Avionics News January 2016 - 29
Installation considerations, continued ...
with digital come other sensitivities
Many avionics shop technicians consulted for this story
stressed that with newer avionics come an increased need for
shielded wiring behind the panel - particularly for any wiring
that carries sound or digital signal.
And the more changes being made, the more important the
need to make sure wiring is healthy and up to the tasks asked
Giving the customer a detailed estimate that outlines the
time involved can help avoid confusion and possible hard
feelings when the invoice is issued, as well as helping the
customer understand why an ostensibly "plug-and-play"
audio panel upgrade needs hours of labor, because the owner
failed to take into account the need to rewire the intercom
connections and install new stereo-capable headset jacks.
It's better to learn up front that the owner can live with
monaural sound if it saves the shop labor and materials to rewire four to six intercom stations, string new three-conductor
wiring to each of the intercom jack sites, and all the interior
removal and replacement involved to accomplish the tasks.
Add to this the hour or two of work to rewire each radio or
device changed, and leave behind any talk of the job being
just a simple audio panel replacement job.
Finding what they need ... a shop's first service
The most important questions to answer when planning an
audio panel installation or upgrade is the most basic in aviation: What do you need it to do for you?
The answer naturally varies customer by customer, airplane by airplane. No two panels exactly match - and no two
pilots want exactly the same things.
For the VFR flyer using a simple panel to pilot two or
four seats, an audio panel may not even be needed - though
intercoms are almost always useful.
A stand-alone intercom can handle the needs of the simpler airplanes - ones with a single comm and GPS. Add a
single VHF nav, though, and suddenly a way to channel the
audio - to help the pilot positively identify the station tuned -
and a simple audio panel becomes helpful.
The number of audio inputs needed provides a definable
need to help with the selection. A panel with two comms,
two navs, an ADF and another non-VHF comm (such as an
HF transceiver) pushes up the number of switched inputs
required to connect everything.
For those, a larger, more conventionally sized audio
control panel delivers the needed features - from stereo
intercoms to music inputs, Bluetooth connections for phone
or music devices, plus a marker-beacon receiver with lights
For example, Avidyne's new AMX240 is a full-featured
audio source selector panel, intercom, and marker-beacon
receiver that provides outstanding features and sound quality,
while incorporating Avidyne's "Flying Made Simple" user
interface. Large, easy-to-read, LED back-lit buttons provide
simple mode selection and at-a-glance annunciation of your
current audio and intercom configuration. The AMX240 supports three transmitter inputs, nine receiver inputs, plus two
inputs for stereo music and another five unswitched inputs.
Avidyne also gave the AMX240 a six-place high-fidelity stereo intercom, public address function, plus Bluetooth music
and full-duplex cellphone interfaces.
The BendixKing KMA 30 features secondary radio
monitoring options like isolate mode, which ensures that
communications on the primary radio are always heard; the
secondary entertainment radio is automatically muted when
frequency transmissions overlap. It has pilot-controlled Bluetooth integration with cellphones, and portable entertainment
devices eliminates the need for interface wires in the cockpit,
as well as digital recording and playback of recent radio traffic, and offers flexible radio and music distribution to adjust
where different audio channels play.
Garmin's latest, the GMA 350c, offers general aviation its
first access to selectable three-dimensional audio. As Garmin
explains it, 3-D audio makes it seem like different audio
sources are coming from different directions so you can easily distinguish one source from many. For example, Comm
1 can be coming through the left side of the headset while
Comm 2 seems like it's coming from the right.
The GMA 350c also offers voice control over device
selection for hands-free control of the panel. Other variations
on the 350 model include marker-beacon receivers, but all
include integral intercom functions.
And two different audio inputs can be wired through the
back connector, while a third can be connected via a frontpanel 3.5 mm stereo input jack.
PS Engineering offers multiple options, one that can
mount in a space as small as a 2.5-inch instrument hole. The
PMA4000 is a TSO'd solution offering a four-place monaural intercom and audio control for two transceivers and two
navigators. No marker-beacon receiver - but audio control
and intercom for under $900, plus installation. A version with
digital clearance recording still comes in under $1,000 - plus
installation, of course. At the other end of the scale, PS Engineering offers several larger, more-feature rich models with
integral Bluetooth, hardware inputs, marker-beacon receivers
and intercom functions.
One, the PAC24, is designed as a plug-and-play replaceContinued on following page