Today's Message Index:
----------------------
1. 01:03 AM - Re: Rotax 912 Carburator Sockets Problem (Richard Girard)
2. 04:33 AM - Re: IDLE RPM (Thom Riddle)
3. 04:46 AM - Re: IDLE RPM (Thom Riddle)
4. 05:37 AM - Re: IDLE RPM (Roger Lee)
5. 07:25 AM - Re: IDLE RPM (lucien)
6. 07:54 AM - Re: Rotax 912 Carburator Sockets Problem (ricklach)
7. 08:07 AM - Re: IDLE RPM (Thom Riddle)
8. 10:12 AM - Re: IDLE RPM (Roger Lee)
9. 10:32 AM - Re: Rotax 912 Carburator Sockets Problem (Roger Lee)
10. 10:38 AM - Mag wiring (was IDLE RPM) (Craig Payne)
11. 11:11 AM - Re: Rotax 912 Carburator Sockets Problem (Turbo_Boss)
12. 02:24 PM - Re: Mag wiring (was IDLE RPM) (david park)
13. 02:34 PM - Re: Re: IDLE RPM (Duncan & Ami McFadyean)
14. 06:59 PM - Re: IDLE RPM (Roger Lee)
Message 1
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| Subject: | Re: Rotax 912 Carburator Sockets Problem |
The white powder is probably the result of corrosion of the aluminum, i.e.
aluminum oxide. I've not seen this type of separation of carb sockets
before, the usual failure is cracks in the interior of the socket that
causes air leaks and can destroy the engine.
There was a bad batch of sockets produced a few years ago that were fitted
to both the 912 and the HKS engines. I replaced mine with the JBM units and
have seen no cracking since, although inspection and replacement of the carb
sockets is a regular maintenance item checked off at 100 hour and annual
conditional inspections.
Rick Girard
On Mon, Jul 26, 2010 at 11:32 PM, Turbo_Boss <turbo_boss@cwpanama.net>wrote:
> turbo_boss@cwpanama.net>
>
> Hello guys,
>
> I have problem with the Rotax 912 carburator sockets were the rubber get
> separated from the steel insert part.
>
> In my club, almost everybody with 912 engines, has exactly the same problem
> with these carburator sockets showing the same type problem.
>
> Please look at the pics. My 912 is like 18 months old and it only have 52
> hours of use and this part have fail. Also, you will see a white powder. I
> dont know what is that.
>
> Also, I was checking the net and found this company that produce 912 socket
> carburators in USA and they say they are better than the Rotax ones.
>
> http://jbmindustries.com/
>
> Have any one have try these JBM 912 carburator sockets? Are they better?
>
> THX,
>
> Isaac
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=306411#306411
>
>
> Attachments:
>
> http://forums.matronics.com//files/rotax912carburatorsocket_a_759.jpg
> http://forums.matronics.com//files/rotax912carburator_socket_2_177.jpg
> http://forums.matronics.com//files/rotax912carburator_socket_1_376.jpg
>
>
Message 2
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Roger,
I am assuming your CT is the SW since that is the more common of the models sold
to date in the USA. If my assumption is correct your airplane does not have
the very high aspect ratio wing that the Allegro has plus its wing area is considerably
smaller than the Allegro's and the typical flying weight is a good bit
heavier with the same payload. The net result is your airplane has a much heavier
wing loading and span loading, both of which dramatically affect the descent
rate at idle power or power off.
CTSW/ Allegro 2000
Wing Span 27'-11"/ 35'-6"
Wing Area 107 sqft/ 122.5 sqft
Aspect ratio 7.29 / 10.29
Typ.Wt w/ sam load 1200 lb/ 1100 lb
Wing loading 11.2 lb/sqft / 9.0 lb/sqft
Span loading 43.0 lb/ft / 31.0 lb/ft
Of these factors, the one that most affects descent rate is the span loading. That
is why gliders and sailplanes have such high aspect ratio wings.
Due to these major differences in the wing design, an idle speed as high as you
recommend in an Allegro 2000 will dramatically reduce the idle power descent
rate and extend the idle power glide compared to a CTSW with the same idle speed
regardless of piloting technique or approach speed.
