Jabiru mixture

spacesailor · April 11, 2019

Not as much as a McCulloch motor. But it was designed for the military,

spacesailor

Jaba-who · April 11, 2019

I agree on the airframe - top little aircraft BUT the engine !!??
Its great to support your motivation type but lets not get too carried away.

Reliability ? This sounds like you have been subjected to some pretty intensive mind altering the therapy - I strongly doubt that, across the Jab engine fleet, their reliability can be compared to LyCon & Rotax.

As for cost: Yep ! they are a lot of engine for the purchase dollar but as with most things in life there is a down/flip side - you then pay in on going higher operating costs (save now pay later).

Well actually he’s not quite as statistically out as you first surmise.

If you recall CASA used figures ( dodgy I admit but they used these in their imposing restrictions and repeated the broad estimations to the senate estimate hearing.

These were:

40 engine failures or major mechanical problems and this equated to 2.6 per 10000 hours of flight.

Their total figures for rotax were 1.5 per 10000 hours and LyCon at 0.8.

On these figures the imposed the restrictions as they stated that they considered anything over 1.0 unacceptable - but oddly did not impose any on Rotax.

But when the figures were pulled out under FOI laws and were looked at it turned out that only about 12 (as best I recall) were real problems all the others were fuel issues, other non engine component failures and several were flights into controlled airspace without clearance! etc (as we are all pretty much aware)

So the real jab numbers went down to approximately a third of the published numbers (12/40) so in fact it was a bit over a third of 2.6 - let’s say 0.8 or 0.9! On a par with LyCon (if the numbers were correct - which they undoubtedly were NOT Because CASA got them without them from the RAAAus without them being carefully acquired. But still they clearly were NO WHERE near the figures CASA used. Why were they believed by CASA - a huge observer bias where they happily ignored the events happening with other engines and noisily beat their chests about the jab ones.

The LyCon figures are more likely to be correct being mostly GA where things are reported more accurately, but just like the Jab numbers being probably wrong so were the Rotax figuresbut CASA were happy to use them because they appeared to show Jabs in a bad light.

So all up we have no correct numbers but clearly the jab figures are no where as bad as people claimed and on the figures available actually yep- they are broadly comparable to LyCons and Rotaxes.

Bald Eagle · April 11, 2019

Not sure who or what have you the idea they are testing the engines for Jabiru.
Thats just bollocks.

Jabba - hut, it’s a known flyin school and as I have a Jabiru I could see the diference in engines and I was told it was a Jen 4 proto type.

I guess the Jab enginering department approved it.

So it’s not BOLLOCKS

ova to you

Jaba-who · April 11, 2019

Jabba - hut, it’s a known flyin school and as I have a Jabiru I could see the diference in engines and I was told it was a Jen 4 proto type.
I guess the Jab enginering department approved it.

So it’s not BOLLOCKS

ova to you

The Gen 4 engines are in production and have been for more than a year. You can buy one now off the shelf. They aren’t in any form of development or test phase. ( beyond the continual assessment and upgrades that all engines go through where if a problem surfaces they come up with changes.

Just because it’s not the same as yours or because it was an early engine doesn’t mean it’s a test engine or they are using it as an experiment on the students of the school as trial engine.

Bald Eagle · April 11, 2019

The Gen 4 engines are in production and have been for more than a year. You can buy one now off the shelf. They aren’t in any form of development or test phase. ( beyond the continual assessment and upgrades that all engines go through where if a problem surfaces they come up with changes.
Just because it’s not the same as yours or because it was an early engine doesn’t mean it’s a test engine or they are using it as an experiment on the students of the school as trial engine.

Jaba, this was probably a ova a year ago and I could not buy an engine, I couldn’t even buy parts for my blown up jab engine, I needed new heads and Jab couldn’t supply these so was told I’d have to wait for a new head supplier or go on a waiting list for a new engine that was to be called gen4.

this flying school engine was a engine you could not yet buy so us students were testing them for Jabiru, weather it was approved, certified or wat Eva by jabiru, it was a new proto type engine, being tested by students !!!!

shame on Mr Jabiru

skippydiesel · April 11, 2019

Well actually he’s not quite as statistically out as you first surmise.
..........................................................................................................................................................................................................................................................

So all up we have no correct numbers but clearly the jab figures are no where as bad as people claimed and on the figures available actually yep- they are broadly comparable to LyCons and Rotaxes.

Well Jaba lets deal with a fact or two -

My Rotax 912 ULS contains 3 L of oil, which I change at 50 hr intervals. I have never had to add oil between services in its 850 + hours to date.
It uses about 12 L /hr @ 100 knots, can loiter at 60 knots consuming about 8 L/hr and if I ask it, it will do 120 knots on about 17 L/hr. It prefers ULP but at a pinch can dine on AvGas.
It is smooth running and quiet (compared with even a lawn mower, let alone almost every other aircraft engine).
Its seems to deliver power without effort, from sea level to 10,000 ft (my legal limit).
I did have to replace the "sprag clutch" probably from using under-powered battery's but other than this the engine has never been opened and only routine service items replaced.
I expect it to be still motivating my aircraft at 2000 + hrs. "on condition")

How goes your Jab?

