Avionics News September 2015 - 19

below what the FAA requires. We know it happens.
This standby alternator method mentioned above is
arguably the surest, easiest path to gaining the power
needed to survive a generating system failure in IMC.
Dual alternators of matching capacity is increasingly
common on certificated factory aircraft with glass panels;
adding dual alternators is an option for some aircraft,
but will likely require a field approval using Form 337.
Copying an existing, previously approved dual-alternator
system can help that process.
A second alternator necessarily entails a different
regulator to monitor system power and activate the
standby alternator when the primary alternator's output
falls below a set level.
A controller that also provides for a warning or
annunciator light in the panel is a must to help manage the
load on the standby alternator.
Other options available include an RAT, or ram air
turbine. With this approach, an air-driven alternator is
installed inside the airframe - fuselage or beneath a
wing - with a control handle in the cockpit that deploys
the RAT when needed and assures power for as long as
adequate air flows through the turbine blades.
Again, a cockpit indicator to help manage the load is
needed to avoid overloading the alternator.
SECOND BATTERY, SECOND BUS, SAME OUTCOME
While a second alternator may be difficult to execute,
adding a dedicated standby battery and a second bus
to connect components can be the solution to needing
redundant power for that all-glass cockpit so appealing to
today's pilots.
Options for adding a second battery continue to
increase thanks to newer battery technologies moving into
aviation.
An option gaining ground in both certificated and
experimental aircraft is a standby battery dedicated to
digital-panel components, such as the PFD and MFD.
These batteries tend to be smaller, lighter, with more
mounting options; assuring the power can get to the main
or standby bus typically means adding a new breaker and
a connection to the charging circuit to keep the battery at
full charge.
Adding a second main-ship size battery is another
option employed, with or without a standby bus. How
the battery is switched and charged can be worked out to
the satisfaction of the Federal Aviation Regulations and
add depth to the aircraft's power redundancy with fewer
complications than a second alternator.

SELF-BACKING EFIS
Some of today's most-popular glass-cockpit options
offer their own standby battery systems to keep them
running in the event of a loss of electrical power -
whether a total system loss or a mere generating-source
failure.
Some provide their own integral standby battery power;
others offer a plug-in battery option; a few offer both,
increasing the time the EFIS instruments can run after
losing ship's power.
Assuring power to both a PFD and MFD can help
prevent a situation in which a loss of ship's power fails
one of the two and puts the other into reversionary mode -
where its capabilities and utility may be severely limited.
This solution may not keep alive the radios, but the
GPS systems integrated into many a MFDs can provide
navigation enough to get on the ground - with the added
comfort of knowing that the EFIS' integral standby power
isn't adding to the drain on the main-ship battery.
Standby battery power can keep a VHF comm and
panel-mounted GPS of VHF nav operating long enough to
land before they fail from lack of power.
But for added comfort in an electrical-system crisis,
nothing beats the utility of a handheld communications
transceiver - particularly one that can be plugged into a
jack feeding an external, airframe-mounted antenna.
To be of real help to the pilot, those 5 watts of
transmitting power need all the help they can get - and the
pilot will be better able to hear responses to his crisis calls.
A handheld is common as a backup in pilots' flight
bags, so it should be an easy sell for the avionics shop to
add that external antenna and the in-cockpit connection to
the transceiver's antenna jack.
Add a headset patch cord to the handheld, and the pilot
is closer to a normal communications link than possibly
trying to transmit through an airframe on a rubber-ducky
antenna.
KNOWING THE NEED
Upgrading to digital glass and dumping the weight and
recurring maintenance of analog - particularly analog
gyro instruments - is a growing desire among active
pilots. Some, though, come into the process unaware of
the redundancy and backup requirements of the FAA.
With help from the avionics shop, the aircraft owner
can fly away with that dream panel, IFR legal, but without
the worry of an electrical-system or flight-instrument
failure befalling them at the worst possible time. In IMC
with miles to go to a landing option. q
avionics news

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september

2015

19



Table of Contents for the Digital Edition of Avionics News September 2015

Avionics News September 2015 - Intro
Avionics News September 2015 - Cover1
Avionics News September 2015 - Cover2
Avionics News September 2015 - 1
Avionics News September 2015 - 2
Avionics News September 2015 - 3
Avionics News September 2015 - 4
Avionics News September 2015 - 5
Avionics News September 2015 - 6
Avionics News September 2015 - 7
Avionics News September 2015 - 8
Avionics News September 2015 - 9
Avionics News September 2015 - 10
Avionics News September 2015 - 11
Avionics News September 2015 - 12
Avionics News September 2015 - 13
Avionics News September 2015 - 14
Avionics News September 2015 - 15
Avionics News September 2015 - 16
Avionics News September 2015 - 17
Avionics News September 2015 - 18
Avionics News September 2015 - 19
Avionics News September 2015 - 20
Avionics News September 2015 - 21
Avionics News September 2015 - 22
Avionics News September 2015 - 23
Avionics News September 2015 - 24
Avionics News September 2015 - 25
Avionics News September 2015 - 26
Avionics News September 2015 - 27
Avionics News September 2015 - 28
Avionics News September 2015 - 29
Avionics News September 2015 - 30
Avionics News September 2015 - 31
Avionics News September 2015 - 32
Avionics News September 2015 - 33
Avionics News September 2015 - 34
Avionics News September 2015 - 35
Avionics News September 2015 - 36
Avionics News September 2015 - 37
Avionics News September 2015 - 38
Avionics News September 2015 - 39
Avionics News September 2015 - 40
Avionics News September 2015 - 41
Avionics News September 2015 - 42
Avionics News September 2015 - 43
Avionics News September 2015 - 44
Avionics News September 2015 - 45
Avionics News September 2015 - 46
Avionics News September 2015 - 47
Avionics News September 2015 - 48
Avionics News September 2015 - 49
Avionics News September 2015 - 50
Avionics News September 2015 - 51
Avionics News September 2015 - 52
Avionics News September 2015 - 53
Avionics News September 2015 - 54
Avionics News September 2015 - 55
Avionics News September 2015 - 56
Avionics News September 2015 - 57
Avionics News September 2015 - 58
Avionics News September 2015 - 59
Avionics News September 2015 - 60
Avionics News September 2015 - 61
Avionics News September 2015 - 62
Avionics News September 2015 - 63
Avionics News September 2015 - 64
Avionics News September 2015 - 65
Avionics News September 2015 - 66
Avionics News September 2015 - 67
Avionics News September 2015 - 68
Avionics News September 2015 - 69
Avionics News September 2015 - 70
Avionics News September 2015 - 71
Avionics News September 2015 - 72
Avionics News September 2015 - 73
Avionics News September 2015 - 74
Avionics News September 2015 - 75
Avionics News September 2015 - 76
Avionics News September 2015 - 77
Avionics News September 2015 - 78
Avionics News September 2015 - 79
Avionics News September 2015 - 80
Avionics News September 2015 - Cover3
Avionics News September 2015 - Cover4
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