My Kolb Slingshot has 22' wing span and 110 sqft of wing area with a 4.4 to 1 aspect
ratio. During a typical flight it has a wing loading of 7.5 lb/sqft and
a span loading of 37.3 lb/ft. My approach speed in the Slingshot is 55 mph with
full flaps as it was in the Allegro 2000. At idle power I get a descent rate
of 1500 fpm in the Slingshot and the Allegro was 700 fpm at same airspeed with
full flaps. Both of these were without slipping.
Bottom line is that what airframe the engine is installed in makes a huge difference
in acceptable idle speed for short approach capability.
--------
Thom Riddle
Buffalo, NY (9G0)
Kolb Slingshot SS-021
Jabiru 2200A #1574
Tennessee Prop 64x32
The truth will set you free. But first, it will piss you off.
- Gloria Steinem
Read this topic online here:
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Roger,
A bit more on descent rate differences. I just did my BFR in a Pitts S2-B. Its
idle power descent rate at normal approach speed is 2500 fpm and this airplane
has no flaps.
This bi-plane has 20' wings and a total wing area of 125 sqft. MTOW is 1625 lb.
and flies like a high powered rock with exceptional flight controls.
--------
Thom Riddle
Buffalo, NY (9G0)
Kolb Slingshot SS-021
Jabiru 2200A #1574
Tennessee Prop 64x32
The truth will set you free. But first, it will piss you off.
- Gloria Steinem
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306424#306424
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Howdy Thom,
Nice to hear from you again. Hope you are staying out of the heat and humidity.
It's been a little too humid here with the heat lately. It's our monsoon time.
We kind of got off the original topic question about gearbox and idle rpm. While
we are on it. You can momentarily shut down one mag and then after the rpm drops
some shut down the last one. It will help with that final hard stop to the
gearbox.
The Allegro does have a longer wing than my CTSW, but I have flown both and they
land very similar. To me the key in our light planes is being able to round
out at 12" or less off the deck and hold the stick steady without pumping it until
touch. Just a tad more back stick as it descends.
I agree if we are trying for a short field landing, no power is better. Even in
a good gliding aircraft the speed and decent rate can be controlled with the
stick. Pull that stick back far enough and the plane will slow and descend, not
to mention if we find ourselves too high we can slip. When we are at an idle
powered approach we can keep the approach speed around 50-60 which ever you use
for your plane. If I carry power like 2800 rpm to the touch I can keep it at
the same speed by pulling the stick back. Will I have a slightly longer roundout
at the bottom, yes, but I don't care about the extra 75'-100' because all
I'm looking to do is have better rudder and elevator authority with the prop
wash and slightly reduce the sink rate at roundout to make a nice soft touch.
I too had a Kolb Mark III and I used the same rpm to touch which made it much
more controllable at really slow speeds and always a nice soft touch.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306426#306426
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Roger Lee wrote:
>
> You can momentarily shut down one mag and then after the rpm drops some shut
down the last one. It will help with that final hard stop to the gearbox.
>
>
Don't mean to jump in, but I've always been skeptical of this particular shutdown
procedure. In fact, I had a nasty fight with a guy about it on another list
not too long ago to the point he ended up sending me almost mentally-ill private
emails about it and I had to cut the exchange off.
But you and Thom are "da men" on the Rotax so I don't feel bad about commenting
on this and I'd be interested in your input.
My observation on my 912ULS has been that the really hard stop that joggles the
gearbox is far below even 1400 rpm - it's nice and smooth when cut off until
it gets to that very low rpm. And, to my mind, the staggered mag shutdown method
actually introduces the possible hazard of idling the engine, if only momentarily,
below 1400 rpm while it's running on only one mag at that point. I should
think that that would be worse long-term than the part you _can't_ do anything
about no matter what, which is the joggle right as the engine comes to a
stop.
So it seems to me you're just as well off killing the engine straightaway from
1800 or 2000 rpm, thus avoiding the possibility of too low of an idle with the
engine still running. Like I said, you can't really do anything about the joggle
at the very end, since that occurs at an rpm that's far below where the engine
could even run anyway.
