Revision - MD Helicopters MD Explorer Servicing And Maintenance

3. Helicopter Description
(Ref. Figure 1)
The MD Explorer helicopter is a turbine
powered, rotary wing aircraft made primarily
of advanced composite materials. The rotor
has five blades. The anti-torque system is a
NOTARR anti-torque system. Engine output
is supplied to the rotor and anti-torque system
by drive shafts and a transmission. One way
overrunning clutches between the engines and
transmission permits the rotor to freewheel for
auto rotational descent.
The fuselage is a semimonocoque construction
divided into three sections. The sections are
the crew, passenger and baggage compart­
ments. The basic fuselage structure consists of
the sub-structure, mast support structure and
an A-Frame.
The crew compartment is assembled with
seats for the pilot and one passenger. The crew
compartment right seat is the pilot's seat. The
passenger compartment is directly aft of the
crew compartment and contains provisions for
folding passenger seats. Passenger seats can
be folded out of the way or completely removed
to accommodate cargo.
The aft section of the fuselage is the baggage
compartment and includes structure for tail
boom attachment and the NOTARR fan
assembly.
The tail boom assembly is a monocoque
construction of carbon fiber composites. The
tail boom is the supporting structure for the
diverter plate, horizontal stabilizer, direct jet
thruster and control cables.
A. Major Components
The MD Explorer consists of the following
major components.
Airframe - The airframe consists of the
fuselage, tailboom, empennage, and landing
gear. The fuselage includes the rotor support
and landing gear structures. The fuselage,
tailboom and empennage are a hybrid
construction consisting of metallic and
composite components. The composite materi­
als used are 350 °F (176.67 °C) cure graphite/
epoxy and fiberglass/epoxy with Nomex
honeycomb used, as required.
MD Helicopters, Inc.
Rotorcraft Maintenance Manual
The landing gear is a horizontal skid-type
gear and is not retractable. It consists of two
skid tubes, two crosstubes, and a pair of
hydraulic dampers that connect the tips of the
aft crosstube to the aft ends of the skids. The
crosstubes clamp into saddles in the bottom of
the fuselage. The skids are bent upward at the
front to minimize digging into soft ground in a
nose-down run-on landing and to serve as a
step for entering the cockpit. Three hard-sur­
faced anti-wear pads are placed on the bottom
of each skid in line with the crosstubes for
protection during landings on abrasive
surfaces.
Powerplant - The powerplant is a Pratt &
Whitney PW206A, PW206E, or PW207E
engine and the associated electrical, oil
cooling, and powerplant control and monitor­
ing subsystems.
The Pratt & Whitney powerplant is a light­
weight, free turbine, turboshaft engine. It
incorporates a single stage centrifugal
compressor, driven by a single stage turbine.
Metered fuel is sprayed into a reverse flow
annular combustion chamber through fuel
nozzles mounted around the gas generator
case. A high voltage ignition unit and dual
spark ignitors are used to start combustion.
A single channel Full Authority Digital
Electronic Control (FADEC) system ensures
accurate control of the engine output speed
during normal operations. An electrical
stepper motor located within the Fuel Meter­
ing Unit (FMU) works in conjunction with the
Electronic Engine Control (EEC) to control and
monitor engine performance. A mechanical
throttle control overrides the FADEC system
to provide pilot control of the engine output
speed during abnormal or emergency condi­
tions.
Fuel System - The fuel system consists of
fuel storage, distribution and vent sub-sys­
tems. The fuel system provides maximum
safety by isolating and sealing the fuel
sources. The fuel system is designed so that no
single failure can result in fuel starvation.
PW206A/E CONFIG Lines and valves from
the fuel cell to engine deck are shrouded and
tied to an overboard drain line. This allows for
isolation of fuel leaks from the airframe and
cabin, while draining excess fuel overboard.
01-00-00
CSP−900RMM−2
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Revision 14