Wren 44 TurboProp Users Manual. Copyright Wren Turbines Ltd February 2008 Page 31
First running
Confirm that your engine mounting is secure and that your plane is properly restrained by a helper. Keep
your ear defenders within easy reach – at high rpm the prop makes quite a lot of noise. Connect the starter
propane connector to the propane line or fill the propane tank to about ½ full if you have on-board propane.
Mix some clean filtered fuel with 5% oil and fill the tank.
Turn on the transmitter and receiver.
Confirm the battery is freshly charged and connected up. Go into the 2
nd
screen of the display where you will
see the battery voltage indicated – confirm you have 7.4v or more.
Go back to the opening screen on the display.
Confirm there is a temperature reading on the display.
Confirm your CO2 fire extinguisher is close at hand.
Ensure the running area is clear of onlookers.
Starting the engine
Ensure throttle stick and trim is set to down. Turn on transmitter then receiver if not
already on. ECU screen should come on.
Set trim to up – confirm display shows “Ready”.
Quickly raise throttle stick to full and back to off again, to initiate start. Do not touch
the stick again until the engine is at idle or the start will be terminated.
You will hear the engine giving a short spin and “ignition” will show on display. The
engine will slow down and the gas should be heard to light with a small “plop”.
The display should show the temp’ rising. If it is slow to do this abort the start and
adjust the blue propane adjustable flow control.
Once over 100’C the display will read “FuelRamp” the pump will start to supply fuel.
Fuel should then be travelling along the feed pipe towards the engine and as soon as
the fuel reaches the engine you will hear the engine note change. The engine and
propeller will start to accelerate and the engine rpm will rise past 30,000rpm as
shown on the display you may hear the starter disengage and continue accelerating
up to idle, at around 55’000rpm. If the engine slows below 30,000rpm at this time the
starter will automatically come back on to bring the speed back towards 32,000rpm.
Once the engine is running, leave it idling for 30seconds or so to alow a flow of
lubrication to be established to the gearbox before throttling up. When ready to shut
off, leave the engine for 30 seconds at idle for temperatures to stabilise before
returning the trim to off to shut down the engne. The ecu will then command a cooling cycle for the engine and you
can hear this as a series of spin-ups of the starter as the temperature reduces. Once the engine has cooled it will stop
cooling and you can shut down. Do not touch the throttle stick during cooling.
Things People Do or Don’t
If you find the engine blows out the propane gas during the start, it means the fuel had not reached the engine. In
this case, simply lower the radio trim to zero (which will terminate the start), wait for the engine to come to a halt
(about 20seconds), raise the trim and go for another start. If the propane blows out again repeat again but use a little
more propane by opening the blue adjustable flow control a little.
Batteries
– a common problem with starting is a fading ECU battery. The engine does many starts on one charge
and it is easy to forget to keep them topped up and a low battery can catch you out. Go into the 2
nd
screen in the ecu
and do a start and watch the battery voltage. If it dips below about 7.2v it needs recharging.
