HEADQUARTERS OH-58A, Technical Manual

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TM 55-1520-228-10
CHAPTER 2
HELICOPTER AND SYSTEMS DESCRIPTION
AND OPERATIONS
SECTION I. HELICOPTER
2-1. GENERAL.
The OH-58A/C helicopter ( fi gure 2-1
A
. and fi gure 2-2
C
. ) is a single engine, observation type helicopter de-
signed for landing and takeoff from prepared or unpre-
pared surfaces. The fuselage consists of the forward
section, intermediate or transition section, and the aft
or tailboom section. The forward section provides the
cabin and fuel cell enclosure as well as pylon support.
Entrance to the cabin is provided by two doors on each
side. The pilot station ( fi gure 2-3
A
. and fi gure 2-4
C
. )
is located on the right and the copilot/observer station is
located on the left side of the helicopter. The area aft of
the pilot and copilot may be used as a cargo/passen-
ger compartment. The intermediate section supports
the engine and includes the equipment and electronic
compartment. The tailboom supports the horizontal sta-
bilizer, vertical stabilizer, and tail rotor. The basic struc-
ture of the forward section consists of a lower-curved
honeycomb sandwich panel and an upper longitudinal
aluminum beam. The core of the sandwich structure is
aluminum alloy throughout. The faces are aluminum al-
loy except in the fuel cell region, where they are fi ber-
glass. The aluminum alloy sandwich panel is capable of
withstanding the speci fi ed design cargo loadings, while
the fi berglass sandwich supports the fuel cell pressures.
The rotor, transmission, and engine are supported by
the upper longitudinal beam. The upper and lower struc-
tures are interconnected by three fuselage bulkheads
and a centerpost to form an integrated structure. The
most forward and aft bulkheads act as carry-through
structure for the skid landing gear crosstubes. The tail-
boom is a monocoque structure with aluminum skin and
aluminum substructure.
a. Dimensions. Principal dimensions of the heli-
copter areas are shown in fi gure 2-5.
b. Turning Radius and Ground Clearance. (Refer
to fi gure 2-6.)
c. Weights. The helicopter weight empty and gross
operating weight will change according to the con fi gu-
ration or equipment installed for the type of mission to
be performed. Refer to Chapter 6, Weight/Balance and
Loading.
d. Crew Con fi guration. The crew consists of the
pilot alone, pilot and copilot, or pilot and observer.
2-2. PASSIVE DEFENSE.
The armor protection is a combination of ceramic and
fi berglass composite with a small amount of dual hard-
ness steel. The armor protection is removable.
Crew Protection. Armor protection is furnished for
the pilot and copilot and consists of panels on seat bot-
tom, seat back, and outboard side of each seat.
2-3. LANDING GEAR SYSTEM.
a. Standard System. The landing gear system is
a skid type, consisting of two laterally mounted arched
crosstubes, attached to two formed longitudinal skid
tubes. Then landing gear structure members are made
from formed aluminum alloy tubing with steel skid shoes
to minimize skid wear. The gear assembly is attached
with straps/clamps at four points to the fuselage struc-
ture, therefore, gear removal for maintenance can easily
be accomplished. The manually retractable and quickly
removable wheel assemblies have been provided to
facilitate helicopter ground handling operations.
b. High Skid Gear. The high skid gear, when in-
stalled, will provide an approximate additional 14 inches
of ground clearance. This will improve landings to be
accomplished in snow and rough terrain areas.
Change 14 2-1