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Manual restart:
User can normally shutdown the ECU through the transmitter (by lower-
ing the stick and trim). The ECU will execute the normal shutdown and post run cooling cycle.
Once the cooling is finished (temperature below 100ºC), the ECU will return to power-up state
allowing the engine to be restarted through the normal procedure (Trim-up, cycle stick). The time
to shut down and later start is exactly the same as standard operation. This mode is useful for
gliders, where the engine is used to climb to height, shutdown, soaring, restart, climb, etc. This
mode does not pose any safety hazard besides the fact that the engine can be started inadvertent-
ly if the start procedure is executed in the transmitter after the flight.
Autorestart:
In particular case of a fuel bubble that momentarily stops the combustion,
the ECU will detect this condition by monitoring the rpm, temperature and pump power, and then
the ECU triggers the auto-restart sequence. This sequence is done with the engine hot, so the
power is restored quickly. This restarting function can help save the plane in few limited circum-
stances.
But it can also greatly increase the risk of fire, so before to enable this function, please
read and understand the following:
What does the auto-restart function does:
It automatically tries to restart the engine quickly and restore the power setting that is being
asked by the transmitter. To trigger this function, the ECU checks:
The radio signal is valid, no failsafe condition.
The readings of the RPM are consistent with a flameout condition (the speed of the RPM
coasting down is between preset limits).
The readings of the exhaust temperature are consistent with a flameout condition.
The battery voltage is good.
No other faults detected.
Once the ECU is satisfied that the shutdown/flameout was most likely caused by an interruption of
combustion, usually caused by an air bubble, the ECU triggers the quick restart function, where
the ignitor is energized to full voltage and the pump is started at a power dependent of the current
engine status (RPM and EGT). Once the ECU detects that the combustion has reassumed, the
starter power is set to full power to reach the idle rpm as quickly as possible, and the pump power
is increased accordingly to the real RPM increase, allowing for delays caused by bubbles arriving to
the engine. If after 10 seconds of restart the ECU doesn’t detect a stable combustion, the proce-
dure is aborted and the normal cooldown initiated.
What the Autorestart function will not do:
It will not restart the engine if the shutdown was caused by any fault other than a typical
flame out caused by air in the fuel system.
It will not monitor and confirm flight conditions are optimum for a restart. Leaving the re-
start to progress is the pilot responsibility and decision, depending on each particular case.
When should Autorestart function be enabled?
Auto-restart is fast but still takes an average time of 10s to establish restored level of pre-
shutdown power. It is highly recommended that Auto-restart only be used on airframes capable of
