VR Avionics Walter M601 - Initiating a Run

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TSLM - M601 Operational & Install Manual

If one of the pre-start checks failed, you should correct the cause before trying again. To

acknowledge or reset the error code on the TSLM light you can press the START or RUN button

for 1 second. The TSLM light shall stop flashing and you are ready to issue another start.

If all the pre-start checks pass, the TSLM will activate the start sequence by engaging the starter,

turning on the ignition and sequencing the fuel to the torch igniters. You should be able to hear the

starter/generator wind up and the igniters producing sparks. From the moment the starter engages

there are 10 seconds reserved for light-off. Light-off is where the main fuel in the combustion

chamber ignites and can clearly be heard and seen in the ITT rising sharply. In case light-off does

not occur within the 10 seconds (which implies some problem), the TSLM will turn off the ignition

and stop the fuel to the torch igniters, but continue spinning the engine for 10 more seconds.

If this happens the pilot must close the fuel (shut-off valve lever to closed) just after the first 10

second period have expired. With the engine spinning for the next 10 seconds or so, closing the

fuel will purge fuel vapors from the combustion chamber.

If the engine lights off before the first 10 second period expired (as would normally happen), the

TSLM will sense this and immediately start controlling the rise in ITT and the absolute ITT value as

needed by activating the EHT valve. Both the TSLM light and the EHT light (if fitted) will turn on

when the EHT is activated by the TSLM during the start.

If the ITT leads (from the thermocouples) is connected the wrong way around (maybe after a

service) or become disconnected in some way that would only become apparent after light-off, the

TSLM will sense this and immediately turn on the EXCEED light. Since the TSLM can no longer

measure the ITT accurately in this condition, the pilot needs to abort the start by cutting fuel as

earlier mentioned to avoid possibly damaging the turbine. The starter will remain active for another

10 seconds so that fuel can again be purged from the combustion chamber.

The EXCEED light will also be turned on when the ITT increases to over 700ºC. The TSLM should

be able to control the ITT to below this temperature. If it is unable to, this would imply some major

problem – for example unintended isolating valve activation, dead batteries, or fuel control unit

problems. An abort of the start is recommended in this case.

When the compressor reaches idle speed (above 50%), the starter, ignition and fuel to the torch

igniters will be turned off. Otherwise these devices will timeout 20 seconds after light-off was

detected.