, as on the first testbed.

The MRJ engine was transferred to Pratt’s Mirabel, Quebec, site for the start of flight tests following the completion of sea level testing in Florida in February.

The second PW1500G flight test effort for the CSeries program explored engine handling, restart capability and modifications to improve the efficiency of the compressor and fan. The changes were concerned with clearance management, thermal growth and tighter clearances, as well as slight changes to the aerodynamic profile of the production standard fan blade, says Pratt.

Tests were conducted at altitudes up to 41,000 ft. and also included fan stress certification. Bob Saia, VP-next generation product family, says, “We also subjected the propulsion system to substantial flight maneuvers, including negative g testing, which validated system capability.”

A third flight test phase in “late summer” will fly the CSeries engine with the full-up production nacelle and validate the final electronic control logic.

“This will manage the compressor as well as the variable area nozzle,” says Saia.