Jaba-who · April 11, 2019

Well Jaba lets deal with a fact or two -

My Rotax 912 ULS contains 3 L of oil, which I change at 50 hr intervals. I have never had to add oil between services in its 850 + hours to date.

It uses about 12 L /hr @ 100 knots, can loiter at 60 knots consuming about 8 L/hr and if I ask it, it will do 120 knots on about 17 L/hr. It prefers ULP but at a pinch can dine on AvGas.

It is smooth running and quiet (compared with even a lawn mower, let alone almost every other aircraft engine).

Its seems to deliver power without effort, from sea level to 10,000 ft (my legal limit).

I did have to replace the "sprag clutch" probably from using under-powered battery's but other than this the engine has never been opened and only routine service items replaced.

I expect it to be still motivating my aircraft at 2000 + hrs. "on condition")

How goes your Jab?

Uuhhhmmm?

Che??

The figures i was quoting and which were clearly explained were reliability figures as mentioned initially. figures associated specifically with engine malfunctions as used by CASA.

At no time was I, nor will I, compare the types of things you have outlined.

skippydiesel · April 12, 2019

Uuhhhmmm?
Che??

The figures i was quoting and which were clearly explained were reliability figures as mentioned initially. figures associated specifically with engine malfunctions as used by CASA.

At no time was I, nor will I, compare the types of things you have outlined.

Fair enough - the items I have mentioned go to running cost. I believe/hope that what is lost in purchase price, is made up somewhat in running cost.

Also I understand (meaning I dont know for a fact) that most Jab engines will be rebuilt , at least in part, well under 1000hrs - should this be true the initial advantageous purchase price will considerably eroded by this cost.

Also again - if Jab engines do in fact require surgery at such low hours, this would put reliability claims in doubt - what say you??

Jaba-who · April 12, 2019

Fair enough - the items I have mentioned go to running cost. I believe/hope that what is lost in purchase price, is made up somewhat in running cost.
Also I understand (meaning I dont know for a fact) that most Jab engines will be rebuilt , at least in part, well under 1000hrs - should this be true the initial advantageous purchase price will considerably eroded by this cost.

Also again - if Jab engines do in fact require surgery at such low hours, this would put reliability claims in doubt - what say you??

Until you present statistical evidence of that - ie that most Jab engines will be rebuilt at well under a 1000 hours - you can’t say it.

I can say that it’s not correct in our flying group. We’ve had five engines over about 10 years in 3 aircraft. One of them had a single cylinder head replaced and then two were replaced because it was cheaper to replace the whole engine then to upgrade to the new pistons and roller cams.

In the whole Jabiru world - I don’t know.

What has been proved is there’s a wide expanse of observer bias in the aviation world. ( not just with Jabiru)

where individuals get a gut feeling about something and then selectively ignore similar issues in all other brands and fixate and amplify events (or unsupported statements) involving their target.

So statements like yours really do need to be backed up by some statistics before they are made else they just feed more gut feelings and generate a life of their own.

skippydiesel · April 12, 2019

All true - that's why I said I did not know for a fact but I do know one of my local flying schools, who operate an exclusively Jab fleet, are veritable experts in rebuilding engines. The other school, powered by Rotax,912's, seem to limit their maintenance to routine services. You can speculate why this may be and come up with a range of answers.

jetjr · April 12, 2019

the certification argument has been Rods excuse for some years, in reality theres only one (very old) Jabiru engine that is "certified", all the rest are ASTM at best and even if it had EFI fitted its up to Jabiru to back its operation or not. Was always the excuse that it brings in failure modes and makes engine reliant on electrical system.

SDS have a setup which works well and some here have carb retained as in flight redundancy - works great Im told. No individual injector trim for 6 cyl unless you get dual ECU which makes it pretty expensive. Several flying well here and fuel savings alone see it stack up over pretty short time.

South Africans had a really nice EFI setup and sold some but AU put a stop to it.

Jabiru have a tendancy to promote and approve only things they own or have developed in house. An understandable business model but restricts development to their own capabilities and opinions.

spacesailor · April 12, 2019

Skippydiesel

"Well Jaba lets deal with a fact or two -

My Rotax 912 ULS contains 3 L of oil, which I change at 50 hr intervals. I have never had to add oil between services in its 850 + hours to date.

It uses about 12 L /hr @ 100 knots, can loiter at 60 knots consuming about 8 L/hr and if I ask it, it will do 120 knots on about 17 L/hr. It prefers ULP but at a pinch can dine on AvGas.

It is smooth running and quiet (compared with even a lawn mower, let alone almost every other aircraft engine).

Its seems to deliver power without effort, from sea level to 10,000 ft (my legal limit).

I did have to replace the "sprag clutch" probably from using under-powered battery's but other than this the engine has never been opened and only routine service items replaced.

