Integrated Modular Avionics: Less is More

By James W. Ramsey | February 1, 2007
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The Integrated Modular Avionics (IMA) concept, which replaces numerous separate processors and line replaceable units (LRU) with fewer, more centralized processing units, is promising significant weight reduction and maintenance savings in the new generation of commercial airliners.

Boeing said by using the IMA approach it was able to shave 2,000 pounds off the avionics suite of the new 787 Dreamliner, due to fly in August, versus previous comparable aircraft. Airbus said its IMA approach cuts in half the part numbers of processor units for the new A380 avionics suite.

"It’s not just the IMA modules themselves, and reducing the number of LRUs. IMA brings a more efficient network for the aircraft," said Bryan Vester, vice president of commercial systems strategy development for Rockwell Collins, a supplier to both Boeing and Airbus. "From an airline standpoint, fewer types and varieties of spares should drive higher reliability, and therefore less maintenance."

Some believe the IMA concept originated in the United States with the new F-22 and F-35 fighters and then migrated to the commercial jetliner arena. Others say the modular avionics concept, with less integration, has been used in business jets and regional airliners since the late 1980s or early 90s. The concept also is seen on the military side in the KC-135 and C-130 upgrades, as well as in the new Airbus A400M transport.

But regardless of where it began, IMA is the trend of the future due to the economies in fuel savings derived from less weight and lower maintenance costs. It also offers an open architecture allowing for the use of common software, which makes upgrades and changes both cheaper and easier to accomplish.

"An IMA operator can upgrade software without having to upgrade the hardware, and vice versa," said Jean Pierre Gillet, Airbus senior director of IMA support and services.

Using elements common to different computer modules makes maintenance of the computer less expensive. Since the same part (or card) can be used in any of the IMA computers, inventory in the shop is smaller. The advantage is less expensive maintenance, Gillet said.

While adapting the general concept of "shared resources," the Boeing 787 and the Airbus A380 approaches to IMA differ. Both aircraft have applications for specific LRUs that are on the plane and individual computers for certain systems.

Key to the B787 avionics suite, which Boeing developed with partners Smiths Aerospace, Rockwell Collins and Honeywell, is a central computing system Boeing calls the Common Core System (CCS), which eliminated more than 100 different LRUs.

‘Open IMA’

The A380 Super Jumbo, which touts 15 to 20 percent lower operating costs than previous airliners, applies the IMA concept with computers capable of hosting different functions and integrated modular avionics connected by a network. This approach differs from Boeing’s 787 central computing system in that it does not rely on a single (or dual) central processor to run most of the aircraft systems.

Instead, the A380’s IMA approach relies on eight processing modules, some tailored for specific applications, but all tied together by a common Avionics Full-Duplex Switched Ethernet (AFDX), ARINC 664 standard network. Seven of the 3-MCU computers are core processing input/output modules (CPIOM); the eighth is an input/output module (IOM).

"Even if all these computers are connected to the AFDX, and the majority of the communications is done through the network, there is some specificity on the module depending on which function they are in," Gillet said. "There is a slight difference in the input/output of the computers, which is why they have different part numbers."

Although the Airbus IMA computers have eight different part numbers, memory and power supply cards are common to all the computers. It is only the input/output card that is different, depending on what type of system the computer interfaces with.

Gillet emphasized that the use of a central processing system "is not exactly the way we have followed on the A380. There are seven CPIOMs doing different types of functions. We have preferred to develop what we call an open IMA — some computing resources on which we can have different functions hosted."

Rockwell Collins is providing the AFDX network for the A380 along with overall network integration support to Airbus and to third-party suppliers that have network "end systems" embedded into products they are delivering for the A380, Vester said. The end system, a chip set, is required in a manufacturer’s box in order to have a network connection.

Gillet described the three functional domains of IMA as: cockpit (electrical flight control, communications and warning); cabin (air conditioning and pneumatics); and utilities, including energy, fuel functions and landing gear functions.

There are 30 line replaceable modules, all 3-MCU boxes, associated with the IMA platform, and 22 software functions hosted in the CPIOMs. France’s Thales and Airbus Avionique each are providing CPIOMs.

Some 11 suppliers provide software functions hosted within the IMA, ranging from communications to landing gear extension and retraction. They include Fairchild Controls (pneumatic), Parker Aerospace (fuel applications) and Hamilton Sundstrand (air conditioning).

Rockwell Collins’ role on the A380 differs from the role it has on the Boeing 787, where it acts as network integrator for the latter’s Common Data Network. Rockwell Collins contracts directly with Airbus to provide the network on the A380, and Airbus is integrating the computing part of IMA with the network, said Joel Otto, Rockwell Collins’ program manager for Boeing programs.

For the A380, Rockwell Collins provides data link applications software — a "router" for airline operational control (AOC) functions — hosted on the IMA platform and used for communications between the aircraft and the airline’s network operations center.

"The AOC function is hosted on the IMA, but like in any ACARS (Aircraft Communications Addressing and Reporting System), we can tailor it for the airline’s specific application," Vester said.

Suppliers also are providing systems not hosted on the IMA. Honeywell is providing the A380’s flight management software, which has its own computer, and Airborne Environment Surveillance System, combining the company’s RDR-4000 weather radar, transponder, Traffic Alert Collision Avoidance System (TCAS) and Enhanced Ground Proximity Warning System. The system represents a 50 percent volume and 40 percent weight reduction from previous federated surveillance equipment, said Robert Majure, platform systems product management director for Honeywell.

