Commercial, Military, Products, Public Service

Keep It Simple

By James T. McKenna | April 1, 2005

Advanced avionics applications have made their way to rotorcraft. Now the challenge is to make it easier and more cost-efficient to get them into aircraft and operations.

Avionics and aircraft manufacturers in recent years have succeeded in adapting to helicopter applications many systems developed for the larger fixed-wing commercial and corporate aviation markets. In the process, they've learned valuable lessons about how to best develop and field avionics and make them most useful to helicopter operators and pilots.

Those lessons can be boiled down to a common theme: keep it simple.


Whether it is wholesale change in a manufacturer's approach to designing and developing avionics suites, the retrofit of older aircraft with new cockpits, or the fielding of new warning or communications systems, the challenge for manufacturers and vendors remains the same. Come up with something that gives an operator or pilot the information he needs without requiring him to become a software engineer.

Across the board, companies are stepping up to the challenge.

Perhaps the most interesting development in this regard is Bell Helicopter's decision to change the way avionics will be integrated into its newest products.

Bell unveiled its newest aircraft, the 429 light twin helicopter, at HAI's Heli-Expo 2005 in early February. The aircraft, the GlobalRanger, has industry buzzing about its new design elements and market potential. Bell CEO Mike Redenbaugh intends the 429 to become "simply the benchmark for the light twin segment."

Initially aimed at the corporate and emergency medical services markets, the aircraft draws on technologies developed under Bell's Modular Affordable Product Line (MAPL) program, according to company officials. In fact, Redenbaugh said, Bell "accelerated the introduction of some of our MAPL technology by three years" to field the 429.

The most visible of these MAPL technology applications is the 429's cabin, Bell officials said.

With a volume of 220 cu. ft., it would be more than 70 percent larger than Bell's current light twin, the 427. The flat-floor cabin is designed, in an EMS configuration, to accommodate two patients with an attendant at the head of each.

It is to be equipped with clamshell aft doors to permit roll-on and roll-off of litters. The aircraft also is to be fitted with integrated sliding doors, which are designed to be wide enough to allow side-loading of patients. (Air Methods designed and installed the EMS interior and may be the 429's launch customer; it has ordered 15.)

With a 7,000-lb. max takeoff weight, the aircraft is designed to carry a useful load of 2,700 lb. in a single-pilot IFR configuration, have a range of 365 nm. with full payload and a top speed of 142 kt. It also is designed to hover in ground effect at 12,000 ft. and out of ground effect at 9,300 ft.

Bell plans to certificate the aircraft to the latest regulatory amendments as a single-pilot IFR, Category A helicopter, with fully coupled, three-axis autopilot. Dual-pilot IFR operations would be optional. The 429 is to have dual hydraulic systems in all three axes, new rotor technology (including a four-bladed tail rotor system for improved noise performance) and 1,100-shp. available from two Pratt & Whitney Canada PW207D engines.

First flight of the 429 is scheduled for early 2006. Bell plans to fly some of its components this year on a 427 test aircraft. Certification is planned for the first quarter of 2007, with first deliveries to follow shortly thereafter. Korea Aerospace Industries and Mitsui Bussan Aerospace Co. of Japan are risk-sharing partners on the 429 program. Bell will do final assembly at its facility in Mirabel, Quebec, and will handle flight-testing and certification.

The GlobalRanger replaces the 427i IFR aircraft, the plans for which Redenbaugh unveiled at the 2004 Heli-Expo. All 427i orders have been converted to ones for the 429. Bell has orders for 90 429s, about 80 of which are converted 427i orders.

If Bell's intentions for the 429 bear fruit, customers concerned about avionics-integration challenges should be pleased with that change. The GlobalRanger is the flagship of the company's effort to make it simple and easy for operators to customize the suite of avionics they select and use on the aircraft. Bell calls the new approach BasiX.

That approach will rely on an "open architecture" avionics system, which is not a new concept. Many such systems have been developed for military and civil avionics applications.

While the term "open architecture" may be a familiar one, it also is an overused and misused one. The concept behind it is a software system in which any component that meets a baseline technical standard, such as the ARINC 429 standard for avionics interfaces, is compatible with it. But in practice many systems promoted under the name "open architecture" have enough proprietary elements to make it difficult or impossible to integrate avionics from outside vendors.

Integration can be a major challenge even without such hurdles. Many an aircraft program has been delayed as software and aircraft engineers struggled to refine avionics' management of key systems to satisfy the needs of pilots and requirements of regulators.

With BasiX, Bell is tackling such problems head on. It is bringing in house the design of the "brain" of the aircraft, the digital acquisition unit, for the 429 and follow-on aircraft. Essentially the mission computer, this unit governs the performance and functions of the aircraft's flight control system, engines and navigation and communications systems.

This move runs counter to 20 years of industrial evolution in aerospace that has seen companies farm out "non-core" work to others that specialized in areas like software design in an incessant drive to improve production and financial efficiency.

The Bell change reflects recognition that the most critical skill in the avionics-integration process is familiarity with the aircraft, said Elaine Vaught, Bell's vice president and executive director of commercial programs, and that no one in the production process knows the aircraft better than the manufacturer.

