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EDITOR FROM THE EDITOR M A Y 2 0 1 4 | 5 ombardier's Learjet 85 business jet few for the frst time on April 9 in Wichita, Kan. An aircraft's frst fight is a signifcant milestone, and good cause for cel- ebration. However, the Learjet 85's frst foray into the air is, potentially, even more signifcant for the aerospace industry, and might be offering us, at least symbolically, a glimpse into the future of resin, fber and process use in composite aero- structure manufacturing. The Learjet 85's signifcance does not lie in its composites-intensity. Almost every aircraft under development today — in commercial, business and general aviation — will fy composites in some way, and many will make extensive use of carbon fber composites in the fuselage, wings, tail and other structures. What sets the Learjet 85 apart is how and with what Bombardier is manufacturing the plane's composite structures. Pierre Harter, engineering manager – M&P;, tech- nology readiness and structural certifcation Lear- jet, reported at SAMPE Tech in Wichita late last B tions more challenging. On top of that, Harter says breathing methods, debulk cycles, dwell times and resin rheology need- ed special tweaking to achieve less than 1 percent void con- tent in fuselage parts. When asked why Bombar- dier is taking the time, and go- ing to the expense and effort required to develop an OOA process for the Learjet 85, Har- ter said the company saw that aerostructures manufacturing was headed in this direction and wanted to be in front of the technol- ogy, not chasing it … or competitors. Even more time, expense and effort, of course, was required to meet the most important chal- lenge: the U.S. Federal Aviation Admin. (FAA). As Boeing and Airbus did with the 787 and A350 XWB respectively, Bombardier was required to perform extra tests to meet the FAA's special conditions for certifcation. These focus on infight fammability, post-crash fammability, crashworthi- ness, durability, toxicity in burn, dam- age tolerance and thermal expansion at interactions with metals. The more composites are used in aircraft, the more familiar and comfortable the FAA will become with what is still, in its view, a relatively novel ma- terial. Thus, theoretically, composite aircraft certi- fcation will become easier and faster. Until then, however, airframers like Bombardier will bear the brunt of the extra scrutiny on behalf of what should be a grateful industry and will surely earn a place among composites industry pioneers. Less certain, however, is the Learjet 85's place in the evolution of composite materials and process development. Does it mark the frst large step out of the auto- clave, or will it be an historical anomaly? I would wager the former, and I look forward to what the aerocomposites industry does next. jeff@compositesworld.com Jeff Sloan year that the wingskins and spars for the plane are manufactured in Belfast, Ireland, using an in-auto- clave resin transfer infusion (RTI) process. More- over, the fuselage and empennage are manufac- tured in Querétaro, Mexico, via an out-of-autoclave (OOA) vacuum-bagged process. Infusion and OOA are not new, but their use in the manufacture of major aerostructures was, prior to the Learjet 85 program, largely unexplored terri- tory. The production of the fuselage is particularly ambitious. It's done with Cytec Aerosapce Materi- al's (Tempe, Ariz.) CYCOM 5320 prepreg, under vac- uum bag in a conventional oven — at about 6,000 ft/1,829m above sea level in south-central Mexico. The altitude, of course, makes the vacuum calcula- The more composites are used in aircraft, the more comfortable the FAA will become with what is a relatively novel material. 0514HPC EditorLetter-OK.indd 5 4/22/2014 2:48:56 PM