Anyway, like I said, I'm just skeptical of the value of doing the staggered mag
shutdown. I can't really see what it buys you and it has the drawback of the
possibility of a too-low idle during shutdown.
But of course, I'm fully prepared to be wrong and learn if there really is a benifit
to doing this?
Thanks,
LS
--------
LS
Titan II SS
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| Subject: | Re: Rotax 912 Carburator Sockets Problem |
I have used the JBM Industries sockets with great success and cost savings on more
than one 912/914 engine. I think they are as good as, or better than, the
ones sold through Rotax at twice the price. BUT, looking at your pictures the
real problem is moisture. Everything has a layer of corrosion on it. Your environment
seams to have a lot of moisture and that is the problem. It looks like
you will be replacing the carb sockets and probably other items as a regular
scheduled maintenance requirement.
Rick
--------
701Driver
N35 26.700, W118 16.743
Read this topic online here:
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On all the 80 hp 912 UL engines and the one 80 hp 912F3 I help to maintain, I've
done a mag check at my preferred idle rpm of 1600 and got virtually no rpm drop.
I've only done this on engines with well balanced carbs and would not even
consider doing it on an engine with the carbs out of balance.
I don't see any advantage of doing a sequential mag grounding rather than simultaneous
grounding of both mags, at least in the lower compression engines. Can't
speak with any authority on the high compression 912 engines but don't see
any advantage in theory.
However, as Lucien pointed out, if it is important to have the idle speed of the
hi-comp engines at 1800 minimum idle rpm (hot) and shutting off one of the mags
results in an rpm drop, this seems to be contradictory advice. If it does
something strange like kickback upon shutdown at high idle speed, maybe the high
idle speed is not such a great idea or something else is amiss.
I've never seen any problem at normal shutdown of the 912ULS engines I've worked
on with the hot idle speed set at 1800 rpm (and well balanced carbs). Most aircraft
mag switches, at least those made in the USA and installed on GA aircraft,
including the Diamond Katana with 912F3 engine, do not have the capability
to ground the two mags independently, so the question is moot on those aircraft.
--------
Thom Riddle
Buffalo, NY (9G0)
Kolb Slingshot SS-021
Jabiru 2200A #1574
Tennessee Prop 64x32
The truth will set you free. But first, it will piss you off.
- Gloria Steinem
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306442#306442
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Hi Lucien and Thom,
One of the first things to consider here with the gearbox is what prop people use.
Is it a light composite or a heavy 72" nickel edge Warp Drive. I have a 66"
Warp, square tip on my plane. Rotax doesn't want anything over 68" when using
the heavier props like a like Warp and no nickel edges.
That said I just turn both of my mags off all at once and don't worry about it.
The technique I stated is right out of a Rotax class with Eric and this very
question was answered. You don't let one mag set for a long while it is just for
a few moments to help reduce some rpm. The rpm issue and vibration is usually
directed at people who tend to let them idle like that for long term. The gearbox
pounding should not be an issue for a few moments, but will be for those
who allow this to be the norm at idle during warm up and taxi. And like we have
talked about here, it is not as big an issue with the lower compression 80
hp as the 100 hp Rotax.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306465#306465
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| Subject: | Re: Rotax 912 Carburator Sockets Problem |
I agree with both these gentlemen.
This is corrosion and most likely from water or a very high humidity area. Once
it starts this process the rubber will come away from the metal. If you live
in a high moisture environment I would spray down a large part of my engine and
exposed parts (metal and rubber) with Boeing T-9 (my first choice as it is a
more dry application) and Corrossion -X is my second choice (a little wetter
after it is applied). These will block out the rain or moisture.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306469#306469
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| Subject: | Mag wiring (was IDLE RPM) |
While speaking of mag wiring and for those of you wiring your own plane: as
I understand it if you want to install Bully Hawk's soft-start module you
can't use a conventional left-right-both-crank switch. You need to be able
to crank on one mag (the one the soft-start module is installed on).
