Rotax 912uls/s Hard Starts.

boldv · Post by **boldv** » Thu Mar 05, 2009 12:52 pm

Are we alone?
I am a co-owner of a motor glider with a Rotax 912s3 with 480 hrs. fitted. We recently had the sprag clutch replaced and at the same time the slipper clutch was shimmed out to give the top end torque setting. The work was required to cure non/or "hard " starting. This was not cheap and we do not want it to happen again but....the odd hard start is starting to occur again.
Yes we have the h/duty starter motor. Yes we have a high cap battery (35ah) with p/v charging. The factory installed leads to the charger are about 2 feet max in length. All seems in good order.
There are no problems starting when the engine is warm.
When I mentioned the problem to a group of pilots at an LAA meeting a few days ago it seemed that I was the only one who had heard of the 912s or uls "Hard Starts".
Yes I would like to fit the "Soft Start Module" but the aircraft is Group A. and the module is not likely to be approved.
Any useful comments please?
Boldv.

Rod1 · Post by **Rod1** » Thu Mar 05, 2009 2:40 pm

This was a problem on some MCR01 aircraft but the HD Starter appears to have solved it. I would contact Conrad at http://www.conairsports.co.uk.

Rod1

Andy Draper · Post by **Andy Draper** » Mon Mar 09, 2009 11:40 am

Take a look at the Standard Modifications section of the LAA web site, under the 'Rotax Engines' heading. You'll see that the Soft Start Module has been LAA approved.

mike hurn · Post by **mike hurn** » Mon Mar 09, 2009 12:10 pm

I have been told that these soft start modules are going to be Rotax approved parts and possibly fitted as standard on new engines

Rgs Mike

NJ673 · Post by **NJ673** » Mon Mar 09, 2009 1:13 pm

No you are not alone!

If your CofA does not permit the use of the soft start module then there is still a few things you could do. Firstly fit the HD starter, and change your battery, if yours is still the original one[preferably for a new Odyssey battery, if your CofA conditions allow].

If you have power in your hangar then get hold of a specialist battery trickle charger/conditioner they cost about £40 or so from Motorcycle shops so that your charge is always maximum on initial start. When starting the engine do whatever priming routine you do then if your start system will permit, turn the engine over for a few revolutions with the mags switched off. Once the engine is up to starter speed flick one mag on then the other after the engine has fired up. In really cold weather I point the space heater at the engine for 10 or 15 minutes during preflight it responds really well to a bit of preheating.

This sort of procedure wont totaly eliminate kickback/hard start but will help reduce it until such times as a soft start module can be fitted. Many 912S/ULS engines begin to experience these sort of start difficulties upwards of 250/300 hrs.

Lastly dont persevere with a start that is failing due to discharged or bad battery, throw the towel in early and charge it up.

Nick Allen · Post by **Nick Allen** » Mon Mar 09, 2009 1:36 pm

preferably for a new Odyssey battery, if your CofA conditions allow.
If you have power in your hangar then get hold of a specialist battery trickle charger/conditioner they cost about £40 or so from Motorcycle shops.

When I bought an Odyssey battery for my motorbike, the supplier specifically warned me against using a trickle charger/conditioner. He was adamant that the Odysseys didn't like these and preferred "normal" charging devices. (I had previously used an Optimate trickle charger/conditioner on conventional lead-acid batteries, on which it worked incredibly well. Highly recommended.)

Cold starting problems...your chokes are all working properly aren't they? (Sure that's obvious, but sometimes the obvious does get overlooked!)

mike hurn · Post by **mike hurn** » Mon Mar 09, 2009 1:53 pm

You proberly know already but i know some people that dont

for the choke to work on a 912/912s engine the throttle lever HAS to be completely shut on idle..... starting my 912s in this way it starts within 3 turns no problem at all

Rgs Mike

Steve Brown · Post by **Steve Brown** » Mon Mar 09, 2009 6:35 pm

Ref Odessy trickle charge or not .......

http://www.odysseyfactory.com/chargers.html

and quote from their Charging Manual

'The charger then enters into the trickle charge phase at 13.5-13.8V. The battery can be left connected to the charger indefinitely.'

Light Aircraft Association

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