Avionics News March 2015 - 36

AVIONICS CORROSION CONTROL
Continued from page 34

Pins and connectors are good places to start your search,
but they're not the only places where corrosion breeds.
"While it depends totally on the aircraft and situation, we
often see corrosion attacking dissimilar metals, especially
around antenna installations," Haskell said. "Technicians
will use an incorrect type of screw and nut plate, and that can
cause corrosion to get in between the bonding and the antenna. Something as simple as using the correct type of screw
can prevent these types of problems from occurring. Another
place to look is behind the instrument panel. That's a hard
place to access, and it rarely gets inspected. That's important,
especially on aircraft based in hot, humid environments."

Corrosion clean up

Let's say we've found some corrosion on a connector.
What do we do about it?
"You cannot be too aggressive when dealing with corrosion repairs on avionics," Pearson said. "A metal grinder is
not going to be your tool of choice. It's more likely going to
be something like a pencil eraser. There's a bit of abrasive
embedded in the eraser, and that works well in small areas.

No doubt, there are higher-tech versions of that idea.
"I've also seen technicians use a little baking soda and a
small brush to clean corrosion byproducts off of boards and
connectors. Afterward, you must thoroughly rinse the area
with distilled water, and then use something like 99 percent
isopropyl alcohol solution to get the water out."
Once all the corrosion is removed, you can dry the unit
and return it to service or apply a thick coating of a CPC
to protect the component and help prevent corrosion from
returning.
Keep in mind that once an area has been damaged by corrosion, it will be that much more prone for the problem to
return. As they say, "An ounce of prevention ..."

Corrosion's silver lining

While you wouldn't wish corrosion damage on anyone,
there is a bit of a silver lining to the problem, such as offering
complete avionics, or whole aircraft for that matter, corrosion
treatment services to your customers.
It could be a nice bit of added income for your avionics
repair shop. The upfront investment is rather small. There's
not a lot of training required for your technicians - almost
zero liability. It's something that can benefit your customers'
aircraft. What more could you want? q

Routinely inspect all plugs, pins and connectors for signs of corrosion and contaminant buildups.

Use an approved cleaner, and follow the manufacturer's instructions for application and removal of all
materials.

Always have clean plastic bags and/or plastic connector caps ready when removing avionics from an
airplane, and never remove avionics from an airplane on the ramp in the rain.

When storing avionics prior to reinstallation, always keep the units covered and stored in a humiditycontrolled room. If the avionics will be in the shop or on the bench for an extended period of time,
make sure to cover them nightly with plastic to keep contaminants out of the boxes.

Carefully inspect all rubber seals on avionics access doors that open to the exterior of the aircraft for
cracks and splits that can allow water penetration. This is especially important for nose- and radomemounted systems.

When dealing with avionics that have forced air-cooling, inspect the vents and inside the boxes for
contaminant buildup. Follow the manufacturer's guidelines to clean any materials from the boards.

Frequently inspect all antenna mounts and connectors where they connect at the airframe. These
areas are highly prone to corrosion and require extra attention.

If you decide to apply an approved corrosion prevention compound, follow the manufacturer's
guidelines. A little goes a long way, and overapplication will only lead to additional cleanup.

TOOLBOX
TIPS FOR
AVIONICS
CORROSION
CONTROL

Make proactive corrosion inspection a part of your standard avionics services processes.

10. If you ever have a question about how to handle any unusual corrosion situations, contact the unit's
OEM immediately. An unapproved repair can cause more damage than the corrosion itself. q
36

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Avionics News March 2015

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