Nervous about Rotax

On 2008-01-21, Jim Stewart wrote:
On the plus side, plugs cost $3/each and it only takes an hour to do plugs
and oil.

Yeah, but will I have to take it to my nearest Rotax service center to get
that done?

2000 RPM idle is fine. 2500 is good for warmup.

The comment I got a few times was that idling below 2500 will eventually
result in a broken crank.

Pluses for the Rotax are no thermal shock issues,

Why not?

will allegedly run for 30 minutes at 50% power with either oil or coolant
gone, and 5 gallon/hr cruise.

As opposed to 5.5 in the O-200. That's a negligible difference.

No mixture control.

What leans the mixture at altitude?

As for support, I've had no problems with my 912 so I don't have any
direct experience. I know that the west coast FlightDesign distributer
has worked closely with Rotax on some safety directive issues and has
gotten parts and support quickly.

If I break a crank, or blow a jug, how long will it take to get parts? I was
told that people are waitiing 6 months for jugs because Rotax is putting all
it can make on new engines.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
http://www.hercules-390.org (Yes, that's me!)
Buy Hercules stuff at http://www.cafepress.com/hercules-390

On 2008-01-22, Jay Maynard wrote:
No mixture control.
What leans the mixture at altitude?

Also, no carb heat (on many aircraft). How do you deal with carb ice?
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
http://www.hercules-390.org (Yes, that's me!)
Buy Hercules stuff at http://www.cafepress.com/hercules-390

Jay,

For not liking them, you know very little about them.

Pluses for the Rotax are no thermal shock issues,

Why not?

Water cooling buffers sudden temperature changes.


No mixture control.

What leans the mixture at altitude?

The automatic built into the carb (which is attached to the engine in a way
that keeps it from icing up, hence no carb heat.

--
Thomas Borchert (EDDH)

On 2008-01-22, Thomas Borchert wrote:
For not liking them, you know very little about them.

I'm always willing to learn more. What I've heard so far doesn't endear them
to me, but if what I've heard is wrong, then I'll change my mind. It would
certainly make my aircraft search simpler; as has been noted, there are lots
more LSAs out there with Rotaxes than with O-200s.

I believe it's much preferable to appear ignorant and learn than it is to
not ask questions and get it wrong.

Pluses for the Rotax are no thermal shock issues,
Why not?
Water cooling buffers sudden temperature changes.

Effectively enough? I would guess so, but it'd be nice to be sure.

No mixture control.
What leans the mixture at altitude?
The automatic built into the carb (which is attached to the engine in a way
that keeps it from icing up, hence no carb heat.

Okkay...so if no need for carb heat, why do some manufacturers include it?
For that matter, there's an article in the January Sport Pilot that talks
about, among other things, dealing with carb heat in the 912 by cycling the
throttle a few times.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
http://www.hercules-390.org (Yes, that's me!)
Buy Hercules stuff at http://www.cafepress.com/hercules-390

Jay,

Effectively enough? I would guess so, but it'd be nice to be sure.

Well, to answer that question you'd need to start with conclusive evidence that
there is such a thing as shock cooling in air-cooled engines. You won't find it
and many people having learned and forgotten more stuff about engines than I
will ever know doubt very much it exists. That siad, yes, it is commonly
accepted that shock cooling is not an issue in liquid-cooled engines.

Okkay...so if no need for carb heat, why do some manufacturers include it?

Because some manufacturers chose to install the carb in a different way or in
different circumstances which are more prone to carb ice.

--
Thomas Borchert (EDDH)

Jay,

I hit send to soon. Here are my thoughts from a German perspective:

- The Rotax 912/914 has been in service in Europe for decades now,
inpowered gliders and what's called ultralights here (the LSAs you see
in the US now). People are quite happy with it, the service history
seems completely normal.

- Germany is much smaller, so finding a service center can be much
easier than in the US. However, with the engine becoming more common,
mechanics in the US will have to adapt. They did here.

