>>>>You just don't purge anything when changing oil on a Rotax : drain the
oil tank, put a new seal and filter, and pour fresh oil. We installed a
quick drain valve so the total time for an oil change is about 10
minutes including removing and reinstalling the cowling.<<<<
Hello Giles,
It might behoove you to take a look at the Rotax Service Instruction on
the 912 that came out last March (2009) regarding oil changes. Specifically,
SI-912-10R3 dated March 19, 2009. This SI runs concurrent with SI 912-018
entitled "Purging of Lubrication System" In SI 912-018, it specifically
describes how to purge the oil system when changing the oil in a 912/914 to
remove old oil and then how to rebleed the system with new oil. Doing this
procedures ensures that the journals, bearings, rocker arms, etc are all
properly lubricated prior to start up after the oil change. SI 912-010 R3
reiterates this method because so many Rotax 912/914 owners have not been
following the proper oil change procedure and bearing failures, among other
things, have resulted. Kerry down at Lockwood in Florida told me that if you
aren't doing this procedure "you are asking for trouble". There is a similar
SI issued for the 914 with the same date. Some people refer to this
procedure as "burping the engine" because of the noise it makes when you are
purging. You can simply drain the oil from the tank, change the filter and
refill
with new oil, but you are leaving nearly a quart of old oil in the engine
and lines if you do it that way. I'm not that familiar with the 912/914
configuration as it exists in the Europa, but that is nearly 1/3rd of the oil
in my Ximango 912S oil system. Leaving 1/3rd of tht old oil in the lines
and engine kind of defeats the purpose of doing an oil change, doesn't it?
>>>>>Any serious engine manufacturer SHOULD issue dozens of SBs, SLs,
etc...<<<<<
Agreed. Rotax does do a fine job of documenting their failures and
resulting maintenance procedures and engine enhancements. This is why I
suggested
to those who repeat the negative rumors about Jabiru engines to do some
reading and understand the history of their Rotax engines. I remember quite
well when the first 912's came out. They were much better boat anchors than
airplane engines. Rotax had all sorts of problems with it, but it has been
so long that many might not remember or be aware. My point was the 912/914
platform has it's own sorted history of failures and those failures continue
to this day if you don't follow Rotax maintenance procedures to the
letter.
The way the Jabiru engine is spoken of here on this forum it's as if it is
the only aircraft engine ever built that has had some growing pains after
initial release. Many here seem to think those growing pains suffered in
the early engines have not been corrected and as a result they are not
reliable engines. Nothing could be farther from the truth. The Jabiru engine
continues to be refined, just like the Rotax 912/914 and it has proven to be at
least as reliable as the Rotax, if not more so because it is so simple,
but, as with any aircraft engine you have to tune it for your airframe for
best results.
>>>>Lord Hives, manager of Rolls-Royce during the war said to Franck
Whittle
: "Give us your jet engine project, and we will soon design the
simplicity out of it ";-)
The early Jabiru were simple, but with time, they now have many many
more parts : hydraulic lifters, cam follower, crankshaft dowels,
etc...<<<<<
The Jabiru USA folks spent about 2 hours the first day of the 3 day class
going over the design goals of the engine, it's history, and all the
refinements that have been done to the Jabiru 2200 and 3300 since they were
released and why. They spent another couple of hours going over the various
failures that they have seen over the years and why they happened, including
passing around the actual failed parts for inspection. In nearly every
incident covered it was operator error that caused the failure. It was quite a
history lesson and a shame that all the naysayers here couldn't have listened
to the lecture and educate themselves.
As far as the refinements that have been done to the Jabiru line of
engines, the hydraulic lifters were developed to reduce maintenance, primarily
for flight schools who use aircraft with the Jabiru engine. IOW, eliminating
the need to adjust the valves every 50 hours as with the solid lifter
version. I seem to recall them saying that overall, parts were removed, not
added
to achieve this enhancement. Not sure what you mean by cam followers.
They're in my engine and every other one of the half dozen or so engines I saw
disassembled during the Jabiru course. Perhaps the early Jabiru engines
didn't have cam followers?
Similarly, I'm not sure how you can look at the innards of a Rotax 912 and
the way the crank is supported, then compare it to a Jabiru and say the
Jabiru is "lightly built". Have you ever seen a 3300 with the case split?