-- Craig
Message 11
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| Subject: | Re: Rotax 912 Carburator Sockets Problem |
Thank you all for your replys. Well I live in Panama Republic of Panama, Central
America. Here the humidity is almost 100% [Crying or Very sad] This is like
living on the middle of a rainforest.
I will follow your advises and use Corrosion-X or similar product to spray around
that parts after I use my UL.
I will advise my other friends to do the same.
I Hope this cure this problemo.
Thx,
Isaac
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306472#306472
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| Subject: | Mag wiring (was IDLE RPM) |
I have the soft start module on mine - not flying yet - with the left right
both start switch. Intend to select right then start with seperate switch
then both??. Can anyone see a problem with that?
Dave
> From: craig@craigandjean.com
> To: rotaxengines-list@matronics.com
> Subject: RotaxEngines-List: Mag wiring (was IDLE RPM)
> Date: Tue=2C 27 Jul 2010 10:36:34 -0700
>
n.com>
>
> While speaking of mag wiring and for those of you wiring your own plane:
as
> I understand it if you want to install Bully Hawk's soft-start module you
> can't use a conventional left-right-both-crank switch. You need to be abl
e
> to crank on one mag (the one the soft-start module is installed on).
>
> -- Craig
>
>
===========
===========
===========
===========
>
>
>
Message 13
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That is not correct!
Try landing in a marginal 350 yard strip with hedges at both ends and trees
close to approach (meaning rotor and the need to keep speed up meaning a
lower rate of descent at approach speeds). This is the strip I use
routinely.
With a 2 knt tailwind you'll miss it. With a 2knt headwind - easy.
Crosswinds are the worst as no headwind component, additional turbulence and
need for greater margin above stall.
Being able to pull back the idle makes a significant difference to sink
rate and the ease of getting in (=safety); of course, in flight that doesn't
mean 1200rpm, more like 2000, but it would be 1200 if the 'plane were not
moving through the air.
Of course you'll maybe say 'find a better strip', but life is full of
compromises!
Duncan McF.
----- Original Message -----
From: "Roger Lee" <ssadiver1@yahoo.com>
Sent: Monday, July 26, 2010 2:09 PM
Subject: RotaxEngines-List: Re: IDLE RPM
>
>
> Hi Guys,
>
> Thom, my CT has a glide ratio of 14:1. many people at first had high
> approaches and landing speeds too fast. We all found out that flying a
> high glide ratio quick handling plane is different from most GA aircraft.
> It is all in the set up , lower, better approaches, slower speeds, early
> setup, better spot landings. I use 3800-4200 in the late downwind and
> base. Then I reduce throttle to 2900-3000 rpm on final. I let that stay
> all the way to the ground. I have found that it is all about setup and
> speed control and proper positioning in the pattern. Many of the CT people
> can set it down in 1000' or hit a spot on the runway. Flying a CT or an
> Allegro or any fast handling, high glide ratio plane makes people a better
> pilot and helps hone their skills. No plane is really bad it is all in
> what you get used to and how much you practice to make you better. No
> matter if he is at 1600 or 3000 rpm at landing the stick will control his
> speed and ultimately his sink rate. I personally don!
> 't think rpm is as big a factor as people think, they just need to change
> the way they setup their landings in their minds.
>
> --------
> Roger Lee
> Tucson, Az.
> Light Sport Repairman - Maintenance Rated
> Rotax Repair Center
> 520-574-1080
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=306303#306303
>
>
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Hi Duncan,
I was challenged to do this on a 300m strip which is about 1000' by some friends
in the UK that said they needed to have that low an rpm to land. So I took it
to task and measured off the runway up at an airport. No trees, but it was easy
to do at idle or 2800 rpm with 30-40 flaps with an approach speed of 50 knots.
You just had to hit the beginning of the runway and leave nothing behind.
I do it on a dirt strip up from me and it is 1700' and I use 30-40 flaps on it
over the trees and make it down. If you miss your spot or land too fast then
good brakes can be a must.
The other person didn't say he had lots of obstacles. If the runway is open it's
very doable. Add high obstacles and we have an all together different scenario.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=306513#306513
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