Learjet 85 has deep European roots

 - May 16, 2011, 8:30 PM

Bombardier’s all-composite Learjet 85 is progressing toward a first flight in 2012 with heavy engineering and manufacturing input from the company’s facilities at Belfast in Northern Ireland and Manchester in the northwest of England. Early this year, program director Ralph Acs reported that 80 percent of the detailed design drawings had been released for structure and systems installation with the goal of completing them this spring. According to manufacturer, the eight-passenger, 3,000-nm-range aircraft remains on schedule for certification in 2013.

“In Manchester, we pulled [an engineering team] together from the European Community,” explained Acs. It consists of 120 engineers making ply-by-ply drawings that can be sent electronically directly to Bombardier’s composite factory in Mexico.

The $17.2 million Learjet 85 is being brought to market by a global team, using Bombardier’s engineering and manufacturing assets in Canada, Europe, Mexico and the U.S. The Belfast facility will make planks, spars and other parts using resin transfer infusion technology (RTI), the same composite technology tapped for Bombardier’s new single-aisle C Series airliner.

Acs said the use of composites on the Learjet 85 will significantly decrease final assembly time because the parts are larger and because of the very design of the parts. For example, the fuselage barrel, from bulkhead to bulkhead, is one part number. Structures such as stringers are integral parts of the composite mold, cutting down the need for fasteners and drilling.

The Belfast facility will perform destructive test article validation prior to the start of large-scale fabrication. The first set of spars are now being packaged for shipment to Bombardier’s Queretaro, Mexico plant, which will fabricate the wings and the fuselage before they are trucked to Wichita in the U.S. for final aircraft assembly. Belfast also is preparing for composite plank manufacture. “We’re getting organized for the tooling,” Acs said. “Tooling for the planks is significant.”

Last year Bombardier completed an 185,000-sq-ft expansion of the Queretaro complex, bringing total space dedicated the Learjet 85 program there to 221,300 sq ft. More than 1,200 employees in Queretaro work on a variety of programs including the Learjet 85, the Q400 turboprop, the CRJ series and the Challenger 605/850. Throughout Bombardier, approximately 1,250 employees are dedicated to the Learjet 85 program.

Technology Readiness

Acs said the company’s extensive experience building composite components for existing aircraft would enable it to better make the transition to an all-composite aircraft such as the Learjet 85. He further noted the role of the company’s six-phase “technology readiness program” in keeping things on track. The program covers material selection, process optimization and repairability of components. Effective management of the supply chain will also be critical to the program, he said. There are 41 major companies supplying the Learjet 85 and Acs said he uses a variety of methods to keep the program rolling on time, including peer pressure and pre-testing components before they are installed in the aircraft.

“We meet with our suppliers every six months and last September we brought them down to Mexico. There they got up and gave a ‘show-and-tell’ on how well they were doing­­–so there is a lot of peer pressure,” Acs said.

Installing components in test rigs is another tool Acs and his team use to keep on schedule. “One of the big keys to success is to exercise the systems before they arrive at the final [assembly] line. Electrical, powerplant, all of this has to be exercised to drive and improve reliability. Entry-into-service reliability at the first flight is the strategy, and around the world we have 63 rigs to commission to support what we are doing. For example, we have an integrated rig at Rockwell Collins and any LRU [line replaceable unit] that interfaces with that avionics suite has to visit Rockwell Collins and go through integration checks twice. So when that avionics suite [Rockwell Collins’ Pro Line Fusion] shows up on our aircraft, I can say the ‘boxes’ have shown they have talked to each other.”

Dealing with Weight

Early production all-composite aircraft traditionally have had overweight issues, and Acs said Bombardier is attacking this through a combination of material and process selection. “We have had very good [weight] correlation with destructive test articles because we weigh them and they correlate within a couple of pounds of the drawing,” he explained. “This level of accuracy has a lot to do with the process. Composite plys are pre-impregnated with resin so that variable is controlled. The next step is to make sure we are cutting [the plys] to the exact size. The actual manufacturing process from the design is quite repeatable” thanks to the extensive use of computer technology, he said. 

In Manchester, Bombardier’s engineers draw parts ply-by-ply in a computer program called Cybersim. The Cybersim drawings are then sent to the Mexico factory where they are uploaded to a system that projects a series of green boxes onto each composite mold, ply-by-ply and layer-by-layer, helping to ensure precise ply placement and weight control.

The rigidity of composite fuselages can present challenges for cabin noise control that require lateral thinking. Conventional metal aircraft can use noise-dampening blankets wedged between fuselage spars and frames. However, the Learjet 85’s fuselage is a single composite section approximately one-inch thick without these structures. While not divulging details, Acs said Bombardier already has done acoustic testing on the Learjet 85’s composite panels at European laboratories, while also working to formulate passive technology solutions for the fuselage.

Inside the cabin, Bombardier has tapped Lufthansa Technik to provide the cabin management system, but Acs said systems specifics would not be finalized until late into the flight-test program due to the rapid pace of technological change. “We want to make sure the CMS backbone is adaptable. You have to cater to the traditional customer who is familiar with none of that stuff [iPADS and so forth] and just want to use what is on the airplane, but you also have to satisfy the whiz who shows up with the latest toys,” he said. One aspect of the CMS architecture being studied is a combination monitor/touchscreen.

Five test aircraft and two structural test articles are scheduled to be used in the certification program. The fourth aircraft will fly with a production interior. While not revealing exact order numbers, Acs said he expects it to be popular with European customers because of its range. “It can get you to Moscow and the Middle East and you can use 5,000-foot runways,” he concluded.