View Full Version : Wren auto start
04-13-2009, 08:29 AM
After flying my wren pred last week and giving her the rag spanner back at my workshop,i put her to bed.
sunday was a good day for it so out she comes, usual pre flight checks,at the field.
tried to spool her up ,and all i got was a buzzing sound i shut her down checked every thing through nothing visable to be at fault ,tried again same buzzing ! but this time i disconected the starter from the ECU buzzing stopped ! So the fault lies with the starter, pulled the startter out tried again but this time the starter spooled up but the bendix did not activate , i flushed the shaft with an aerosol cleaner and worked a little sillicone oil into the bendix viola ! it worked refitted the starter did a restart and shut down to ensure it would spool down and cool off correctly yup its ok now !
1, Has any one else incured this problem
2, is there a spacific lube which should be used
3, in general maintenance of the machine/turbine should this be stripped/cleaned after X Number starts or hours
04-13-2009, 08:37 AM
I suspect the scenario where the ceramic bearings have grouped at the bottom and the standard starter voltage settings are not enough to break them free first start.
I have the change in settings to up the voltage if you need.
It gets better over time but a lot of them do it.
04-13-2009, 09:03 AM
I've had the same problem. Another thing to check is to make sure that you have some oil on the bendix starter cone. I use the Triflo on it and it works fine.
Ron is correct on the turbine shaft hanging up. I use a 1.5MM driver and carefully and gently insert it through the mesh of the FOD and turn the compressor very gently. It only needs to turn about 20 degrees and its free.
I guess you can also turn up the start voltage on the starter as an option.
04-13-2009, 02:31 PM
cheers guys !
it did occour to me that the turbine could be jammed ,i did how ever gently turn over the turbine by hand using the output from the second stage to check, it span up without any resistance.
i have to admit that it never occured to me that it could be the main bearings after only 7 hrs flawless run time !!!!!!
so a good point well put which i shall BEARING in MIND (could not resist that)
once again cheers freaks keep the info flowing ! ! !
04-13-2009, 03:05 PM
I'm sorry, but I had to laugh a little bit....OK A LOT!! :):) I'm not laughing at you, only at the thought of you spinning the output..."Yep Turbine's GOOD!!" :)
By turning the output of the second stage, you did NOT turn over the turbine...There is no direct connection between the two.
So of course it spun easily by hand...:)
04-13-2009, 03:17 PM
I was under the impression that these starter motors were pretty high torque devices anyway and would cope with any friction.Does the shaft really get that tight when the bearings pool?
04-13-2009, 03:30 PM
The motors will do the trick for sure but for some reason, some of the ceramics let the balls drop together at the bottom of the race and then it takes a little oxtra kick to free them up.
I bumped up my start voltage (current) and it only happens once in a great while now.
Here you go -
Sticking bearings are a pain - and no-one, not even the manufacturer, knows why they do it. Try upping the power to your starter motor as follows:
You need to change the parameters as follows: on turning on receiver/ECU
press the minus sign button then the V button quickly. This will get you
into the parameters menu.
Change the following
parameter 17 change existing number to 100
18 to 3
19 to 1
22 to 35
Check that the following parameters are correct
parameter 28 is 2
29 is 7
30 is 2
04-13-2009, 03:37 PM
Kicking a man when his balls are stuck together; that's just not right. :banana
04-13-2009, 03:45 PM
I WAS NOT kicking.....I just had a good chuckle is all....Well a belly laugh.....
It's a common misconception....It just struck me funny is all...
04-13-2009, 05:29 PM
yep u are right m8
I SHOULD HAVE KNOWN BETTER !!!!!!!!!
but when u are on the strip ready to go an it doesnt
much scratchin of pea for brain go to plan B
twirl the bits that will twirl !
when all else fails
go to pits an do a proper diagnosis .
04-13-2009, 05:30 PM
cheers m8 for the support