There are seven (7) crank support bearings in the Jabiru, one on each end, and
one between each connecting rod. The Jabiru is built like a tank compared
to the 912/914, or more appropriately, built like a Lycoming, Franklin or
Continental. Compare that to the three crank support bearings in the Rotax
912/914, coupled to high compression pistons and an engine that isn't all
that well balanced and ????. This weak support of the crank is directly
related to the high number of crank and case failures that have happened with
the 912/914. Rotax also had a bad run of cranks out for a while about 10
years ago. One guy who used to keep a 914 powered Katana motorglider at my
field had one.
The crank/flywheel dowels were a response to reported failures in the
flywheel attachment bolts on a limited number of aircraft. To my knowledge, none
of the flywheel bolt failures caused any accidents or forced landings, but
rather were found during routine inspection. This flywheel bolt issue
later turned out to be limited to engines that had sustained unreported prop
strikes. I was told at the Jabiru seminar that there have been no reported
failures of the flywheel bolts on any engines except those that had sustained
prop strikes, but the dowel pins were a good idea, especially if you are
going to run a heavy, unapproved prop, like an MT. So, they were added to
new engines and to engines that are sent back to the factory for overhaul.
Makes perfect sense to me and certainly doesn't overly complicate the engine
at all.
The Jabiru 3300 is one of the simplest four stroke engines I've ever seen.
I've handled every part in a 3300 and assembled one piece by piece from
the case up. I don't know how you could make a four stroke engine any
simpler. Simple is a good thing when it comes to an aircraft engine, IMHO.
Everything about the 3300 is well thought out and made as simple as is humanly
possible. The machining is top notch. Both the 2200 and 3300 continue to be
refined to this day as the fleet hours increase and maintenance issues reveal
themselves, just like Rotax engines. The 912, by comparison, is off the
scale in terms of complexity, IMO. All that stuff is just more that can go
wrong.
>>>>>Many owners are afraid of the maze of coolant lines on a Rotax. But
your
car has many of them too, albeit better concealed from view. And yet
would one say car engines are unreliable ?<<<<<
Depends on the car manufacturer. A Ford, Toyota, or Honda? Very reliable.
A Fiat, Yugo, or GM? Not so much.
>>>>>What counts for an aero engines, is the thousands of operating hours
to
make it reliable, not this or that mechanical choice (as long as it is a
sound choice).<<<<<<
Yep, and the fleet hours of the Jabiru 2200/3300 continue to climb with
every passing day, but you must also realize that Rotax has a 10-12 year head
start on Jabiru. Give 'em some time. They're working as fast as they can to
replace Rotax as the engine of choice in sport aviation. There are now
several thousand of these engines flying world wide in a wide range of
aircraft, both certified and noncertified. Jabiru will continue to sell this
fine
little engine in large numbers because it works well, it's simple, powerful
and the engine and the basic replaceable parts, as well as major engine
components, are considerably cheaper than Rotax engines and parts. This was
one of the design goals of Jabiru, build an engine with as many common parts
as possible to keep the initial purchase price and maintenance costs down.
I believe they have succeeded. Initially, Jabiru's original intent was to
only build engines for their own line of aircraft, but outside demand for
the engine became overwhelming and they have been selling engines outright
for use in non-Jabiru airframes.
>>>>Think of us poor pilots in densely populated Europe. We must overfly
thousands of people, and they don't like noise !
Rotax engines can be very quiet with their slow turning props.<<<<<
Yes, I've been to Europe many times and I'm aware of the restrictions
placed on you by your nanny state governments. My Jabiru 3300, at take off
power, was measured at 71 dB from 100 yards off the runway. My neighbor's
Husqvarna lawn mower measured minutes later at a distance of 230 yards was
measured at 89 dB. My Ximango 912S spinning a Hoffman prop was measured later
that same day using the same dB meter under nearly identical conditions at
take off power at 75 dB at 100 yards. I don't know what Jabiru's you are
listening to, perhaps one with straight pipes and no muffler? Mine is very
quiet, yet the noise it does make is a deep, throaty sound similar to a
Beechcraft. I much prefer a low, throaty sound to the high pitched Rotax whine.
Prop noise isn't a problem, either, when the engine is tuned for the airframe.
At take off load you should only see 2800-2900 RPM. When I hear an
airplane go over I can tell instantly from inside the hangar with the doors
closed
if it has a Rotax or not. The Rotax whine is piercing to my ears.
Oh, and regarding radial engines, you know they aren't really a portable
oil leak, they just like to mark their territory.....
Regards,
John Lawton
Whitwell, TN (TN89)
N245E - Flying
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