Today's Message Index:
----------------------
1. 03:21 AM - Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** (FLYaDIVE)
2. 03:30 AM - Re: Trouble starting a 912 ULS (FLYaDIVE)
3. 03:48 AM - Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** (SIDESLIP)
4. 04:02 AM - Re: Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** (FLYaDIVE)
5. 11:04 AM - Re: 914 Alternator Options (ploucandco)
6. 11:38 AM - Re: 914 Alternator Options (ploucandco)
7. 12:02 PM - Re: 914 Alternator Options (Jan de Jong)
8. 04:27 PM - Re: Trouble starting a 912 ULS (Roger Lee)
9. 04:28 PM - Re: 912UL Will not start on UL91 (Roger Lee)
10. 04:37 PM - Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** (Roger Lee)
Message 1
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| Subject: | Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** |
Chad:
Three things come to mind:
1 - You have a prop/engine balance issue and it shows up at a a particular
RPM range.
2 - You have a gear train issue - Someone else can comment on this.
3 - You have a control surface rigging/flutter issue. <-- This is low on
my guess factor list.
*Barry*
On Thu, Aug 1, 2013 at 9:35 PM, SIDESLIP <Chad2007@rogers.com> wrote:
>
> Hello all. I've got a Zodiac 601 XL-B with a Rotax 912ULS and a warp drive
> three blade.
>
> It's set at 15 degrees pitch, giving me 5500 RPM CLIMB OUT, 5200-5300
> static. This engine runs flawlessly on the ground. It has only 175 hours on
> the engine. New plugs, carbs synced, oil changed. Fresh fuel lines. All
> parameters are well within margins. Climbs and runs like a top, and is
> happy at 5500 cruise. The airplane does 100-110kts straight and level at
> 5500 rpm. Fuel burn is approximate at 3.5-4.1 gal/hr.
>
> I fly my pattern at 90kts, with 70-80 on final.
>
> When I pull the power back gradually to slow it for flaps and turning
> base, anything under 4k and it shakes and thuds. Maybe that speed unloads
> the prop? I don't know. Like I said, runs like a top on the ground. It's
> only running like a bag of hammers in the circuit pulling back under 4k. It
> is a slipper clutched plane.
>
> Any help is appreciated!
>
> Thanks in advance!
>
> Chad
>
> --------
> C-GYXQ. 912ULS. 601XL-B
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=405795#405795
>
>
Message 2
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| Subject: | Re: Trouble starting a 912 ULS |
John:
1 - What does the gear engagement points look like? If the gears are too
new to show ware take some blue Dykem and coat the ring gear teeth and the
starter gear teeth. Then try starting. You will have wear marks showing
the gear contact - If they are not straight and even from face to face you
have an alignment issue.
2 - If the gears are not engaging - Could the mounting system be totally
incorrect? Am I to assume at one point and for a long time there were NO
starting issues? If so... What changed?
3 - Any hard landings?
*Barry*
On Fri, Aug 2, 2013 at 12:00 PM, John Elling <jelling@newmexico.com> wrote:
> jelling@newmexico.com>
>
> Folks,
>
> I've gradually had trouble starting a ULS with the 912 Rotax high torque
> starter. First it did not like starting when it was cold. Then the sprag
> seemed to come disengaged without turning the engine over enough to start.
> Finally I started getting a gear-grinding noise. Then eventually the
> gears never engaged; just a grinding noise.
>
> I checked the starter alignment between the two ears for the bolts.
> Perhaps a 0.010" difference between the gaps of the two ears and no way to
> adjust that I could see since the ears of the starter flange are threaded
> as are the bolt holes on the engine.
>
> I removed the Rotax starter and found the gear surface was a little rough
> as was the mating gear teeth inside the engine. Probably from the
> grinding... I replaced the starter with a Skytec, aligned as best I could
> to exactly the same position as the Rotax starter (off about 0.010" between
> the top and bottom ears of the starter flange and the engine surface). The
> Skytec starter does exactly the same thing - grinds the gears without
> really engaging.
>
> Anyone have any ideas? Anything I should check before I start taking
> apart the engine to get to the starter gears and clutch?
>
> John
>
>
Message 3
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| Subject: | Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** |
Brand new prop. Brand new hub. Brand new extension. Smooth as silk at full throttle.
When I mean runs rough below 4000, I mean its only firing on half the cylinders.
It's THAT sputtery. Although yesterday I flew it and brought the power
back REALLY slowly, and it didn't seem to do it hardly all the way to idle.
I let it idle, as I lost altitude, then smoothly smashed it to the firewall. ZERO
hesitation and took me from 50kts DIRECTLY to 100kts! Stuffed me in the seat.
I was pleasantly shocked. The slipper was checked by a Rotax tech only 20
hours ago. It was good.
The throttle cable thing sounds legit to me....
