228.53
Figure 4-17.—Electrochemical corrosion.
whenever batteries are used. The battery compartment
shown in figure 4-18 needs immediate attention.
WARNING
Before performing any cleaning, inspec-
tion, or maintenance on electrical systems,
maintenance personnel should make sure that
all electrical power is secured from the air-
craft. If the electrical power is NOT secured
from the aircraft, it could result in serious
injury to maintenance personnel.
Multiple Electrical Connectors (Cannon Plugs).
Connectors mounted in avionic and electrical systems
are prone to the same corrosive environment as
airframe structural components (fig. 4-19). Normally,
connectors and mounting plates contain a gasket that
acts as a watertight seal. When maintenance personnel
dismantle (take apart) a connector for cleaning or
repair, they should inspect the gasket. They should
give special attention to connectors that use
replaceable pins. These connectors use a self-sealing
gasket water seal or dog bones (plastic inserts) that
automatically seal the connectors against water
intrusion. The repeated removal and replacement of the
pins or forgetting the dog bones may cause the watertight
seal to lose its effectiveness. In extreme cases where the
connector cannot be replaced, potting compounds must
be used to prevent water intrusion. You can find the stock
numbers for dog bones in the applicable IPB.
Coaxial Connectors. Look at figure 4-20. It shows
corrosion on a coaxial connector. Coaxial connectors
require special steps to avoid water intrusion. Usually,
moisture, contaminants, and corrosion in fuel quantity,
oil quantity, and similar capacitive-type indicating
system connectors cause erroneous (wrong) quantity
indications in the cockpit indicating systems. Antenna
coaxial connectors have similar problems with moisture.
Wire Harnesses and Cables. When corrosion is
discovered at the pin-to-wire connection on electrical
connectors, plugs, and receptacles, the wire harness
4-28
