U.S. navy avionics systems embrace open architectures

Designers of avionics equipment for U.S. Navy aircraft see obsolescence as their biggest obstacle in meeting the steady demand for upgrades and retrofits of existing aircraft. Their main weapon in this fight is to design each system with an open architecture.

By John McHale

The commercial avionics world took a big hit with the recent economic downturn, but the military market, especially for U.S. Navy programs remains strong with old and new aircraft receiving the latest avionics systems based on open architectures to help combat component obsolescence.

"The military avionics market is strong for Honeywell Aerospace, however it will be a good year before the commercial market turns around," says Greg Walker, Manager, Military Crew Interface Systems, Honeywell Aerospace in Phoenix. For new programs of record the funding is fairly secure, but the real meat of the business will come from retrofitting and upgrading existing platforms in commercial and military sectors, he adds.

This also means more obsolescence issues as the program development life for most military flight systems is measured in years, where commercial-off-the-shelf (COTS) technology goes obsolete in as little as 18 months, Walker says.

"The F-22 is shutting down and the Air Force has no new birds forcing the military" to keep older aircraft flying even longer, Walker says.


F-35 Joint Strike Fighter leverages COTS for avionics systems


Managing obsolescence in military systems

"Obsolescence management kills us," he continues. Everybody in the military community faces this issue because if a device goes obsolete we generate the volume to keep it alive" with the vendor, he adds.

On the avionics side the way to go is with an open systems architecture to more easily swap out parts that are no longer being made, Walker says.

One method to combat obsolescence is by making a lifetime buy of a component when a vendor announces that they making it obsolete, Walker says.

One problem with this method is that military development cycles last anywhere from four to seven years and by the time the system is ready for deployment the components are no longer effective and the end user may be forced to do a costly redesign of the avionics system, he explains.

"We have two 2 major processor card lines, one for general purpose processing and one for dedicated display graphics generation," Walker says. "Each is upgraded every few years to stay ahead of the industry's obsolescence cycle. Both of these processor lines are sustained and upgraded by Honeywell to prevent cost to the customer for significant life-time-buy expenses."

Honeywell designs their main "processor boards completely in house, rather than buying them from someone like Curtiss-Wright Controls Embedded Computing or GE Fanuc Intelligent Platforms, Walker says.

"We do not sell these boards to anyone but ourselves," the products are completely in-house," Walker says. "We make the boards and they run on Pentiums, PowerPCs, etc.," depending on the system, he says.

Another big cost factor in avionics development is managing the software that runs on each piece of hardware, Walker says. Every time a core hardware component is changed in the system – whether it is a GPS or a flight computer – the software running with it may have to be re-certified or even rewritten, which can be quite costly.

This is why many engineers always push for hardware to be independent of software in open architecture avionics systems, he says.


P-8A Poseidon

The open architecture approach is what Honeywell engineers are taking with the avionics on the Navy's new P-3A Poseidon aircraft, which is slated to replace the P-3 Orion maritime and patrol aircraft sometime in the next decade, Walker says.

Boeing is the prime contractor for the P-8A and according to its P-8A website the aircraft is a long-range anti-submarine warfare, anti-surface warfare, intelligence, surveillance, and reconnaissance aircraft. It possesses an advanced mission system capable of broad-area maritime, and littoral operations. It is also an armed platform, according to the web site.

The P-8A is based on the Boeing 737 airframe and cockpit, which Honeywell also provided the avionics for, Walker says. "We took the 737 avionics and militarized it for the Navy."

This is similar to what Honeywell did by taking commercial avionics for business jets and ruggedizing them for use in NASA's Orion space program, but the P-8A was not as big a leap since the cockpit itself is very similar to the 737, he adds.

Militarization includes meeting Mil-STD 881 and other requirements such as electro-magnetic interference (EMI), Walker says. There is a lot of complicated electronics in a tactical aircraft such as the P-8 and it needs proper shielding, he adds.

Honeywell engineers also reduced light emissions in the cockpit because the P-8 pilots will be wearing night vision goggles at times, he adds. The aircraft also flies into some very hazardous environments and the electronics also needed to be stabilized for shock and vibration, Walker notes.

Beyond meeting these technical standards, Walker declined to detail more specifically how the avionics were militarized.

Honeywell avionics on the P-8A include cockpit displays; display processing; air data inertial reference unit (ADIRU), and an enhanced ground proximity warning system (EGPWS), according to a Honeywell data sheet.

The ADIRU has an automatic gyro/accelerometer calibration lowers maintenance cost provides automatic re-alignment that eliminates the requirement to manually select down-mode align between flights or while waiting for dispatch and its gyros have a mean-time between failure rate of 250,000 hours, according to a Honeywell data sheet.

Displays provided by Honeywell for the P-8A include three B737-800 LRU display units; three Modified B737-800 LRU display units with video; two B737-800 LRU display electronic units with software modules; two modified B737-800 LRU EFIS Control Panels (EFISCP); and two B737-800 LRU remote light sensors, Walker says.

