Description And Operation; Vent System; Vent System Components; Inlet Duct - MD Helicopters MD Explorer Servicing And Maintenance

1. Vent System

The vent system introduces outside air into
the cabin and crew compartment. Air enters
through an air inlet duct above the transmis­
sion deck. Air is routed into a water separator
to remove moisture (rain), while maintaining a
constant air flow. A two speed vent fan, located
on the transmission deck is used to induce
airflow. Air enters the cockpit and cabin area
through a plenum, air ducts and gasper
assemblies.

2. Vent System Components

A. Inlet Duct
An inlet duct is attached to the right side of
the forward swashplate fairing assembly. An
inlet hole measuring five inches in diameter is
covered with an air scoop and screen to allow
outside air in for the air vent system.
B. Water Separator
The water separator is located immediately
downstream from the inlet duct. Outside air
enters the water separator. Moisture (rain)
entering the water separator with fresh air is
centrifugally extracted to the bottom of the
water separator when the air makes a 180
degree turn and flows into a vent fan. Water is
drained from the separator when a rubber
check valve opens into on the transmission
deck.
C. Vent Fan
The vent fan is used to initiate and sustain air
flow at 180 cubic feet per minute. The fan is a
two speed vane axial type with an aluminum
impeller. The fan is powered by a 28 vdc
brushless motor. The vent fan is mounted at
fuselage station 185.5 on the right side of the
transmission deck. A five position AC/VENT
MD Helicopters, Inc.
Rotorcraft Maintenance Manual
VENT SYSTEM

DESCRIPTION AND OPERATION

switch controls the vent fan and air condition­
ing. VENT LOW provides vent air at a low
setting. VENT HIGH provides air at a high
setting, selected from the center console utility
panel assembly.
D. Air Supply Plenum
The air supply plenum distributes the air flow
from the inlet duct and vent fan to the air
ducts. The air supply plenum is constructed of
composite fiberglass.
E. Air Ducts
Air ducts route air directly to the gasper
assemblies from the air supply plenum. The
air ducts are constructed of silicon rubber
coated woven fiberglass, with a nylon heli-coil
reinforcement.
F. Crew Station Gasper Assemblies
Four crew station gasper assemblies allow air
to be directed into the cockpit. The gasper
assemblies are constructed of aluminum and
are capable of delivering a flow volume of 20
cubic feet per minute. The gasper assemblies
utilize an inner cylindrical disc that allows air
to discharge at adjustable volume rates. A
finger rotation of the assembly will alternate
the gasper assembly's cylindrical disc to
change air flow discharge volume.
G. Passenger Gasper Assemblies
Passenger gasper assemblies are located at six
various locations in the passenger compart­
ment ceiling. Gasper assemblies are
constructed of aluminum and are capable of
delivering air at a flow volume of 20 cubic feet
per minute. Gasper assemblies utilize an inner
cylindrical disc to discharge air at adjustable
volume rates. A finger rotation of the assembly
will alternate the gasper assembly's cylindrical
disc to change the air flow discharge volume.
21-20-00
CSP−900RMM−2
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