DA 42 NG AFM	Airplane Description

7.9.6 COOLING SYSTEM

Each engine is liquid cooled. The liquid cooling system consists of a radiator (coolant heat exchange) and a bypass to this radiator. The bypass is in operation when coolant temperatures are low. It therefore allows the engine to warm-up quickly. Upon reaching a certain temperature (approximately 88 °C or 190 °F) the radiator is activated by a thermostat valve. Additionally a coolant to air heat exchanger is provided for the cabin heat system. The flow through the heat exchanger is independent of the coolant temperature. An expansion tank helps to adjust the pressure in the system. The system is protected against overpressure by means of a pressure relief valve.

Pressure Relief Valve

Expansion

Tank

Thermostatic Valve

Core

Engine

Water Pump

Coolant

Heat

Exchanger

Cabin

Heater

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Airplane Description	DA 42 NG AFM

7.9.7 OIL SYSTEMS

Each engine has two separate oil systems.

Lubrication System (Engine and Turbo-Charger)

The engine lubrication is a wet sump lubrication system. The oil is cooled by a water/oil-cooler on the upperside of the engine.

A dip-stick is provided to check the oil quantity through an inspection hole in the left cowling. If required, oil can also be filled in there (for approved oil grades refer to Section 2.4 - POWER-PLANT LIMITATIONS).

Gearbox and Propeller Governor System

The second oil circuit lubricates the gearbox and serves the governor system and the regulation of the propeller.

The gearbox oil quantity can be checked with the help of an inspection glass which can be reached through an inspection hole on the left side of the cowling.

CAUTION

If the gearbox oil quantity is too low, an unscheduled maintenance is necessary (for approved oil grades refer to

Section 2.4 - POWER-PLANT LIMITATIONS).

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DA 42 NG AFM	Airplane Description

7.9.8 TURBO-CHARGER SYSTEM

	engine
	air inlet
intercooler	filter box
turbine	air filter
engine	alternate air valve
	charger
waste gate	alternate air inlet
	exhaust

The exhaust system contains a manifold which collects exhaust gases from the outlets of the cylinders and feeds them to the turbine of the turbo charger. Behind the turbine the exhaust gases are guided through the lower cowling to the exterior of the airplane. Excess exhaust gases bypass the turbine. The bypass is controlled by the ECU through the waste gate valve. A manifold pressure sensor behind the compressor allows the ECU to calculate the correct position of the waste gate valve. This prevents excessive manifold pressures at low density altitudes. The intake air is compressed in the compressor which is driven by the turbine, and is subsequently cooled down in the intercooler to increase power. Cooling the air increases efficiency through the higher density of the cooler air.

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Airplane Description	DA 42 NG AFM

7.9.9 FIRE DETECTION SYSTEM

The fire detection system in the DA 42 NG consists of an overheat detector in the hot area of each engine. In case of an increase of the engine compartment temperature above 250 °C (480 °F) the overheat detector closes the electric circuit and a warning message appears in the annunciation window of the G1000 PFD.

To test the fire detectors (refer to Section 4A.6.1 - PREFLIGHT INSPECTION) push the test button located next to the gear selector switch. An aural alert and the fire warning message for the LH and RH engine should appear in the annunciation window of the

G1000 PFD.

CAUTION

If the aural alert or the warning does not appear, an unscheduled maintenance is necessary.

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