Avionics News August 2018 - 18

THE MODERN EFIS PANEL
Continued from page 17

be a minimum of 2 inches in diameter or, if combined, a minimum diameter of 3 inches displayed.
Then there's the need for a level of power redundancy for the
PFD - a second electrical source - at a minimum the main-ship
battery or a standby battery, or an emergency buss powered by a
second alternator or battery.
Both the PFD and that trio of standby instruments need the
security of a steady power source - except in the case of aircraft
that use the two old-style air-data instruments and an attitude
indicator to fulfill the FAA's redundancy requirements. Then
keeping the suction or air pump connected to the backup instruments is the way to go.
Standby instrument:
Mimicking the PFD has benefits
While using old analog airspeed, altimeter and attitude indicator has appeal - reduced costs and already in-hand - safety
experts encourage the use of standby instrument packs that present similarly to the main PFD.
Plenty of options exist to meet that suggestion.
Self-contained backup instrument packages provide a pathway to a complete glass cockpit for Part 23 fixed-wing aircraft
or a Part 27/29 rotorcraft, in a form similar to the PFDs they
back up.
For some pilots, adding a second, matching PFD fulfills the
need. That's particularly true of many users of Aspen Avionics
Millennium series of compact glass instruments. Three - two
PFDs and an MFD - can fit into the same space as most analog
panels' six-pack of instruments. Redundancy is assured and
standby power is built in.
L3 and Mid-Continent Instruments and Avionics both make
and market standby instrument packs designed to look and function the same as the glass PFD.
Mid-Continent Instruments and Avionics' SAM - Standby
Attitude Module - splits the AI from the air-data indicators, with
the multicolored attitude instrument in the left half while the airspeed and altimeter (along with its barometric pressure readout)
occupy the right half. That's in the horizontally-oriented SAM.
The company also offers the SAM package to mount vertically in the panel, with the AI on top. An integral standby battery is included, resolving the question about redundant power
for the SAM.
L3 Aviation Products offers a similar package in a
smaller form-factor - one that will fit in a single-instrument opening. Called the Trilogy Electronic Standby
Instrument, or ESI, the solid-state Trilogy ESI delivers attitude, altitude and airspeed information on a compact and
easy-to-read 4-inch by 3-inch display and easily replaces
traditional electro-mechanical standby instruments while
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2018

presenting the needed information on a single screen.
An internal battery is available in the ESI-2000 model,
providing a minimum of one hour of power in the event of an
electrical-system failure.
Aspen Avionics offers its backup package in two versions,
basic and advanced. Both offer the necessary capabilities to
serve as a backup package to a glass PFD; the advanced adds
several worth-considering features, including synthetic vision
system, an angle-of-attack capability, and an emergency GPS
navigator. Both also sport their own standby battery for power
redundancy.
Some pilots migrating to glass panels turn to Dynon for one
of its approved PFD packages, one of which is battery powered,
the other with a standby battery capability.
The case for standby power - part 1
A pilot needs more than reliable flight instruments in times of
emergencies, and standby power works to deliver an added level
of security for those other systems, as well.
While backup instrumentation may be a necessity for an allglass panel, of equal importance is standby electrical power.
In the event of a main-ship electrical-system failure, the benefits of a full-aircraft electrical standby power extend throughout
the aircraft and its systems.
The main battery provides a modicum of electrical-power
redundancy. But in an aircraft with nothing but electrically powered accessories, that battery may not last long.
In an emergency, the pilot needs those flight instruments -
and more: A navigation radio, for example, and a comm radio or
a GPS, and a transponder to help others see the aircraft.
Power to the transponder should be high on any pilot's list
so that controllers can continue to track a flight suffering an
electrical-system failure. Retention of navigation capability is
always a plus in any emergency.
Take it from experience, an electrical-system failure while in
the klag of an IFR approach is not recreational flying.
Should the failure come at night, however, enough power to
at least light the runway - or key up pilot-controlled lighting -
before turning short final would be welcome, as well.
Standby power - part 2
With more aircraft undergoing conversion to all electrical panels, and virtually all new-production aircraft similarly
equipped, equipping and maintaining alternative electrical
power is nothing less than a matter of survival - aside from the
FAA's requirements.
Electrical-power redundancy can take several forms:
* A second generating source to provide power at
least to a minimal amount of aircraft systems.
* A second battery, capable of keeping power flowing to a minimum set of systems - for example, a
PFD, a navigator, a comm radio and the transpon-

Table of Contents for the Digital Edition of Avionics News August 2018