Several years ago, the most popular add-on during major avionics upgrades was an electric attitude gyro. Paranoid owners who dreaded vacuum failure bet their lives-or at least a couple of grand-on electrically-driven steam gauge horizons for backup. But in a full-glass suite like the G1000 or Entegra, a steam gauge seems so old school. The mini glass backup instruments you see in transport-category aircraft are trickling down to Part 23 aircraft. Currently, two manufacturers have approved products: L-3 Avionics with the pricey Trilogy Electronic Standby Instrument system, and Kelly Manufacturing with the RC Allen with the more basic, and cheaper, 2600 electronic horizon. These units are opposite ends of the market.
L-3 Trilogy ESI-1000
L-3 Avionics (and former BF Good-rich) boasts a proven track record for extremely reliable electric, analog instruments. You find them in high-end business jets and in airliners, too. The ESI-1000 integrated standby system follows in high-end L-3 tradition. Its an impressive instrument with an impressive price of $15,000.
Despite the heavy price tag, Trilogy is generating lots of intrigue among glass cockpit owners. Trilogy can back up a big-screen PFD or old-school steam gauges, and has multiple TSO approvals applicable to various flight-instrument functionality including Airspeed, Attitude, Altimetry, Heading and Multi Purpose Display.
The standalone unit weighs less than three pounds and has a 3-ATI chassis with a front bezel that measures 4.03 inches by 3.35 inches. The system takes aircraft pitot and static pressure through two ports located on the back, and has an integrated air-data computer and solid-state attitude sensor. There’s a single electrical interface connector for a straight-forward installation.
While the unit can fit in the lower subpanel (the area you often find backup steam-gauges in glass-cockpit aircraft), the installation manual and STC with Approved Model List requires placement within the pilots normal field of view. We think pilots would want the unit front and center anyway, because the display is easy on the eyes and capable of primary navigation (See sidebar). Plus, the intent is using it for primary reference when the big glass goes dark.
The display is an auto-dimming (through a bezel-mounted photocell), 3.7-inch, color LCD with a 160 x 120 pixel resolution. L-3 told us the system is completely flicker-free since the processor has a 60 Hz refresh rate. One of the complaints weve heard from Aspen EFD1000 owners is a flicker in the display that contributes to eye fatigue.
There are four softkey buttons contained on the bottom of the Trilogy bezel that access various functions including baro setting, menu options and pilot-controlled brightness. Trilogy was designed primarily for 28-volt electrical systems, but it can be used in 14-volt systems via an external voltage converter.
More Than a Horizon
The attitude display mimics a traditional artificial horizon with blue sky and brown