Product Focus: Flight Data Recorders

Interconnectivity of avionics, including flight data recorders (FDR), is of prime importance to aircraft operators because it offers rapid data transfer rates and significant time savings. Thanks to increased use of Ethernet networking technology, already widely used in terrestrial networks, various avionics are now able to communicate with each other using standard Internet protocols.

The latest standards — such as ARINC 664, which defines the use of Ethernet as an avionics databus, and ARINC 767, describing an Enhanced Airborne Flight Recorder (EAFR) — are clear in assuming increased utilization of Ethernet in the airborne environment. The standards proposed in these documents will go a long way toward making it easier and less expensive to connect digital data devices.

Issued last October, ARINC 767 provides guidance for development and installation of an EAFR combining any or all functions of a digital FDR, cockpit voice recorder, data link recorder and image recorder in a single line replaceable unit (LRU). The document addresses interface and system standards, rather than overall flight-data recorder system requirements (Avionics, January 2007, page 44).

ARINC 767 also provides guidance for high-speed data acquisition, capture of video data and data transfer to the FDR at ever higher rates. The standard was written with the intent to be applied to an Avionics Full Duplex Switched Ethernet (AFDX) nework backbone, said Dan Martinec, ARINC project manager of flight recording systems.

Smiths Aerospace developed the first such EAFR complying with ARINC 767. The Smiths’s EAFR will fly aboard the Boeing 787 Dreamliner, scheduled for its first flight later this year. The Smiths EAFR is connected to the 787’s Common Data Network, an AFDX backbone, enabling the connection of sensors and avionics units with the FDR.

Airbus utilizes AFDX as the network backbone of its new A380. However, the airframer elected to use a flight-data recording system complying with ARINC 747, describing a FDR with solid-state memory, and ARINC 717, the standard for a digital, expandable flight data acquisition system, Martinec said. There is some conjecture in the industry that Airbus may eventually use an ARINC 767 recorder at a later time on the A380.

Expanded Usage

The standards set forth by ARINC 664 and ARINC 767 expand the usage of the flight data recorder to more than merely a crash or incident investigation tool through interconnectivity and rapid data transfer.

Larbi Ouchelouche, project manager at Speel Praha Ltd. in the Czech Republic, said the issues addressed in both standards "lead to a modern flight recorder that is interoperable with an ARINC 664 compliant Ethernet airborne network. And that is where all avionics systems today and in the future are headed."

Speel’s latest generation FDR, the Crash-Survivable Airborne Recorder (CARE), is a solid-state memory flight recorder designed with Ethernet capability and a legacy COTS operating system. Like other new generation recorders, CARE is lighter in weight and size, yet it still offers higher memory capacity and greater ruggedness than previous generation units.

By using a standardized, high-speed Ethernet connection, recorder manufacturers are able to provide more access to the data recorded within their units.

Data is now available to ground crews for review and analysis "within a matter of minutes," said Steve Leaper of Penny + Giles, a division of Curtiss-Wright Controls in Christchurch, U.K.

"This improves equipment and maintenance times," he said.

Also, Leaper says with the addition of data analysis functions to the replay system, the flight recorder system is able to operate as an active component within Flight Operations Quality Assurance programs.

Teletronics Technology Corp., Newtown, Pa., offers a variety of recorder products, including airborne Network IP-based recorders for flight-test programs operating at up to 2 gigabits per second (Gbps), with media capacity of up to 1,000 Gbytes.

Ouchelouche said FDR end users will benefit from "the use of ubiquitous tools such as Wi-Fi technology for wireless Ethernet-based data transfer via a standard infrastructure. Internet technology will allow use of the World Wide Web on the ground for data downloading and for transfer between the aircraft and the ground station and even from one ground station to another site."

Leaper adds that implementation of Ethernet interfaces for data download has reduced service times.

"Many older generation recorders do not support rapid data retrieval," he said.

In those cases, an operator performing its annual recorder system checks must remove the recorder from the aircraft, transfer the whole unit to a replay facility, replay the data, then return the whole unit to the aircraft for reinstallation.