- The main problem I see is that the 912 doesn't really run well on
diet of Avgas exclusively. OTOH, auto gas contains increasing amounts
of ethanol - and while you can handle part of that with engine design,
choice of gasket and hose materials and so on, you cannot design away
the fact that ethanol will dissolve water which might freeze out at
high altitudes. That's something I would like Rotax to comment on
extensively.

--
Thomas Borchert (EDDH)

Thomas Borchert wrote:
Jay,

I hit send to soon. Here are my thoughts from a German perspective:

- The Rotax 912/914 has been in service in Europe for decades now,
inpowered gliders and what's called ultralights here (the LSAs you see
in the US now). People are quite happy with it, the service history
seems completely normal.


Not to mention that it is in the Predator UAVs but they probable switch
out engines like we would change the oil.

Jay Maynard wrote:
On 2008-01-22, Jay Maynard wrote:
No mixture control.
What leans the mixture at altitude?

Also, no carb heat (on many aircraft). How do you deal with carb ice?

My 912 has carb heat.

Jay Maynard wrote:
On 2008-01-21, Jim Stewart wrote:
On the plus side, plugs cost $3/each and it only takes an hour to do plugs
and oil.

Yeah, but will I have to take it to my nearest Rotax service center to get
that done?

Nope, a one hour job to do it yourself.
I did mine a couple weeks ago. All you
need is a flat-blade screwdriver to get
the cowls off, a wrench for the plugs,
oil drain and magnetic plug and a pair
of safety wire pliers. Feeler gauges to
check the plug gaps and some anti-seize
compound doesn't hurt either.

2000 RPM idle is fine. 2500 is good for warmup.

The comment I got a few times was that idling below 2500 will eventually
result in a broken crank.

My tach is red-banded below 1800 rpm, and yellow
between 1800 and 2000. Running below 1800
for extended time will shorten the life of the
reduction gears. Never heard anything about
broken cranks.

Pluses for the Rotax are no thermal shock issues,

Why not?

Liquid coolant in the heads.

will allegedly run for 30 minutes at 50% power with either oil or coolant
gone, and 5 gallon/hr cruise.

As opposed to 5.5 in the O-200. That's a negligible difference.

Cruise might be, but how long can the O-200
run without oil pressure? This, btw was a
major selling point for me. The common wisdom
with a 912 is that a coolant or lube failure
will still let you fly to a developed airport
and land. The engine might need a rebuild,
but it will keep running and develop at least
partial power.

No mixture control.

What leans the mixture at altitude?

The carbs.

As for support, I've had no problems with my 912 so I don't have any
direct experience. I know that the west coast FlightDesign distributer
has worked closely with Rotax on some safety directive issues and has
gotten parts and support quickly.

If I break a crank, or blow a jug, how long will it take to get parts? I was
told that people are waitiing 6 months for jugs because Rotax is putting all
it can make on new engines.

Can't answer to that. Everyone I know that
has a 912 has had no problems with it.

Call up Lockwood or Airwolf and ask them how
often they sell a crank or a cylinder. Then
ask how long it takes to get one.

"Thomas Borchert" wrote in message
...
Morgans,

I WILL NOT ever EVER put my but in the air with a Rotax providing the
power.

Period.


Yeah, mass crankshaft recalls and mid-time overhauls are just great!

--
Thomas Borchert (EDDH)

As compared to this:

From AvWeb
Rotax Gearbox MSB Issued
Rotax has issued a manadatory service bulletin affecting specific 912 and
914-series engine gearboxes after a fault was found with the material used
in making the gears. Under severe operating conditions, it's possible for
gear teeth to break. The fix calls for replacement of the gears but the good
news is that Rotax is paying the shot. Removal and replacement of the
gearbox, the gear set and the installation of the new gears is all covered,
as is the freight. This is a significant test of Rotax's constantly
expanding service and supply network as its engines flood the mainstream
aviation network, particularly in the U.S., thanks to the burgeoning
popularity of the Light Sport Aircraft category. The MSB comes two weeks
before the Sport Aviation Expo in Sebring, Fla. where about 80 percent of
the aircraft will be Rotax-powered and their owners and manufacturers ready
to give feedback.
--

*H. Allen Smith*
WACO - We are all here, because we are not all there.