Through its IMA Support and Services group, Airbus is "providing to the customer supplier-type support for the integrated platform," said Gillet, who heads the organization. "Like a supplier provides training on classical LRUs, we provide training that includes hardware as well as software that is hosted by the hardware."

The support includes spares and a training program for repair technicians offering instruction in IMA familiarization, shop maintenance and engineering maintenance training.

B787 integration

In a change of philosophy, Boeing is giving its first tier suppliers more integration responsibility for system packages on the 787 Dreamliner. They provide packages that may require subcontractors, and can include more than one of their products.

Smiths provides the Common Core System, which is comprised of general processing modules and remote data concentrators that replace traditional wiring with I/O devices that concentrate analog and digital signals from the remote sensors and send them on the network to the processing modules.

A third IMA component, Rockwell Collins’ Common Data Network, is a fiberoptic Ethernet connecting all systems that need to communicate with the CCS. It consists of external switches using ARINC 664 standard protocol.

The processors use an ARINC 653-compliant operating system supplied by Wind River Systems, Alameda, Calif.

"We design the hardware, using their operating system, and then we layer other software services on top of it. Beneath it is a commercially available operating system," said Mike Madden, Smiths’ business director of platform computing systems.

This open architecture "allows the whole IMA approach to go forward," Madden maintained. If changes or upgrades are needed, "Boeing, or the developer of the platform, can select other suppliers to provide functions and minimize the financial impact and complexity of integrating those applications."

Smiths is delivering B787 hardware to Boeing, for use in its integration facilities, but also to suppliers Boeing selected to provide applications and functions using the IMA. The suppliers are integrating their applications onto Smiths’ hardware for delivery to Boeing.

Smiths, along with other suppliers, planned to ship components to Boeing early this year for the first B787 flight.

"We are certainly looking at taking products and technologies, the tools in particular — that we have developed on the 787 and other programs, like C-130 AMP (Avionics Modernization Program) and the Boeing 767 tanker, into next generation IMAs for a number of commercial customers as well as some military opportunities," Madden said.

Rockwell Collins is supplying the B787 communications system and Configurable Integrated Surveillance System (CISS). CISS combines the company’s MultiScan automatic weather hazard detection system, Mode S transponders, TCAS and Terrain Awareness Warning System into a single system, which Rockwell Collins points out, uses 40 percent fewer parts than traditional federated aircraft systems.

Rockwell Collins also is supplying the B787 cockpit display system, which includes its dual head-up displays as standard equipment. The company is providing the core network cabinet, a platform that provides for both cabin and flight deck applications and manages onboard information flow to improve airline operations efficiency.

As supplier of the B787 pilot controls, Rockwell Collins delivered the first fully operational system to Boeing to develop an integrated test vehicle. The pilot controls include interfaces to the aircraft’s fly-by-wire flight control system.

At this writing, Rockwell Collins had completed initial deliveries of pre-certification hardware to Boeing for its integration facilities, and began deliveries for the first B787 flight test aircraft.

A large amount of avionics integration work has been accomplished at the Rockwell Collins lab in Cedar Rapids, Iowa, including integrating functions from other suppliers.

Honeywell provides the flight management system software that resides on the B787’s IMA system as part of its navigation component, which also includes its air data inertial reference unit and multimode GPS receiver.

The Honeywell crew information/maintenance system evolved from the central maintenance computing and aircraft condition monitoring functions the company developed for the Boeing 777.

"Boeing’s 777 AIMS (Aircraft Information Management System), from my point of view, was the first actual IMA implementation, in commercial aviation," Majure said.

"The IMA concept is all about weight and power savings. With new aircraft getting more software-based functionalities, and computers becoming more powerful, it doesn’t make sense to add another box with its own computer every time you want to add a new feature or function. It makes a lot of sense to share computing resources."

Honeywell also provides the flight control package for the B787’s fly-by-wire system. The company was in systems level integration, and deliveries had begun to support the first flight.

A380 Awarded Type Certificates

FAA and the European Aviation Safety Agency (EASA) late last year issued type certificates for the Airbus A380, the first concurrent certification by the two agencies.

"This is the first major leap in aircraft capacity in over 35 years," FAA Administrator Marion C. Blakey said at the hand over ceremony Dec. 12 in Toulouse, France. "… All of aviation, on an international scale, stepped up to the plate to ensure that we were ready to deal with the size of this airplane, especially in terms of airports and airspace. Frankly, we’d never had to deal with something this big."

Airbus applied to FAA for certification of the A380 in August 1998. The French certification process began the same year and was taken over by EASA when the latter agency started operations in 2003. The size and complexity of the aircraft required FAA to extend its normal five-year certification period for a large airliner to seven years.

Troubled by delays, the A380 program suffered a blow last November when FedEx Express canceled its order for 10 A380-800F freighter versions, replacing it with an order for 15 Boeing 777 freighters. The first, 555-seat passenger version is slated to be delivered to Singapore Airlines in October.

With a takeoff weight of 1.2 million pounds, the A380 is the largest and heaviest commercial airplane ever built.

FAA said flight tests to approve A380 operations on 150-foot-wide runways were expected to be completed in the second quarter.

Meanwhile, the International Civil Aviation Organization was considering minimum separation criteria for airplanes operating behind an A380 in all phases of flight to minimize wake vortex effects.

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