to the main transmission gearbox through a coax-
helicopters. Multi-rotor helicopters are classified
into different categories according to their rotor
ial main drive shaft. The main drive on the shaft
is on the rear of the T58 and on the front of the
configuration. Two different types are the coaxial
T700 engines. See figures 7-6 and 7-7.
rotor and tandem rotor.
The single-rotor configuration requires the use
of a vertical tail rotor to counteract torque and
NOTE: The T700-GE-401 turboshaft
provide directional control. The advantages of
engine is one of a new generation of
aviation propulsion systems with modular
this configuration are simplicity in design and
construction. Modular construction allows
effective directional control. Coaxial rotors are
intermediate maintenance activities to
two rotors mounted on the same mast and turning
replace major engine components, such as
in opposite directions. The torque produced by
the two rotors balance each other out. Coaxial
turbine sections, with basic hand tools. The
rotor systems have good ground clearance and are
ability to replace parts at the lowest level
of maintenance (third-degree intermediate)
easy to maneuver. Their arrangement and controls
increases aircraft availability by decreas-
are more complicated then single rotor systems.
ing down time.
In the tandem rotor design, one rotor is located
forward and the other located aft. Sometimes the
THE T58-GE-10 TURBOSHAFT ENGINE
rotor blades are in the same plane. The blades may
or may not intermesh. The design offers good
The T58-GE-10 engine is a compact turboshaft
longitudinal stability since the fuselage hangs at
two points, fore and aft. Like the coaxial rotor,
engine with high power-to-weight ratio. The T58
engine consists of two basic sections. These sec-
the tandem rotor has little torque to overcome
tions are the gas generator and the power turbine
since these rotors rotate in opposite directions.
Most of the Navy helicopters are a twin-
sections.
turbine engine powered, single rotor design like
the SH-60 and SH-3. Some small trainer
Gas Generator Section
helicopters like the TH-57 have only one engine,
The gas generator section is divided into five
and large helicopters like the CH-53 Super Stallion
subsections. These subsections are the front
have three turbine engines. The maintenance
frame, accessories, compressor, combustion, and
procedures and examples of components used are
gas generator turbine.
those of the representative SH-60 and SH-3
helicopters. Both types are used to compare
FRONT FRAME.-- The front frame provides
similarities and differences between a modular and
provisions for engine mounting and supports the
nonmodular design.
accessory section. It provides for engine air inlet
and anti-icing for the inlet air.
NOTE: While procedures for specific
engines or aircraft are included, many
ACCESSORY SECTION.-- The accessory
pertinent or mandatory references are left
section consists of the centrifugal fuel purifier,
out. For this reason always refer to the
accessory drive gear casing assembly, lube-
applicable maintenance instruction
manuals.
scavenge pump, fuel pump, main fuel control, and
the pilot valve. It mounts to the bottom of the
front frame section and extends under the
compressor section. Power to drive the accessory
HELICOPTER POWER PLANTS
section is received from the gas generator rotor.
The SH-3 uses two T58-GE-10 turboshaft
engines. The SH-60 uses two T700-GE-401
COMPRESSOR SECTION.-- The compres-
sor is a 10-stage axial flow unit that consists of
turboshaft engines. See figures 7-6 and 7-7.
a rotor and a stator. The inlet guide vanes and
Both of these turboshaft engines use the free
the vanes in stages 1 through 3 are automatically
turbine principle for power takeoff to the main
positioned by the stator vane actuator using fuel
transmission gearbox. Power takeoff comes from
pressure for the motive force.
the power turbine section. This section is
mechanically independent from the gas generator.
COMBUSTION SECTION.-- The combus-
Exhaust gases from the gas generator turbine drive
tion section is a singular annular type of unit. It
the power turbine. The power turbine is connected
7-8
