VENTILATION – LIMITATIONS
Refer to AW139-RFM-4D Section 1.
HEATING SYSTEM – GENERAL
The purpose of the heating system is to supply warm air to the cockpit and
cabin to maintain a comfortable environment and to defrost windshields and
lower windows.
The heating system supplies cockpit and cabin with a mix of hot pressurized
air bled from the compressor discharge port (P3) of both engines and
external air sucked in through an air inlet on the LH aft fuselage.
Two solenoid controlled bleed air shut-off valves (SOV) control the relevant
engine hot pressurized air to supply the heating system when selected on by
the pilot and the engine operates normally.
The bleed air SOV are automatically closed if any of the following occurs:
• a failure in the heating system is detected
• engine is not running
• fire extinguishing system is armed (see Ch.26-00-00)
• loss of electrical control signal
The engine hot pressurized air is routed to the Temperature Control Valve
(TCV) which controls the quantity of hot air to be mixed with outside fresh air
sucked in by a jet pump. The mixing occurs in the jet pump.
The mixed air enters the cabin and the cockpit via the air distribution ducts.
The right and left diffusers are located on the floor area. They provide the
distribution of the heated air through the cabin (passenger area). The
distribution ducts are connected to the cockpit ventilation system and they
are also dedicated to the pilots.
The airflow temperature is automatically controlled by the Heating Control
Box (HCB) through the TEMP CONTR knob on the COND/HEATER control
panel when the COND/HTR selector is set at AUTO.
In case of failure of the automatic temperature control, the pilot can manually
control the position of the TCV by setting the COND/HTR selector to MAN
and using the TEMP CONTR knob as a trim switch in the positions.