Product Focus: Data Acquisition

By By Bill Carey | January 1, 2007
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Among new systems that will debut on the Boeing 787 Dreamliner is an Enhanced Airborne Flight Recorder (EAFR) manufactured by Smiths Aerospace, the first such recorder complying with the new ARINC 767 standard.

Adopted by the Airlines Electronic Engineering Committee (AEEC) last October, ARINC 767 provides guidance for development and installation of an EAFR combining any or all functions of a digital flight data recorder, 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.

In addition to Smiths Aerospace, Honeywell and L-3 Communications are among companies developing ARINC 767-compliant recorders.

Today's recording systems rely on flight-data acquisition units (FDAUs), standalone units that receive parametric flight data. The FDAU collects radio altitude information from the radio altimeter, barometric altitude and airspeed from the air data computer, and current position from the flight management computer. Those units send data through ARINC 429 buses to the FDAU, which assembles the information and sends it to the flight-data recorder.

Enhanced recording systems make possible a "virtual" FDAU, where the flight-data acquisition function primarily resides in software.

The Smiths’ EAFR is connected to the B787’s Common Data Network, an Avionics Full Duplex Switched Ethernet (AFDX) network backbone, enabling connection of sensors and avionics units with the flight data recorders. The FDAU function is a software module hosted in the EAFR.

"In this new world, the aircraft network takes care of all sensor interfaces, which means you don’t have a digital flight-data acquisition unit as a separate box," said Piet Ephraim, director of strategic development, information systems, with Smiths Aerospace. "The recorder takes the various pieces of data coming across the network and runs a piece of software, which does the same job as the old-fashioned flight-data acquisition unit. It’s software only, which is pretty neat."

The Smiths recording system consists of two crash-protected EAFR recorders, including one with an independent power supply to comply with the EUROCAE ED-112 requirement for minimum operational performance in the event of a power failure. The system includes an area microphone, positioned in the cockpit, to record ambient noise.

While Boeing will configure the FDAU function according to its requirements, the Smiths EAFR is capable of recording "in the thousands" of parameters, Ephraim said. This represents an order-of-magnitude improvement over current recorders, which record hundreds of parameters.

Another obvious advantage is the weight savings to be gained. Older flight-data recorder boxes typically weigh 15 pounds each, and two are needed. The FDAU is a 20-pound box. The Smiths’ system consists of lighter-weight recorders of about 10 pounds each, Ephraim said, and no FDAU hardware.

The Smiths EAFR also will be the first recorder to comply with the ARINC 767 standard and the TSO 177 digital data link recording requirement to record messages to and from the aircrew, Ephraim said.

Leading to the adoption of ARINC 767, there was discussion over defining a digital audio standard for recording purposes. That discussion is ongoing. AEEC’s Digital Flight Data Recorder Subcommittee determined that "material already included in the [EAFR] draft was adequate to perform the function," but that "some tweaking and expansion of the text would be necessary to ensure it was adequate as a standalone definition," states the summary of a meeting held last May.

"The digital audio definition is pretty much consistent with the latest draft of our digital audio standard," said Dan Martinec, ARINC technical director of Industry Activities. "However, the Digital Audio group has decided we need a digital audio standard that is universal and can be used across more platforms and have more application to navigation communications. The way it’s set up now, it really doesn’t complement navigation communications well.... We’ll probably have a different digital audio standard a year or two from now."

Further work also is planned to develop a standard format for the data retrieved from recorders. Recorder output formats now are unique for each manufacturer. Manufacturer-specific readout equipment extracts the information and translates it into useable engineering units.

Martinec said when work began on ARINC 767 in 1999, computer memory wasn’t as cheap and as dense as it is today. Manufacturers used different kinds of data compression and techniques to store data. The data wasn’t stored in true engineering units. Since the compressed data from the recorder output required unique processing to bring it back to engineering units, a standard output definition had been impractical. With the greater availability of memory now, there isn’t the need to compress data, which can be stored the same way it is received.

Package carrier FedEx has proposed that work begin on a standard data output format for recorders. That work was expected to begin in February.

While specifications associated with ARINC 767 remain in development, it is clear that the advantages offered by EAFRs will make them standard equipment on future aircraft, Ephraim said.

"The future’s very bright, because the capabilities of this [EAFR] are vastly superior to any of the previous recording systems," Ephraim said.

"It’s truly a revolution. The implementation of this is done in such a way that it is light — you’re saving weight, which is always a great advantage on an aircraft. You’ve got fewer boxes because you’ve eliminated the flight data acquisition unit, which improves your reliability and cost of ownership of the aircraft. So you’re getting more, it weighs less and the lifecycle cost is going to be less."




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