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Systems - Central Warning Display (CWD)

Nov 1, 2020

The idea behind the Turbolet’s annunciator panels is that in normal flight conditions all annunciators should be OFF - so when you see something, you know for sure something is up! The colour or each light signal has it’s own importance level:

Let L-410 Turbolet - Central Warning Display (CWD)

Left and Right Engine annunciator panels (1,4)

Let L-410 Turbolet - Central Warning Display (CWD)

Light SignalIndicated State
FIREIlluminates when any of the three sensor circuits detects an abnormal high temperature in the respective engine nacelle. Accompanied by fire bell alarm.
OIL PRESSUREOil pressure is less than 1.2kp/cm2 (17.1 psi)
FUEL PRESSUREFuel pressure is less than 0.3kp/cm2 (4.27 psi)
MINIMUM FUELFuel in relevant main tank is less than 108kg ±5kg (238 ± 11lb)
IELU INTERVENTThe engine fuel flow has been reduced in response to the IELU.
CHIPSMetal chips have been detected on the magnetic chip detector(s).
ISOLATION VALVEAutomatic or manual feathering of failed engine (torque dropped below 18%, refer technical description), or: Isolation Valve has been manually switched ON.
FUEL BYPASSThe fuel filter has been blocked and is currently in by-pass mode.
BETA RANGEThe propeller pitch is below the hydraulic low pitch stop (flight idle minimum)
IELUThe Integrated Electronic Limiter Unit is switched OFF manually, or automatically following a failure of the other engine.
AUTO FEATHERAuto-Feather system is armed, with Power Control Lever set to more than 88% or NG more than 92%.
FEATHER PUMPPropeller Feather Pump is running.
HYDRAUL.The temperature of the hydraulic fluid is higher than 85°C.
PROPELLER DE-ICINGFailure detected of the Propeller De-Ice system, including contacts.
SEPARATOR VANEWhile the Separator Vane is opening or closing, the annunciator will flash green, upon reaching open will illuminate steady green, and OFF when closed.

Airframe annunciator panel (2)

Let L-410 Turbolet - Central Warning Display (CWD)

Light SignalIndicated State
FUEL CROSSFEEDFuel crossfeed valve is open.
AUT BANK CONTROLAutomatic Bank Control Circuit is armed.
AUT BANK CONTROLAutomatic extension of an Automatic Bank Control Tab
SPOILERSSpoilers are deployed.
FUEL TRANSFERFuel transfer from the Left Tip Tank to the Left Main Tank is active.
FUEL TRANSFERFuel transfer from the Right Tip Tank to the Right Main Tank is active.
STALLINGAirspeed ±14 km/h (±8 KIAS) above stalling.
DOORMain entry, one of the three emergency exits, or one of the nose baggage doors are not locked properly.
ACTUATE TRANSFERFuel in Left Main Tank is down to 220kg (with fuel in Tip Tank), but fuel transfer has not been selected, or: fuel transfer from Tip Tank failed.
ACTUATE TRANSFERFuel in Right Main Tank is down to 220kg (with fuel in Tip Tank), but fuel transfer has not been selected, or: fuel transfer from Tip Tank failed.
SEARCH LIGHTSSearch Lights switched ON.
EXTEND LAND. GEARFlaps extended (18° or 42°) with Landing Gear retracted, both engines IDLE, Landing Gear retracted and speed below 205 km/h (111 KIAS). Continuous horn that cannot be silenced.
ENGINE STARTINGStarter-Generator in START mode, should remain ON for 20 secs, if more than 20 secs it indicates a fault.
WATER INJECTIONOperating pressure in the Water Injection System.
BAG COMP. FIRESmoke detected in the Front Baggage Compartment.
CABIN CALLSomeone in the back wants your attention :)

Electro annunciator panel (3)

Let L-410 Turbolet - Central Warning Display (CWD)

Light SignalIndicated State
INVERTER I 36V ACLoss of voltage from the #1 36V AC Inverter.
INVERTER II 36V ACLoss of voltage from the #2 36V AC Inverter.
INVERTER I 115V ACLoss of voltage from #1 115V AC Inverter.
INVERTER II 115V ACLoss of voltage from #2 115V AC Inverter.
DC GENERATORLoss of voltage from the L/H DC Generator
DC GENERATORLoss of voltage from the R/H DC Generator
AC GENERATORLoss of voltage from the L/H AC Generator.
AC GENERATORLoss of voltage from the R/H AC Generator.
MANUAL STEERINGNose Wheel Steering in MANUAL Mode.
18° FLAPSWing Flaps not 18° on ground (either 0° or 42°).
ICINGRotary Ice Detector detected ice.
EXT POWER SUPPLYExternal electrical power is connected to the aircraft’s main DC busses.
PEDAL STEERINGNose Wheel Steering in PEDAL Mode.
L/H BRAKE RELEASEDAntiskid System released L/H Brake Pressure.
R/H BRAKE RELEASEDAntiskid System released R/H Brake Pressure.
BATTERYOne or both of the Batteries are disconnected.

To sum up: when you see something on the CWD - it needs your attention and you have to act. If it’s an in-flight red warning (eg.: STALL, DOORS) it means a serious issue, so you have to act fast to prevent a catastrophic event. Train your eye where to look for each level of importance and make sure you understand them in the shortest time, so you can act fast!

In the next chapter we go through the engine, and it’s limitations.


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