Bell has used a similar approach before, developing open-architecture avionics for the Eagle Eye unmanned aerial vehicle ordered by the U.S. Coast Guard and Evergreen International Aviation, as well as for the flight control system for the U.S. Marine Corps' H-1 upgrade of Hueys and Cobras.

"Bell has lots and lots of experience in developing software for its aircraft," Vaught said. That makes it the best candidate to do what is required for the 429--design, prototype and gain certification of an effective and efficient mission computer. Once certification is in hand, Bell will have the unit built to print by a subcontractor. But it will be responsible itself for maintenance and modification of that critical unit's hardware and software.

Bell executives consider the BasiX approach essential to hitting their cost targets for 429 development. But customers will see the real payoffs of the initiative, they said.

The objective of BasiX designers is to "provide as many interfaces as we could, so any commercial application with an ARINC 429 interface can very easily be put into this aircraft," Vaught said. "So if you decided to add a weather radar, there's not going to be a huge development effort and a two-year delay" to get that avionics on the aircraft.

"That's a pretty big feature," she said.

In developing BasiX, Bell officials drew on past experience with avionics development projects, including the Eagle Eye and H-1 efforts and the AB139 medium twin fielded jointly with AgustaWestland under the Bell/Agusta Aerospace Co. banner. U.S. certification of the AB139 required a change from a three-display to a four-display instrument panel for its Honeywell Primus Epic integrated avionics suite.

The suite includes automatic flight control, electronic flight instrumentation system (EFIS), engine indication and crew alerting system (EICAS) and a full-range of communications and navigation radio systems. U.S. regulators insisted on the change before certificating the aircraft for dual-pilot operations, although European regulators were satisfied with the three-display set-up.

The required changes to the aircraft and its integrated avionics resulted in significant delays in FAA certification of the aircraft.

"The AB139 is one of many, many data points" considered in the decision to adopt BasiX and the ongoing development of it, Vaught said.

The BasiX integrated avionics on the 429, dubbed BasiX-Pro, includes as standard elements two large-screen, multi-function flight displays ready for use with NVGs; the dual digital, three-axis coupled autopilot with stability and control augmentation; state-of-the-art dual air data and attitude heading reference system; incorporation of all engine and system indications and crew-alerting systems into the glass-cockpit displays; electronic engine control; an electronic standby instrument system; dual navigation, communications and GPS systems with color mapping displays; an elementary surveillance-compliant Mode S transponder; a traffic information system, and a stereo-provisioned audio and intercom panel with marker beacon.

According to Bell, the BasiX system is designed to automatically perform power assurance checks and weight-and-balance, hover-performance, and Category-A calculations.

The new avionics system also is designed to do automated flight logging, storage of flight and operating times for the last 100 flights, generation of checklists that can be configured by the operator, and recording of exceedance and one-engine inoperative events.

The system is to have built-in provisions for acquisition of flight data recorder and HUMS data and automated diagnostic and maintenance aids. There also are to be provisions for a coupled fourth-axis upgrade to the autopilot, providing hover-altitude hold and low-speed coupled flight.

The 429 also is to have the on-screen programming in the cockpit to permit operators to load configurations for a variety of instruments and avionics units, from radar altimeters to terrain awareness and warning systems and forward looking infrared units.

"We expect it will simplify" the selection, installation and use of avionics for Bell customers, Vaught said.

A More Reliable Aircrane

Erickson Air-Crane also is working to simplify use of the S-64 Aircrane for its customers.

The company teamed with Heritage Aviation, Ltd. in Grand Prairie, Texas and SAGEM Avionics, Inc. to give the heavy-lift aircraft a new, more user-friendly cockpit and avionics suite.

The first of the upgraded aircraft should begin flying firefighting missions in the next few months for Corpo Forestale Dello Stato, the State Forestry Corps of Italy. That agency has ordered four of the upgraded S-64s, with options for two more.

Erickson had two main goals in pursuing the upgrades. First, improve the Aircrane's reliability by shifting to solid-state avionics and better sensors for its systems. Second, increase sales and revenue operations of the aircraft by making it more appealing to agencies and companies that might buy Aircranes or contract for their use. The latter required matching the capabilities, performance, safety and reliability of the newest helicopters in the marketplace.

The upgrade includes a Collins Pro-Line 21 avionics suite, new cockpit displays (including four Collins 5.4-in. LCD primary flight displays and two SAGEM 10.4-in. LCD multi-function displays that replace several "steam" gages) mounted on a vibration-isolated instrument panel. It also includes solid-state attitude heading reference systems, a new LED warning panel and a new flight control system.

The heart of the upgrade is that last system, the SAGEM PA 155 three-axis analog automatic flight control system. The system, basically the same one used in Eurocopter's SA332 Super Puma and AS365 Dauphin, was selected because of its proven history of reliability, according to Erickson officials.

It also was selected because of its ability to interface with the electro-valves, or Moog valves, that relay the pilot's control inputs from the flight control system to the S-64's main hydraulic servos. Erickson opted not to pursue development of a new flight control system to keep the cost of the upgrade down.

