Bell Helicopter is preparing to start assembling the first prototype of the 525 Relentless super-medium twin later this year at its facility in Amarillo, Texas. Four more prototypes are expected to join the test program before certification in 2015. Bell and its suppliers have begun manufacturing parts for the helicopter, which was announced in February last year and is slated to fly for the first time next year.
The 525 is an 18,000-pound “plus” helicopter with an expected range of more than 400 nm, a cruise speed approaching 150 knots, a ceiling of 20,000 feet and seating for 16 to 18 passengers. It will be powered by a pair of GE CT7-2F1s (1,800 shp each) driving an all-composite five-blade main rotor system and a four-blade tail rotor. The aircraft will incorporate a triple-redundant fly-by-wire flight control system with a BAE flight computer that incorporates lessons learned on the Bell/Boeing V-22 Osprey military tiltrotor. The 525 will also feature a touchscreen-controlled Garmin G5000H glass panel integrated avionics suite with four main displays. (Garmin originally began developing the G5000 for the new Cessna Citation X. Both Bell and Cessna are owned by Textron.)
Bell is not taking orders for the new helicopter yet, but it expects heavy interest from the offshore oil and gas industry. The 525 mockup unveiled at Heli-Expo last year was in the livery of OGP provider PHI. However, the company, working with its customer advisory panel, has identified four more primary mission segments for the 525: corporate and VIP, helicopter emergency medical service (Hems), firefighting, and search-and-rescue/parapublic.
At certification Bell plans to have a substantial number of kits approved for various missions via STC (supplemental type certificate). Bell has identified approximately 82 kits that support each of the mission configurations. It will also offer various degrees of customization. “We didn’t just bring together the customer advisory panel to define the product in the beginning; we are using it throughout all phases of design,” said Larry Thimmesch, Bell vice president of commercial programs. “You see lots of products out there that get after-market additions to make them effective. To me that is a failure in design.”
Over the summer Bell announced additional suppliers for the 525, including GKN Aerospace and Triumph Group for airframe structure machining and composites; Kuka for major structural tooling; Goodrich for ice protection; Israel Aerospace Industries for passenger seating; and Mecaer for wheeled landing gear.
Thimmesch told AIN that Bell completed the preliminary design phase last summer. “All of the interfaces have been designed between parts. If I have the interface between two parts defined I can design the part with detailed data and less collaboration.” The 525 is being designed digitally, without paper drawings, using Dassault Systemes’ Catia v6 and Enovia software. Approximately 430 Bell employees are working on the 525, half of them engineers. “There are many new things on this program, not just in terms of product but also in terms of process and cultural change,” he said.
This includes how Bell’s first paperless aircraft is designed and built. “We are focusing on releasing our digital models. These digital product definitions (dpds) carry all the information in 3-D needed to build and manufacture the part. Everything is defined, creating a seamless data flow and saving time,” Thimmesch said. It is one reason why Bell can design the 525 and build prototypes with such a relatively small staff.
Thimmesch explained how it works. “There is one bill of material. Manufacturing engineers can put together a manufacturing and assembly process that is the engineering definition of that assembly. They are one and the same, so there is no separate synthetic set of manufacturing numbers. That translates into the work instructions on the factory floor that will show mechanics how to assemble. All the instructions are in a virtual 3-D environment from the same source of data that was used to design the component and plan [the manufacturing and assembly processes]. That same data will go out and support the technical publication manuals. There is less transaction time, less time for human intervention and error, and it is [closer to] seamless in the manufacturing and customer arena. This is the first project designing an aircraft in the digital environment with Enovia and Catia v6, software, which is new in the industry, and other major OEMs are actually watching us pilot these tools through the program to learn from the process.”
System Integration Tools
However, Bell is not relying solely on virtual data to validate its design. Like many other OEMs, it has system integration labs devoted to the new aircraft. What is different at Bell, Thimmesch said, is how early in the process labs were up and running. “We have never had one up and running this early in a program before, and this is all about our focus on learning. The sooner we can learn, the more mature the product will be, and the less change we will have later. The systems integration lab (SIL) is what I call our first prototype aircraft. It is already functional for flight controls and avionics. We are already doing testing there and by the middle of this year we will have the lab fully functional. You will sit in a cockpit and move the cyclic, and the swashplate will move in the hydraulics portion of the sim lab. It really tests out the integration, and we are actually going to use [this effort] for certification credit. It is going to be a conformed configuration and will be fully operational a year before flight-test,” he said.
Bell already has a prototype cockpit simulator, called the sim cab, up and running at its Fort Worth headquarters that it is using to mature the control laws and math models for the 525’s fly-by-wire controls. A duplicate sim cab is under construction and will be part of the SIL.
Bell is also building rigs to test access and the durability of key components such as door mechanisms. Members of the customer advisory panel used a roof access test rig late last year to validate the locations of maintenance access doors as well as built-in steps and safety harness tie-offs to the upper deck.
“Things that customers touch every day when they get into or out of an aircraft–those are the things that we want to make sure are robust, reliable and function well,” Thimmesch said. “We’ve already built a prototype for our J-track crew seat and are wringing it out. We are getting ready to build a sliding mechanism for the main cabin door to make sure it works flawlessly. We are looking at those prevalent man-machine interfaces and doing testing above and beyond what is required for certification to make sure they are mature when the helicopter gets into customers’ hands.”
Bell has already assembled the 525’s tail-rotor assembly actuator, elements of the main-rotor gearbox and the accessory gearbox. Bell suppliers have begun to fabricate parts. In October, GKN produced the first fuselage longeron. As of December, it had yet to fabricate main rotor blades. “We are on track for all our weight and schedule targets,” Thimmesch said. “All of our major tooling suppliers are on board and building tools. Everybody is getting ready for the start of production. It’s full speed ahead now.”