Avionics News July 2015 - 30

MORE POWER TO THE PANEL
Continued from page 28

the total the aircraft's alternator/generator can deliver, what
do you do now?
Not many customers would want to cut back on the
equipment in their panel, and as someone whose business
is selling and installing avionics, you don't want to go that
route. So the only alternative is to get more power to the
panel in the form of a new, higher-output alternator.
Of course, installing a new, more powerful alternator in
a certificated airplane is a serious bit of work. In addition
to having to make a significant number of changes to
the aircraft's electrical system, it will require FAA field
approval. So it's not something you just jump into.
If you have questions, Quave said that shops can go to
Hartzell Engine Technologies' website and contact them for
particular guidance with an alternator issue or upgrade.
Generators are so Old-Gen
Another challenge many shops find when doing an avionics
upgrade is that the aircraft is still equipped with a legacy
DC generator. Not that there's anything wrong with
generators in many installations, it's just that they have
some performance drawbacks when compared to newer
alternators.
* Alternators have higher power densities than DC
generators.
* Alternator systems generally weigh considerably less
than a DC generator system.
* Alternators are essentially self-limiting, which is
very good for today's avionics.
* Alternators also are less noisy, electronically
speaking, due to their lack of a commutation system.
* Alternators deliver consistent power at lower engine
RPMs than generators.
* Alternators are more reliable and require less
maintenance.
"If the aircraft has a legacy DC generator, there are some
definite advantages to convert to a new alternator," Quave
said. "It is clearly a better solution for today's avionics.
And with all the STCs and kits available for generator-toalternator conversion, it's a pretty simple process for any
shop."
Alternator Rx
While alternators do offer a host of advantages over
legacy DC generators, they're not immune to problems.
After years of making and repairing tens of thousands of
alternators, Quave and the team at Hartzell know a bit about
what problems they can have.
"If properly suited for their installation, an alternator will
30

AVIONICS NEWS

JULY

2015

typically have a very long, trouble-free service life," Quave
said. "But when they have issues, the most common failure
mode is an open rotor condition that can often be attributed
to field-winding conditions. The second most common
failure is the rectifier diodes due to overheating."
Speaking of temperature, the weather can have an impact
on the performance of an alternator. Especially in cold
weather, the rotating components in the alternator can suffer
the same issues as a piston engine.
Also, cold, thick bearing grease will decrease the
unit's efficiency during the initial engine start. Freezing
temperatures can cause belts to lose their elasticity, which
leads to slippage on the pulley drive - again, reducing the
unit's ability to produce full power ratings.
While it's difficult to know whether your alternator is
having health issues just by looking at it, there are some
signs that things are not going well inside the case.
"When you start to hear background noise in the
aircraft's audio system, it's often a sign that there's a
problem with the alternator or magneto system," Ingle
said. "Noise from the magnetos or alternator will vary
in frequency with changes in engine RPM. A common
troubleshooting method is to perform a mag check and/
or turn off the alternator. One of the disabled systems may
eliminate the interference."
If you try those easy tests and the noise persists, then it's
time for a new alternator.
New-generation alternators
While Hartzell Engine Technologies holds FAA parts
manufacturer approval and continues to manufacture
modern, direct replacements for most legacy Prestolite,
Ford and Chrysler alternators, it, along with other
manufacturers, has introduced a variety of new-generation
12- and 24-volt alternators.
Dollar for dollar, these updated units offer a number of
significant advancements over older models. And more
importantly, these new alternators are designed to meet the
needs of today's aircraft.
For example, HET's new-generation ALV-9610
(Continental gear driven) and ES-Series (Lycoming
and Continental belt driven) are direct replacements for
legacy alternators. The new models are up to 9.6 pounds
lighter than the original units (depending on model and
installation), and, more importantly, they provide greater
power output at cruise settings, making it ideal for 24-volt
aircraft with glass displays.
In addition, many models offer built-in noise filtering,
which eliminates alternator-induced static interference.
The bottom line is this: If your customer's installation
budget can stand it, you might want to include a new
alternator as part of your next panel upgrade package. q

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