Every certified glass panel airplane needs backup flight instruments. Aircraft manufacturers and some glass cockpit owners are making the switch from traditional, round-gauge mechanical backups in favor of all-in-one backup EFIS systems.
The way we see it, if the primary flight data fails, you might only need backup attitude data to help you keep the wings level. Still, an all-in-one backup might be the difference between an emergency or comfortably motoring along to the destination. That’s because a backup EFIS functions as a mini PFD, presenting six-pack data on one screen in a format that’s nearly identical to the primary flight display. Not only does this eliminate awkward, partial panel scan, it offers additional gee-whiz appeal. But pricey proposals for installation can hinder upgrades for lesser aircraft. If these things were priced a few grand less, we think they would fly off shelves in record numbers.
Everything you want to know about the installation of electronic flight instrumentation can be found in the FAA’s Advisory Circular 23.1311-1C. The guidance in this AC is directed toward aircraft and avionics manufacturers, operators and modifiers of Part 23 category aircraft and covers primary and backup instruments. You’ll have to dig deep into the guidance to find information on backup systems, but it’s there. Section 8.5 says, in summary, that for Part 91 and 135 flights made under IFR conditions, backup attitude information is required. Section 8.7 goes on to say that for electronic displays—which is the familiar PFD found in OEM and retrofit panels—a standby, integrated display of altitude, attitude and airspeed is acceptable, in place of individual backup instruments. That’s backup EFIS.
But like primary displays, backup instrumentation needs to be certified, carrying appropriate TSO for each function. This means experimental and portable EFIS displays and tablet apps won’t qualify, although as we explain in the sidebar on page 22, some of these inexpensive gadgets are more than capable of saving the day when a high-priced primary system lets you down.
L-3 TRILOGY ESI
Starting at $14,995, the ESI-1000 Trilogy brings traditional L-3 reliability and durability. Since the Trilogy ESI is certified to Design Assurance Level A and is covered by a liberal AML-STC, it’s suitable for the panel of a jet, turbo prop or piston single, although its high price tag has made the unit an easier sell in higher-end applications. The standalone ESI weighs less than three pounds and is built in a 3-ATI chassis, with a front bezel that measures 4.03 inches by 3.35 inches. The system uses aircraft pitot and static pressure via 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 straight-forward wiring. The Trilogy works on 28 volts but can play in 14-volt aircraft if used with an external voltage converter.
We like the Trilogy’s high-end display, which is an auto-dimming 3.7-inch diagonal, color LCD with 160 x 120-pixel resolution. Thanks to its speedy processor with a 60 Hz refresh rate, the display is completely flicker-free.
The Trilogy ESI-1000 falls short in being considered a true PFD since it doesn’t display navigational data, but it can display heading information. This requires the optional MAG3100 remote magnetometer. This is a three-axis, magnetic field sensor that inputs to the display via an RS-422 databus. The sensor is installed inside the fuselage or inside a wing, while adding considerable effort to an installation.
When the magnetometer is used, a heading tape appears at the bottom of the display, which moves left and right following the direction of the aircraft, referencing magnetic north. The ESI-2000 model has a backup lithium-ion battery, bumping the base price to an impressive $15,700, not including the $5480 heading sensor.
Mid Continent Sam
The $10,600 MD302 SAM standby attitude module is the result of Mid Continent Instrument’s experience building instruments for both OEM and aftermarket, including transport applications. The digital SAM picks up where the proven mechanical LifeSaver series electric horizon gyro left off. The MD302 has a high-end feel and seems well matched for turboprop and light jet panels, although it’s aimed at the piston market, as well—evident by its ability to play in 14-volt electrical systems. At 2.3 inches high and 5.5 inches wide, the four-in-one instrument is compact enough for tight panels, with dual 2-inch displays and a single push-and-turn function knob for navigating menu screens.
Speaking of turboprops, Elliott Aviation has recently won STC approval for the installation of the SAM for backing up retrofit G1000 suites in King Airs. In these applications, the SAM replaces all of the previously used traditional backup flight instruments. The unit uses an internal lithium-ion backup battery for powering the unit for over an hour, in case the electrics go out. The battery is constantly recharged when the unit is receiving input voltage.
The SAM uses a bright, high-resolution LCD display which is visible at wide viewing angles. It also has an installer-configurable data orientation called AnyWay, allowing for vertical or horizontal mounting in the instrument panel. The SAM is smart enough to communicate over an ARINC 429 databus—allowing interface with a compatible primary display for synchronizing baro settings, for example.
The SAM displays attitude, airspeed, altimeter and slip information, plus programmable airspeed range markings. There’s also a user-adjustable lighting threshold and auto-dimming. The SAM has a 2000-hour and two-year warranty.
If Aspen’s Evolution Backup EFIS looks familiar that’s because it’s packaged in the familiar, Evolution hardware, with data and bezel controls in a horizontal configuration. Aspen offers the Backup in two flavors—the Basic model and Advanced model. The Basic version follows the lead of Aspen’s entry-level Pilot PFD, providing all six-pack flight instrumentation, GPS flight plan when connected to a an external GPS, plus display of real-time winds aloft, OAT, TAS, and ground speed. The Advanced backup adds advanced navigational capability, including autopilot interface and electronic HSI for interfacing with analog and digital nav radios. It even has GPSS steering. Equipped with an internal emergency backup battery, both the Basic and Advanced Evolution Backup displays can power up for a minimum of two hours.
We think the only advantage of going with the Evolution Backup over a traditional Aspen display is the ability to mount the unit in a horizontal configuration. The Aspen Basic Backup is expected to sell for $6995 and the Advanced Backup for $10,995. This pricing is in line with the Evolution Pilot and Pro PFD systems.
Perhaps the most complex part of installing a backup EFIS system is the panel work. While these all-in-one units can fit the space occupied by three traditional round gauge instruments, shops still need to deal with metal and finishing work. The exception could be Aspen’s Backup, which has a rear chassis design that can fit into existing instrument holes, like its big brother primary Evolution display. However, the Basic Aspen Backup, like the L-3 Trilogy, uses a remote heading sensor, which can snowball a project, especially for composite aircraft. Aspen’s Advanced Backup unit is essentially the same as installing an Evolution Pro PFD—requiring a remote heading sensor and in many cases, an analog converter unit for nav and autopilot interface. The Mid Continent SAM and basic Trilogy, on the other hand, are mainly standalone, needing power, ground and pitot and static source inputs. For interfacing with databuses, the Mid Continent SAM will require more intense wiring. Our advice is to install these systems while the panel is opened for other work, especially when retrofitting primary glass.
MORE THAN EYE CANDY
While a total glass panel has modern appeal, we talked with a handful of glass cockpit owners and all had at least some concern about losing their primary flight instruments, and having to fly the inconveniently positioned steam gauge backups. “I learned to fly behind a primary flight display and to be honest, shifting my scan to the lower panel to fly the three ancient-looking backup gauges would be ugly,” said one Cirrus Perspective owner. Another owner, who flies a G1000 Baron, believes the $20,000 Trilogy install in his million-dollar twin was worth every penny, since he uses it for cross-checking the primary instruments. Since the PFD in his previous G1000 Cessna failed him in the clouds, he’s counting on his glass backup in the event of another primary failure.