--------
C-GYXQ. 912ULS. 601XL-B
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405847#405847
Message 4
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| Subject: | Re: Rotax 912ULS Stumble below 4000 RPM on final |
ONLY**
It is difficult to play doctor over the internet. You have to be a bit
more accurate in your description and what you have already checked.
"Smoothly Smashed" is an oxymoron. Either you smoothly advance the
throttle or you smashed the throttle. You say "I mean its only firing on
half the cylinders. It's THAT sputtery."
What jumps into mind is:
Condition of Spark Plugs
Condition of Spark Plug Wires
Mag output
Fuel Pump - Fuel Flow
Have you checked these issues? And YES, you can have a good spark and
running condition at High RPM and lousy at low.
*Barry*
On Sat, Aug 3, 2013 at 6:48 AM, SIDESLIP <Chad2007@rogers.com> wrote:
>
> Brand new prop. Brand new hub. Brand new extension. Smooth as silk at full
> throttle. When I mean runs rough below 4000, I mean its only firing on half
> the cylinders. It's THAT sputtery. Although yesterday I flew it and brought
> the power back REALLY slowly, and it didn't seem to do it hardly all the
> way to idle. I let it idle, as I lost altitude, then smoothly smashed it to
> the firewall. ZERO hesitation and took me from 50kts DIRECTLY to 100kts!
> Stuffed me in the seat. I was pleasantly shocked. The slipper was checked
> by a Rotax tech only 20 hours ago. It was good.
>
> The throttle cable thing sounds legit to me....
>
> --------
> C-GYXQ. 912ULS. 601XL-B
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=405847#405847
>
>
Message 5
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| Subject: | Re: 914 Alternator Options |
Jerry, to answer your specific question about opening the ROTAX gearbox to install
an alternator on the vacuum pad, I consider it to be the work of a ROTAX specilised
mechanic. Nothing really complex, but this is not really easy to open
the gearbox if you don't have the right tools and don't know how to do (have
followed the ROTAX maintenance course).
Concerning adding an extra alternator, I have myself a 914 powered Europa. I added
an alternator on the crankshaft based on Jim Butcher informations (see the
link from Gilles). That works very well.
In fact, you have the following options:
- extra alternator of ROTAX is NOK as doesn't fit under the Europa cowling.
- 20A B&C on the is a good option but adds weight and you need to open the gearbox.
The added weight is fully in the front, that just add on top of your airmaster
(I would expect that you use a good constant speed prop with a 914). Also
20A extra could be limited if you have a 2 axis AP, lights, a decent panel and
a pitot heater...
- 40/60A B&C on the crankshaft is the way to go if you are consuming much power
and are not willing to be dependable on the ROTAX/DUCATI. regulator. It is a
bit heavy but works very well. Well, if you have your engine already installed,
this is not really easy to install the whole setup
- the flygas solution that Jan mentioned was also on my short list but I removed
it based on cost (around 1000EUR) and the low output power 10-14A.
- ROTAX 912is second alternator on the crankshaft. This is a solution similar to the one of flygas but coming directly from ROTAX. The output is about 30A from 2000RPM. Don't know about price (likely not cheap, but ROTAX quality), but that would be my prefered solution if I had to do it again today. You can find more infos in the 912is illustrated part catalog: http://www.flyrotax.com/portaldata/5/dokus/d05447.pdf and the 912is installation manual http://www.flyrotax.com/portaldata/5/dokus/d05455.pdf
Hope this helps, Jacques.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405867#405867
Message 6
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| Subject: | Re: 914 Alternator Options |
Well, I just reviewed the 912is part catalog and I found out that you need to replace
the whole original generator setup of the 914 with a new one from the 912is
to get 2 generators and 2 regulators. As this is also where you have the
pick-up coils, I would think that it is way more difficult than what I first thought.
So it was an interesting but not really feasible as it seems.
Jacques.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405870#405870
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| Subject: | Re: 914 Alternator Options |
Hi Jacques.
The 912iS alternator is oil cooled and needs the 912iS engine block, so
that option seems definitely out.
Jan de Jong
Message 8
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| Subject: | Re: Trouble starting a 912 ULS |
It sounds like you may have lost your sprag clutch that engages the engine with
the starter then releases as soon as the engine speeds past the starter rpm.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405877#405877
Message 9
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| Subject: | Re: 912UL Will not start on UL91 |
91 oct or 100LL should have had no affect on starting alone. Something else had
to be involved and masking the issue.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405878#405878
Message 10
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| Subject: | Re: Rotax 912ULS Stumble below 4000 RPM on final ONLY** |
Carb sync, I hope mag drop is fairly equal and gearbox checked to see if it needed
re-shimming? Even with only 175 hrs. if a plane has been around years things
like the Bellville washers in the gearbox get crushed and need to be re-shimmed
or replaced.
I could easily be throttle cables not moving perfectly in sync as you throttle
up and down, especially down. Going up should be smooth.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405879#405879
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