The flight control upgrade makes an S-64 pilot's life easier, according to company officials. The S-64 uses a duplex system developed by Sikorsky that permitted attitude hold to be coupled with heading hold or barometric altitude hold. This meant pilots did not have the option of going on hold in cruise flight. Pilots can fly hands off in cruise flight with the SAGEM system, which permits basic attitude retention or that coupled to heading hold and altitude or airspeed hold. It also allows attitude and automatic heading hold in a hover. The SAGEM system also has a stability augmentation system mode of operation that should be very useful for pilots conducting logging and firefighting operations, according to Erickson.

Mission-Specific Tools

Having gained certification for the upgrade, Heritage is producing modification kits for Erickson to use in doing the installations itself. The upgrade includes six supplemental type certificate packages. As part of the upgrade, Heritage developed an integrated caution display system that is a straight replacement for the S-64 warning panel.

The SAGEM ICDS 2000 multi-function displays allow the pilot to change the information displayed depending on what type of mission is being flown.

A firefighting screen, for instance, shows information on the water level in the 2,650-gal. tank, the position of the water cannon, and whether foam is on or off, as well as engine and power indications.

One problem with past avionics developments was the complexity of the information the black boxes conveyed and the manner in which it is conveyed. For many helicopter pilots, particularly those flying utility missions, it is critical that avionics tell them what they need to know in a timely manner and in as intuitive a form as possible.

"In a fixed-wing aircraft flying straight and level, if your whole world is the EFIS, that's okay," said Lee Benson, senior pilot for the Los Angeles County Fire Dept. For utility pilots, "you stare at an instrument panel in a helicopter and you'll end up in a world of trouble fast."

Benson said the key test for helicopter avionics is "it's got to be simple. How do you present information to a pilot who's earning his keep in a high-density air traffic environment in a way that tells him what he needs to know without interrupting his thought process for flying?"

Safe Flight Instrument Corp. is among the company's aiming to pass that test. It has developed a new system for warning pilots that they are approaching power lines. Its Powerline Detection System recently won FAA approval for installation in the complete range of Bell 206s.

The system senses the electromagnetic field radiated by live power lines. When it senses that field, the system emits what the company says is "an unmistakable," Geiger counter-like ticking in the pilot's headset that increases as the aircraft gets closer to the lines. A red warning light also illuminates on the instrument panel. Law enforcement, EMS, military, and commercial operators are currently evaluating the system.

Another group of companies offering tools to simplify the lives of operators and pilots are those that have developed satellite- and Web-based communications and flight-tracking services.

Since acquiring SkyConnect's Tracker systems for its seven Eurocopter AS350B2s, one Eurocopter AS355N and five Beech King Air C90s last year, for instance, air ambulance operator EagleMed has been able to improve the productivity, reliability, safety and customer service of its operation.

"It has revolutionized the way we do things and has had a huge impact on our operations and how we take care of patients," said Allen Zon, EagleMed's director of operations. The company covers six U.S. states from 10 air bases in Kansas, Missouri and Oklahoma. It flies more than 400 missions a month.

The Tracker system uses the Iridium satellite network to transmit flight tracking data and voice calls between the aircraft and dispatch center. The system also automatically transmits GPS-derived position, course and speed at user-prescribed intervals to the dispatch center.

In addition, flight crews have private two-way telephone capability through the satellites. Sky Connect's systems are integrated with EagleMed's Flight Explorer aircraft situational display software.

Metro Aviation is sold on OuterLink's Flight Tracking and Messaging System. The Shreveport, La. operator is standardizing its fleet of more than 40 air-medical aircraft with the system. It is to take delivery and install at least 30 units over the next two years. The OuterLink system provides 30-sec. position reporting, 3-sec. Mayday alerts and exact trip mileage reports.

The OuterLink system will allow Metro Aviation to manage the deployment of all aircraft equipped with OuterLink satcom data terminals from its home base in Shreveport.

In addition to providing dispatchers with real-time flight tracking data, the system also supports two-way digital messaging with pilots and provides flight nurses and paramedics with a communications interface for equipment such as laptop computers and patient monitoring devices.

SkyTrac Systems is the choice of Med-Trans Corp. to equip its medevac helicopter fleet with a flight-following system.

Sat-Phoning Home

Based in Bismarck, N.D., Med-Trans operates vendor helicopter programs as well as stand-alone bases throughout the United States. SkyTrac's system provides global, real-time automated flight following and two-way air-to-ground text messaging and enables the transmission of critical airframe parameters. It also offers a hands-free satellite phone voice capability through the Iridium system

AirCell's recently gained certification to RTCA's Category U helicopter vibration standard for its ST3100 satcom system, designed to provide high-quality voice and low-speed data service at all latitudes over the Iridium network.

AirCell also has added automated flight-tracking capability to its suite of airborne telecommunication systems using Flight Explorer software. Late in 2004, AirCell shipped its 2,500th telecommunication system. The company said its products are offered as standard or optional equipment by virtually every rotor-wing airframe manufacturer.

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