Avionics News August 2017 - 19

from analog, while understandable, doesn't
Instrument pilots train for these losses, of course,
eliminate the prospect of partial-panel flying from
practicing partial-panel flying necessary to survive
an electrical-system failure.
the failure. When a failed suction pump deprives the
Instead, going all-electrical in the panel simply
attitude indicator of power to keep the gyro spinning
shifts the airplane from one with two inherent,
- just when the pilot most needs it - partial-panel
redundant failure points to one with a single point
flying provides a partial solution.
of failure: the electrical system. In a conventional
Partial-panel flying forces pilots to control the
panel, electrical-system loss costs only the turn gyro
aircraft attitude and direction by extrapolation
among the flight instruments
and interpretation of the
- though eventually the pilot
remaining gyro(s) and airwill also lose radios and
data instruments. Equally
navigation gear and lights and
unpleasant is the loss of
MOST AIRCRAFT
landing gear (in some cases),
electrical-system power.
PROVIDE
A
SINGLE
and every other electrically
Losing electrical power in
LEVEL OF ELECTRICALpowered item in the aircraft.
IMC means flying without
SYSTEM REDUNDANCY
Fortunately, electrical power
the turn indicator. In IMC,
is
one aircraft system with
losing the turn gyro makes
- THE MAIN-SHIP
multiple paths to gaining that
coordinating and controlling
BATTERY.
edge, or hedge if you will,
turns more challenging.
over the prospect of losing
Many instrument pilots opt
all electrical power. Many of
for a standby suction system
those same pilots who opted
to provide alternative power
for a standby air-power system
to the air-driven gyros. But
in their mixed-power panels
the issue of standby air power
also elected to add more depth
holds less relevance with
to the redundancy of their
each passing year.
electrical system by installing
The reason?
some form of an alternative
The advent of lower-cost
power source.
glass instruments is attracting
We'll examine the options
more small-aircraft owners
for adding electrical-system
looking for alternative
redundancy to that already in the aircraft - and
instrumentation - specifically instrumentation not
many of the options we portray here work equally
subject to the known frailties of the dry air suction
well in all-electric and mixed-power panels.
pump or in any way dependent on forced air flow.
Any serious instrument pilot would be well
The trend favors glass systems with no connection
advised to consider one of these electron-moving
to air pumps and plumbing; pitot and static
options for system redundancy. With suction and
connections are their only connection to the air at
air-driven gyros continuing to exit general aviation
all. These days, most new aircraft, from light sport
panels in favor of electrically powered instruments,
up to business jets, comes with a glass cockpit.
this article examines options for alternative
For the fleet aged 20 and older, analog still
electrical-power sources.
prevails. But options exist to change that
dependence on the analog six pack.
Continued on following page
Nonetheless, converting to digital instruments

DEPENDING ON
THE AIRCRAFT
AND OPERATION,
THE MAIN-SHIP
BATTERY MAY
NOT LAST LONG.

avionics news

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august

2017

19
Table of Contents for the Digital Edition of Avionics News August 2017
