AIRCRAFT ELECTRICAL SYSTEMS
DESCRIPTION AND TYPES
As an Aviation Electrician (AE), you will work
with many electrical systems. You must be a
OF LAMPS
well-rounded aviation technician. You may work
Aircraft lamps are devices that provide sources
directly or indirectly with all other aviation
maintenance ratings. You may work with Avia-
of artificial light. The incandescent light is the
most common type. It uses an electrical source
tion Machinist Mates (ADs) on power plant
to heat a filament until it is white hot. Normally,
discrepancies, or with Aviation Structural
the source voltage is 26 to 28 volts ac or dc.
Mechanics (AMs) on electrohydraulic malfunc-
tions.
However, some lighting systems use lower voltage
In this chapter, you will learn about various
lamps and step-down transformers to supply 3 to
systems that AEs regularly maintain. Maintaining
6 volts to the lamps. The lower operating voltage
naval aircraft systems is the number one priority;
allows the lamp filament to be larger, and it helps
to reduce lamp failure due to vibrations.
teamwork and maximum effort will pay dividends
When a lamp fails, the replacement must be
in flight safety and mission accomplishment.
the same as the original lamp or an approved
alternate. Spare lamps in the aircraft are shock-
mounted. If they weren't, they would probably
AIRCRAFT LIGHTING SYSTEMS
fail earlier than the original lamps because cold
filaments are subject to fatigue failure sooner than
hot ones. You need to be sure that the glass bulb
Learning Objective: Recognize operating
principles and construction features of
of the lamp is clear and free from grease and dirt.
To help keep bulbs clean, don't touch the glass
aircraft lighting, b o t h internal and
bulb with your bare hands, if possible.
external, and identify types of lamps used
The parts of a lamp are the bulb, filament,
in these circuits.
and base. Incandescent lamps vary chiefly in
The lighting system in an aircraft serves two
electrical rating, base type, bulb shape, and bulb
finish.
primary purposes--it provides specialized light
The electrical rating of lamps is expressed as
sources outside the aircraft and illuminates the
a combination of volts, watts, amperes, and
interior. Exterior lights provide illumination at
candlepower. (Candlepower is the luminous
night for navigation and formation flying. Other
intensity expressed in candles and used to specify
exterior light operations include, signaling,
the strength of a light source.) The lamp rating
landing, and anticollision. The interior lighting
is found on either the base or the bulb of the lamp.
provides illumination for instruments, equipment,
On small lamps, an identifying number represents
cockpits, and cabins. In addition, the electrical,
the electrical rating. This number is the same as
electronic, and mechanical systems use lights
the military specification (MS) dash number. You
to indicate normal operation or a possible
can find it on the lamp base.
malfunction. Lights also show the position of the
The base types vary as to size, number of
landing gear, bomb bay doors, sonobuoy exit
electrical contacts, and the method of securing in
doors, etc.
Various types and sizes of light assemblies are
a socket. The most common types of bases are
used on present-day naval aircraft. The lighting
the single- or double-contact bayonet (push in and
turn). These bases are used on aircraft since they
requirement governs the selection of a particular
lock in the socket and do not loosen because of
light assembly. Most light assemblies consists of
vibration. Single contact bases are used in
a housing (fixture), a lamp, and a lens.
