Plane & Pilot
Tuesday, July 28, 2009

Honeywell’s KFD 840

A cool new six-pack in a box

Eight pounds. Doesn’t sound like much. But aviators understand the significance of weight—particularly decreasing it. We consider weight in equipment decisions: Something new better do more if it weighs more. If it weighs less and does more, well, now that’s a score. Add affordability and you have a hat trick.

Honeywell designed the eight-pound KFD 840 integrated flight display to replace the standard six-pack of primary flight instruments and a couple of NAV indicators. And it scores on all three points: It weighs less than what it replaces, adds functionality and meets the value equation. But complexity isn’t one of its features.

The KFD 840’s large, bright 8.4-inch-diagonal color display brings alive its functions; it works smoothly and seamlessly in flight, provides new and useful features—and needs little effort to learn to use. Honeywell scored all these points and what may be the KFD 840’s biggest breakthrough: a price under $17,000.

Everything You Need (& Some You Might Need)
A technology known as “MEMS” underpins the KFD 840. It has been more than a decade since Honeywell embraced the benefits of MEMS—or microelectromechanical systems—for motion and attitude sensing.

For the heart of the KFD 840, Honeywell integrates MEMS technology into a low-cost, high-reliability and compact ADAHRS (air-data attitude and heading reference system) that drives the system. The ADAHRS senses the airplane’s altitude, airspeed and vertical speed, plus, as the name implies, its motion around all three axes—roll, pitch and yaw—and its magnetic heading. A separate external sensor provides heading information to the KFD 840 and serves as the compass module to provide heading stabilization for the heading readout.

An important design element of the KFD 840 ADAHRS is that the AHRS (attitude and heading reference system) continues to provide attitude and heading information independent of an air-data or pitot-static input fault. Thus, the KFD 840 continues to function when other systems stop because they need air-data input for the ADAHRS to work properly. In the event of an air-data failure, the KFD 840 puts a red “X” where the air-data readouts play on the unit’s screen. And it’s quite a screen.

Display Dominance: How Does 32 Inches Sound?
The KFD 840’s high-resolution color display measures a sizeable 8.4 inches diagonally—larger than other options and slightly smaller than some more expensive choices. This screen size allowed Honeywell’s engineers to give the pilot an attitude indicator (AI) display that’s seven full inches wide and 3.5 inches tall, with air data displayed on opposite sides: airspeed and airspeed bugs on the left; vertical speed, altitude and altitude bugs on the right.


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