"But, newer units (like Penny + Giles’ Multi-Purpose Flight Recorders) provide a high-speed Ethernet connection that downloads encoded data directly to a PC using a commercial standard interface. This information is then cut to CD and transferred to the replay facility while the recorder is installed back on the aircraft," Leaper said.

Operators he has spoken with, Leaper said, put the annual maintenance cost savings from this portion of the technology alone at $1,500.

Even larger savings are resulting from advances in processors and solid-state memory, and from the continued push to utilization of commercial off the shelf (COTS) technology. COTS allows recorder manufacturers to minimize size and weight of crash survivable memory units.

"The adoption of COTS is not a fashion, but a necessity imposed by the need to reduce costs and improve system capabilities. Design also benefits from well-defined standards for interoperability. COTS has allowed us to build systems that withstand harsh environments. It also allows us to profit from the high-performance products. COTS-based systems include not only hardware, but also software," Ouchelouche said.

Leaper credits COTS with advances in Penny + Giles’ latest Multi-Purpose Flight Recorder (MPFR). "The design of the MPFR utilizes advances in solid-state memory and processor systems while employing the latest COTS technology to minimize size and weight. The memory module contributes a major proportion of the weight of the equipment and (with COTS) the whole unit mass is significantly reduced compared to units using older technologies."

As a result, Leaper said the MPFR provides a 12-pound weight savings over previous generation recorders. An additional two pounds is saved because the MPFR mounts directly to the airframe, eliminating the need for racks. Leaper estimates the annual operating cost savings of installing a new MPFR to be about $500 per pound, or $7,000.

Both Leaper and Ouchelouche believe one of the disadvantages of COTS utilization is the possibility of obsolescence. While consumer electronics are continually being updated and consumers generally seem eager to embrace new technologies quickly, the avionics marketplace will not tolerate rapid retirement of parts.

"While there are many advantages with current technology," Leaper said, "there are also disadvantages, the most costly being obsolescence. With the boom in personal computers, mobile phones, MP3 players, etc., memory manufacturers are supporting the mass market, which changes very rapidly. Designs for avionics applications, though, are expected to be supported for years ahead."

The move to enhanced recorders complying with ARINC 767 also raises questions about fleet commonality and system reliability, said one recorder supplier.

Glenn C. Wilson, director of business development at L-3 Communications Aviation Recorders, said his company is working with a large manufacturer, which he declined to identify, to evaluate the ARINC 767 system concept as compared to the current industry standard for flight recorder systems.

"We do not view the development of an ARINC 767-compliant system as an overly complex technical challenge. We would expect to be able, if and when required, to design, develop and qualify a system within eight to 10 months of a formal project start," Wilson said.

"The users of such a qualified system, however, principally the airlines, are coming to the realization that the ARINC 767 standard may decrease certain avionics component choices that these same users have been accustomed to having when selecting new aircraft.

"Importantly, the forward-fit ARINC 767 standard implementation does not allow for fleet-wide commonality of flight recording systems that many airlines in particular have been striving hard to achieve over the past several years in concert with fleet consolidation and rationalization decisions. There are also some possible questions regarding the overall system reliability given that multiple LRUs can be required to implement the flight recording functions that now are performed typically in no more than three separate, interconnected boxes, and in some cases in only one," Wilson said.

Recording System Captures Pixels

An example of a technology made possible by recording advances is the DGy real-time digital recording system from RGB Spectrum, Alameda, Calif.

The DGy records pixels, not data, and can record and replicate all the visuals inside and outside a cockpit. The system captures, compresses, stores and plays back imagery at up to 2560 x 2048 pixel resolution. It accepts computer, radar, sonar, FLIR, X-ray, HD and other high-resolution signals, NTSC/PAL video, optional HD-SDI (High Definition Serial Digital Interface), and stereo audio.

The key to the DGy is its ability to reproduce symbology down to a single pixel, RGB Spectrum says. This allows intricate reviews of the visual field while maintaining intricate resolution.

The U.S. Army’s Future Combat System program will employ two DGy digital recording units in its training presentation room. The units can record battlefield simulations in real time at 1600 by 1200 resolution. The recordings are played back during presentations and after-action reviews.