CHAPTER 1
AIRCRAFT CONSTRUCTION AND MATERIALS
Chapter Objective: Upon completion of this chapter, you will have a basic working
knowledge of aircraft construction, structural stress, and materials used on both
fixed- and rotary-wing airfraft.
One of the requirements of an Aviation Structural
Mechanic is to be familiar with the various terms related
to aircraft construction. Aircraft maintenance is the
primary responsibility of the Aviation Structural
Mechanic H (AMH) and Aviation Structural Mechanic
S (AMS) ratings. Therefore, you should be familiar with
the principal aircraft structural units and flight control
systems of fixed and rotary-wing aircraft. While the
maintenance of the airframe is primarily the respon-
sibility of the AMS rating, the information presented in
this chapter also applies to the AMH rating. The
purpose, locations, and construction features of each
unit are described in this chapter.
Each naval aircraft is built to meet certain specified
requirements. These requirements must be selected in
such a way that they can be built into one machine. It is
not possible for one aircraft to have all characteristics.
The type and class of an aircraft determine how strong
it will be built. A Navy fighter, for example, must be
fast, maneuverable, and equipped for both attack and
defense. To meet these requirements, the aircraft is
highly powered and has a very strong structure.
The airframe of a fixed-wing aircraft consists of five
principal units. These units include the fuselage, wings,
stabilizers, flight control surfaces, and landing gear. A
rotary-wing aircraft consists of the fuselage, landing
gear, main rotor assembly, and tail rotor. A further
breakdown of these units is made in this chapter. This
chapter also describes the purpose, location, and
construction features of each unit.
FIXED-WING AIRCRAFT
Learning Objective: Identify the principal
structural units of fixed-wing and rotary-wing
aircraft.
There are nine principal structural units of a
fixed-wing (conventional) aircraft: the fuselage, engine
mount, nacelle, wings, stabilizers, flight control
surfaces, landing gear, arresting gear, and catapult
equipment.
FUSELAGE
The fuselage is the main structure or body of the
aircraft to which all other units attach. It provides spare
for the crew, passengers, cargo, most of the accessories,
and other equipment.
Fuselages of naval aircraft have much in common
from the standpoint of construction and design. They
vary mainly in size and arrangement of the different
compartments. Designs vary with the manufacturers
and the requirements for the types of service the aircraft
must perform.
The fuselage of most naval aircraft are of all-metal
construction assembled in a modification of the
monocoque design. The monocoque design relies
largely on the strength of the skin or shell (covering) to
carry the various loads. This design may be divided into
three classes: monocoque, semimonocoque, and re-
inforced shell, and different portions of the same
fuselage may belong to any of these classes. The
monocoque has its only reinforcement vertical rings,
station webs, and bulkheads. In the semimonocoque
design, in addition to these the skin is reinforced by
longitudinal members, that is, stringers and longerons,
but has no diagonal web members. The reinforced shell
has the shell reinforced by a complete framework of
structural members. The cross sectional shape is derived
from bulkheads, station webs, and rings. The longi-
tudinal contour is developed with longerons, formers,
and stringers. The skin (covering) which is fastened to
all these members carries primarily the shear load and,
together with the longitudinal members, the loads of
tension and bending stresses. Station webs are built up
assemblies located at intervals to carry concentrated
loads and at points where fittings are used to attach
external parts such as wings alighting gear, and engine
mounts. Formers and stringers may be single pieces of
built-up sections.
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