P-3 Orion and E-2C Hawkeye meeting international ATM requirements

Engineers at Rockwell Collins in Cedar Rapids, Iowa, have upgraded the avionics on the Navy's P-3 Orion Maritime Patrol Aircraft and the E-2C Hawkeye to meet international military and civilian airspace standards for U.S. Navy's functional requirements for communication, navigation, and surveillance for air traffic management (CNS/ATM), says Harry Oakley, principal marketing manager for special mission, search and rescue aircraft for Rockwell Collins in Cedar Rapids, Iowa.

Navy aircraft have to get anywhere in the world quickly whether for "battle, reconnaissance, medivac or what have you," and they need to be cleared to fly in various airspaces over Europe, the Mediterranean sector, etc., Oakley says. The Navy performs major operations in these airspace and if aircraft are cleared they will not get overfly rights."

The aircraft's global position system (GPS) inertial navigation system (INS) must be compliant to each certification organization such as the Federal Aviation Administration, the European Aviation Safety Association (EASA), etc., Oakley continues.

For this effort Rockwell Collins engineers not only updated the GPS, INS but the common display units (CDUs) as well since it displays information from the civil and military flight management systems that enables the P-3 to fly anywhere, Oakley says.

"The CDU is a control display unit, not a display," he notes. "The CDU is a key pad with a window to see what you are entering."

The avionics software on the P-3 is also certified to FAA and EASA requirements, Oakley says.

Safety certification of COTS software prohibits using operating systems such as Microsoft Windows, says Mike Bell, chief engineer for Lockheed Martin Maritime Surveillance Aircraft in Eagan, Minn. It is not worth it for Microsoft to spend the money ensuring Windows meets FAA DO-178B safety requirements for software, he adds.

The Navy is not done making incremental improvements to P-3 cockpit systems such as the flight management systems and displays, says Mike Fralen, program director and market segment lead for maritime surveillance aircraft at Lockheed Martin in Eagan, Minn. Lockheed Martin is the prime contractor and systems integrator on the P-3 program.

Upgrades to the P-3 cockpit are put in a piece at a time, there is not one whole new cockpit for the P-3, Fralen says.

Even when the P-8A officially takes over the main duties of the P-3, the Navy will still use the aircraft for AWACS (airborne early warning and control system) types of applications, Fralen says. Other U.S. Agencies such as the National Oceanic and Atmospheric Administration (NOAA) and Customs and Border Protection Agency will be using versions of the P-3 also, Fralen says.

"The P-3 will continue flying for a long time," Lockheed Martin's Bell says.

However, the biggest users of the P-3 for the next few decades will be foreign militaries, who will also require upgrades to the avionics systems, Fralen says.

The key to all future avionics upgrades designs is making sure the systems are based on an open architecture that embraces COTS technology and standards, Oakley says.

You can buy a commercial radio system and call it COTS, but it will not meet the CNS/ATM compliance requirements, Fralen says.

"We're even more into COTS with the tactical computers in the back of the airplane," Fralen says. Cost wise there was really no choice, and to battle obsolescence Lockheed Martin makes sure open architectures designs are used, he adds.

At Rockwell Collins their open architecture approach is called MOSA or modular open systems architecture, where avionics systems are designed in modules that are independent of the whole system so that when one is replaced it does not affect the entire avionics suite or require the avionics software code to be re-certified, he says.

"Our displays on the P-3 are a 5X5 called the MFD-255, with on each side," Oakley says.

According to a Rockwell Collins data sheet, the CDU-7000 features a color active matrix liquid crystal display (AMLCD), Power PC processor, and 3U Compact PCI compatible circuit cards. The unit consolidates control of communications, navigation, weapons management, and defensive aids equipment into a central point including the aircraft's flight management functions. The CDU-7000 features also include a more powerful processor, ARINC 739 capability (required for meeting future Global Air Traffic Management (GATM)), and a high tactile feedback sealed, fluid-resistant keyboard for turbulent mission environments.

The CDU 7000 replaced the older Rockwell Collins CDU 800 in the E-2C cockpit, Oakley says. They also added ARINC 429 and MIL-STD 1553 databus interfaces, he adds.

"The display on the Co-Pilot's side of the E-2 C is our MFD-2912, 9 by 12 display, which enables the flight crew to see tactical data from operators in the back," Oakley says. This provides the crew with a lot more situational awareness in the cockpit and is more efficient in terms of performance and safety."

On the P-3 Rockwell Collins also added new radios and tactical data links as part of an obsolescence upgrade, Oakley says. According to a Rockwell Collins release the upgrade replaced dual High Frequency (HF) radios and Link 11/TADIL-A Tactical Digital Data Link converters with 400W HF-121C HF Transceiver, known as the AN/ARC-230, and the MX-512PA Link 11/TADIL-A Modem, known as the AN/ASQ-130(V). DRS Communications Company in Wyndmoor, Pa., is a subcontractor to Rockwell Collins for the Link 11/TADIL-A modems. The contract also includes options to install Rockwell Collins' HF Messenger email capability.

Right now there are no plans to go to a complete glass cockpit in the P-3, Oakley says. Currently "the engine instruments for the P-3s are still round dials.

"We will have to see how it plays out in the P-3 program, if the Navy wants to spend the money increase the size of the glass, he says. "If they do it will bring more situational awareness into the cockpit and make the displays easier to read, he notes.

"I'd sure like to see the P-3 become a completely glass cockpit, but its probably not going to happen as the Navy wants to end-of-life it in 2019," Fralen says.

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