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Starts the Walter M601 engine safely & efficiently
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Activates starter, igniters & ignition-fuel valves for start and run operations
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Activates igniters & ignition-fuel valves when pilot commands anti-flameout operation
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Activates the EHT valve (limiter) to protect against:
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Start ITT exceedences - hotstarts
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Propeller overspeeds in beta-mode
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Monitors engine parameters - ITT, N1, N2, Torque, etc.
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Indicates and records all parameter exceedences
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Sends parameter information on to displays, laptops, etc.
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Records every start & run operation
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Diagnostic test trouble-shooting capable
Starting the engine safely
The TSLM contributes to safety primarily by reducing the risk of hotstarting. During a hotstart the
turbine engine internals are subjected to excessive temperature resulting in damage or degradation
to the effect that it may be the leading cause of a major engine failure sometime in the future,
with possible fatal consequences. Repairing the engine internals after a hotstart event is also very costly.
The TSLM not only controls the start to prevent any temperature exceedence, but also records every start in memory. Thus
one can always go back and see exactly what happened during a particular start.
There are however certain conditions where the TSLM will not be able to prevent a hotstart on the Walter M601 engine.
They are:
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When the pilot starts the engine in emergency ISOL mode where the engine's FCU (fuel-control unit) and thus the TSLM's fuel-derichment
control is bypassed. The TSLM will allow such a start to continue (activate the starter motor, etc.), but the pilot will have
to prevent any hotstart by controlling the condition lever.
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When the aircraft batteries does no contain sufficient energy to power the starter motor through the critical stages.
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When the ITT (inter-turbine temperature) before the start is already too high (above 200°C). A dry-run operation can be performed to
first cool down the turbine.
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When too much fuel is present inside the engine's burner can before the start. This may be the result of the
pilot performing an engine shutdown or dry-run operation improperly. This fuel has to be purged before the next start is issued
by performing a dry-run operation (with condition lever in shut-off as always).
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Before starting, the throttle must be in the prescribed flight-idle position - conforming to the engine starting procedure.
As a first line of defence the TSLM will attempt to detect some of the above conditions and decline any start that it deems unsave.
The problem will be indicated to the pilot via the TSLM STATUS light to be rectifed before attempting another start. They are:
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When the ITT (inter-turbine temperature) is above 200°C the TSLM will decline the start since the risk of hotstarting is high.
Performing a dry-run operation would almost always cool the engine down sufficiently.
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When the aircraft bus voltage is below 20 Vdc the TSLM will decline a start since the risk of hotstarting is high.
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When the EHT valve (fuel-derichment on FCU) is not detected electrically by the TSLM, that start will be declined.
Starting the engine efficiently
The TSLM is capable of making more efficient use of available resources such as aircraft battery power as well as minimizing the
operational wear on components by discontinuing them when they are no longer required:
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The igniters (& spark-plugs) are discontinued when the main fuel ignites in the engine.
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The ignition / start fuel valves are similarly discontinued when the engine lights up.
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The starter-motor is discontinued when the engine speed (N1) reaches idle speed.
Beta propeller speed limiting
The TSLM senses when the propeller of the Walter M601 is operated in reverse / beta mode and will limit the propeller speed
as required in this mode.
Anti-flameout operation (new)
The TSLM is adaptable to include new features. Anti-flameout operation is a feature added recently to contribute to
safe engine operation. In this mode the igniters and ignition fuel valve is activated as a precautionary measure against
engine flameout. This mode is manually initiated by the pilot should weather or other conditions dictate such a
precautionary measure.
Monitoring, recording and indicating exceedences
The TSLM monitors ITT, N1, N2 & voltage continuously to fulfill its control functions. Additional to this it can accept sensor
inputs to measure torque and oil-pressure through minimal wiring. This information can be sent to displays for engine monitoring
via either RS-232 or CAN interfaces.
The TSLM will record to memory any exceedence of either ITT, N1, N2 or Torque. These exceedence graphs can be retrieved
from the unit similar to start and run graphs and viewed on a laptop computer. They will reveal whether an exceedence
requires major or minor followup inspection and/or repair.
The new generation TSLM will also indicate an exceedence via the EXCEED (indicator) output to alert the pilot to
take corrective action:
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The ITT sensing wires may be incorrectly swapped around on the engine thermo-couple terminals (eg. after maintenance on engine)
which can only be detected when the engine lights up during a start. The TSLM will not be able to prevent a hotstart in this
event, but will however light the EXCEED indicator to warn the pilot of the risk. It's up to the pilot
to pull the condition lever to shut-off and abort the start.
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Also during the start the EXCEED indicator will be lit up by the TSLM when the ITT exceeds 700°C which is only reached
when TSLM is unable to limit the start sufficiently.
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The EXCEED will also light up whenever either ITT, N1, N2 or Torque exceed their respective exceedence levels. Corrective action
in this case may involve just reducing the power (throttle) setting.
Diagnostic test and trouble shooting
In an effort to ensure the correct wiring of the various parts of the TSLM circuit especially before performing that very first
start, we have devised diagnostic tests that verify each section of the circuit in isolation.
Other features and more info
The TSLM is a one box solution to provide start, limit, monitor, alert and record functionality for the Walter M601 engine. It
greatly reduces the wiring involved. It saves both space and weight to other solutions.
More information regarding the operation and installation of the TSLM system can be found in the relevant manual listed
in the righthand column of this web page.
Also in the righthand column are screenshots of our System Link software running on a laptop connected to a live system.
One shot shows the real-time parameters displayed on gauges and in time-graph format, while the other shows a start-graph
recorded by a TSLM.
TSLM unit upgrade program
We currently offer an upgrade program for customers having 1st generation TSLM units. We will exchange any working
1st generation TSLM (serial numbers below 5000) for a new generation TSLM unit for the cost of only 1,100 USD.
Operational Record
TSLM's have been installed in many aircraft around the world equipped with either the Walter M601D or M601E engines.
Our gallery page has some pictures and videos for you to view.
