Avionics

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  • Topic: Aircraft instruments, Rechargeable battery, Airspeed indicator
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  • Published : February 20, 2013
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CHAPTER 7

AIRCRAFT AVIONICS
INTRODUCTION

from the battery posts simply by turning the handle and
pulling the quick-disconnect unit.

Modern naval aircraft have a wide variety of
missions. The electronic equipment these aircraft carry
enables them to perform these missions. We refer to this
equipment as aviation electronics (avionics). The
purpose of this chapter is to familiarize you with the
most widely used avionics in the Navy.

LEAD-ACID BATTERY
Fundamentally, there is no difference between the
lead-acid aircraft battery and the lead-acid automobile
battery. Both have lead plates in a solution of sulfuric
acid and water (electrolyte). Both operate on the same
basic principles. The lead-acid battery consists of cells
connected in series. Each cell contains positive plates
of lead peroxide and negative plates of spongy lead.

Aircraft have two primary sources of electrical
energy. The first is the generator, which converts
mechanical energy into electrical energy. The second is
the battery, which converts chemical energy into
electrical energy. The generator is the main source and
the battery is the auxiliary source. The Aviation
Electrician's Mate (AE) rating maintains aircraft
electrical systems.

NICKEL-CADMIUM BATTERY
The nickel-cadmium battery gets its name from the
composition of its plates: nickel oxide on the positive
plate and metallic cadmium on the negative plates. The
electrolyte consists of potassium hydroxide and water.
The fundamental unit of the nickel-cadmium aircraft
storage battery is the cell. The sintered-plate

AIRCRAFT STORAGE
BATTERIES
LEARNING OBJECTIVE: Identify the
basic operating principles and safety
precautions for working around aircraft
batteries.

1
2

The aircraft storage battery provides a reserve
source of electrical power for selected electrical
systems. During normal aircraft operation, the
generator maintains the battery in a charged state.

7

3

9
5

12

Batteries can be dangerous; therefore, you need to
use extreme care when working around them. Maintain
the batteries in perfect condition. Batteries are the
emergency power source for the aircraft. Do not use the
batteries for starting engines or servicing equipment if
another source of power is available. Unnecessary
usage will shorten the battery life and decrease the
power available for emergency operation. Batteries also
require a great deal of care because of the unusual
conditions under which they operate. Therefore,
batteries are usually shielded by enclosing them in a
grounded, metal-covered housing, as shown in figure
7-1.

6

8
4
10
11

ANF0701

1.
2.
3.
4.
5.
6.

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Metal cover
Fillercap and vent plug
Cell connectors
Metal container
Vent
Quick-disconnect
receptacle and plug
7. Vent

Most aircraft batteries use a quick-disconnect
receptacle and plug, as shown in figure 7-1. This unit is
a heavy-duty connector with a handle attached to a
threaded post. You can disconnect the battery cables

14

8.
9.
10.
11.
12.
13.
14.

Cell container
Positive plate group strap
Plate
Plate supports
Negative plate group strap
Separators
Cells

Figure 7-1.—Typical aircraft lead-acid storage battery.

7-1

nickel-cadmium cells used in the battery consist of two
basic types–vented and sealed cells. Most naval aircraft
nickel-cadmium storage batteries employ rectangular
vented-type cells. Sealed cells have limited
applications and come in both the rectangular and
cylindrical types.

the battery with low-velocity water fog. This
will lower the battery temperature.
WARNING
CO2 is a good fire-extinguishing agent once a
fire has started. Never spray CO2 from a portable fire
extinguisher into a battery compartment for cooling
or to displace explosive gases. The static electricity
generated by the discharge of the extinguisher could
explode the gases trapped in the battery
compartment.

BATTERY...
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