Avionics News July 2015 - 54

ARTISANAL AVIONICS

connector, exposing no bare wire. "When we made this
change, reliability increased significantly."
Solder sleeves cleaned up the attachment of the ground
wire to a cable's shielding braid, sealing the connection at
both ends. Most install manuals locate this connection as
close to the pin as possible, Dyk said, because digital avionics are sensitive to noise. "The shorter the ground wire,
the closer it is to the pin, the less chance it has of picking
up interference."
Configuration: A tech who reads and follows the manumanu
facturer's installation manual item by item, page by page,
is a true avionics artisan. This sounds simple, but many of
their page counts number in the hundreds. For the Garmin
G600, "just the configuration setup
is 100 pages," Dyk said. "Don't give
into the temptation to bypass this,
thinking 'I've done this a hundred
times before.' Missing any of these
details leads to problems down the
line, and that affects the shop's repu
reputation."

Continued from page 53

"Moisture is the killer of avionics no matter where they
fly," he continued. Because most of its aircraft operate
in hot, humid jungle climates (and sit outside when not
flying), MAF pays close attention to harness routes, the
location of avionics cooling fans (so they do not blow
moist air or drops on top of equipment), and possible capillary paths of rain and/or condensed humidity. Equally
important are checks of windshield seals and drain holes
in the bottom skin between the fuselage formers.
Testing: Evaluating an installation to ensure that every
aspect of the system performs
according to the manufacture's
specifications is essential. "It is
not uncommon to find some stuff
that's marginal, especially on an
old airplane," Riese said. Recalling
a recent Avidyne IFD540 installation, its nav signals were weak; the
culprit was the old RG58 coax that
connected the nav antenna.
Documentation
Wire: When it comes to avionics
and warranty
noise problems, most of them can
Beyond the regulatory requirebe traced to the electrical conduits
ments, documentation reunites the
that connect digital components.
two categories of craftsmanship and
"The wiring is acceptable and
gives repair shops an opportunity to
pinned out pin to pin," said Hill, but
share its notes of quality with a cus
custhe installer didn't use the "manutomer when the project is complete.
facturer specified shielded cable
Software configuration docu
docuand twisted pairs."
ments are usually required by the
Routing shielded cables is equally
digital avionics instructions for con
conimportant, Dyk said. Cables carrytinued
airworthiness
-
part
of
the
TIM DYK, Mission Aviation Fellowship
ing power or high-power signals can
Form 337. They play a critical role
bleed interference when bundled
if a unit needs service, Hill said.
with wires carrying digital signals, which can be suscepWithout a record of the unit's configuration settings, the
tible to harmonic frequencies measured in microvolts.
troubleshooting "tech has to start from the beginning and
Connectors: Connector craftsmanship changed with
figure out how someone else configured it."
the dawning of avionics' digital era, said Dyk, "when
Weight and balance documentation reveals a shop's
we stopped soldering wires into connectors and started
attention to detail. If it removed old wiring as part of the
using barrel crimp connectors. Solder worked, but there
project, its weight should be accounted for, Hill added,
was always the problem of stray solder and wires sticking
noting a cardboard box next to a Cherokee in the Des
out." When solder wicked into stranded wires, the union
Moines hangar. In it was the start of a 15-pound rat's nest
between the two became stiff, making them more suscepof removed wires and cables. Every pound counts.
tible to breaking.
How a shop stands by its work is its final measure of
Barrel crimping is more precise, he continued. With the
craftsmanship, of being an avionics artisan. The specifcrimping tool properly set to the wire's gauge, it provides
ics of a guarantee and warranty depend on the business
a 360-degree connection between the two; with the wire
and people to give it life, according to Hill, but artisans
stripped to the designated length, the insulator abuts the
always stand by their craftsmanship. q

"THE MARK
OF A QUALITY
I NS TALLAT ION

IS THAT IT NEVER
RETURNS TO THE
SHOP UNTIL THE
OWNER DECIDES
TO UPGRADE
THE AVIONICS
CAPABILITIES."

AVIONICS NEWS

JULY

2015

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