I expect it to be still motivating my aircraft at 2000 + hrs. "on condition"

Thats good

How about

500 ml oil.

6 litres an hour fuel consumption, at 100 mmph, VNE 140. (in a dive)

SHAKIEST of all the motors.

All of 35 HP (Hand-cranked ).

spacesailor

Old Koreelah · April 12, 2019

...I understand (meaning I dont know for a fact) that most Jab engines will be rebuilt , at least in part, well under 1000hrs - should this be true the initial advantageous purchase price will considerably eroded by this cost...

If true, that might be a factor for those who clock up lots of hours. Many of us don't. My plane has had a Jab engine for over a decade and it's got less than 200 hours up and is cheap to run.

At this rate, my Jab engine, bought for half the price a Rotax, should see me out...

turboplanner · April 12, 2019

Nothing is ever " at owners risk".
There will always be a vulturous lawyer and an easily manipulated widow when these things go pear shaped. It's amazing how the law so easily removes all fault from the dead victim and transfers it the living - especially if the living have deep pockets or are perceived to have deep pockets.

And they would have every legal reason to pounce if there was a sub standard assuming fitted, when the benchmark required a higher standard of design and testing.

Bald Eagle · April 12, 2019

Until you present statistical evidence of that - ie that most Jab engines will be rebuilt at well under a 1000 hours - you can’t say it.
I can say that it’s not correct in our flying group. We’ve had five engines over about 10 years in 3 aircraft. One of them had a single cylinder head replaced and then two were replaced because it was cheaper to replace the whole engine then to upgrade to the new pistons and roller cams.

Jaba, have a look at all the secondhand Jabirus for sale, most of the engine hours never match the airframe hours, and never seem to get more than 400 hours before a rebuild, look at all the Rotax powered tecnam’s, gazelles, ther engine hours usually match the airframe hours.

Thruster88 · April 12, 2019

Jaba, have a look at all the secondhand Jabirus for sale, most of the engine hours never match the airframe hours, and never seem to get more than 400 hours before a rebuild, look at all the Rotax powered tecnam’s, gazelles, ther engine hours usually match the airframe hours.

Bald Eagle, you and I are just suffering from "observer bias in the aviation world"?

Bald Eagle · April 12, 2019

Gidday thruster, I think we are not the only ones that have noticed this.

my Jabby is on its third engine in less than a 1000 hours and the previous owner put in no incident reports so as to not rock the boat. The first engine I believe dropped a valve and a replacement overhaul engine was offered at a very good price, the replacement engine was short lived and had sum serious unknown, un documented problem so an another engine was offered at a much reduced price so why would you dob in a mate that is trying to help and I think this is how jabiru managed to cover up and fudge figures.

we all want this all Australian company to do well, the airframes are excellent but sadly the engines do have reliability issues.

remember when that lean burn carby kit was released, all the engine failures.

Now tell me this, who were the test bunny’s for this engine ?

Was it ever factory tested ?

This new gen 4 engine, what and who was the factory test program before being released for use in aeroplanes ?

Was it certain flying schools ?

Ova to u blokes

Jaba-who · April 12, 2019

Jaba, have a look at all the secondhand Jabirus for sale, most of the engine hours never match the airframe hours, and never seem to get more than 400 hours before a rebuild, look at all the Rotax powered tecnam’s, gazelles, ther engine hours usually match the airframe hours.

We’ve been through these horsefeathers argument so many times I shouldn’t even respond. I promise this will be the last one ?

many aircraft of many types change engines for reasons other than a failed engine.

Jabiru in particular have brought out 4 generations with multiple changes within these generations. Each time they have offered upgrades ( at significant cost) or trade ins on old generations. It’s been cheaper ( or equal cost) to get a whole new engine. - I did this with my gen 2 at 550 hours when I wanted to upgrade to the new roller cams and the new recessed pistons. Exact same $ to get a new one in a box within a week or wait 3 months for the old one to be upgraded. No brainer.

Have heard of flying school who rather than overhaul their engines at 1000 hrs just changed them for a new one.

Prop strike - if you have a few year old engine. Instead of all the tests and X-rays upgrading to a new one is a sensible option considering how cheap they are.

Its been long stated many many times that until you get the detail at every individual with an engine-airframe time discrepancy you can not draw any conclusions as to the reason for that discrepancy.

turboplanner · April 12, 2019

No single carb system delivers even fuel mixture to all cylinders. Even lycos and conts have uneven distribution. It’s just that they don’t measure it on most aircraft so you don’t know it, and they are big heavy cylinders which handle heat better so the cylinders don’t fail as much ( but still plenty do. ) if they are uneven so there isn’t the effort put to sort out uneven distribution cos it’s not as important. But jabs are really light, don’t have the heat sink capability of a massive amount of metal etc. so distribution becomes more important and more of us monitor  every cylinder for both CHT and EGT.

Yenn - you are conflating two different issues. The carby is not unreliable and it’s reliability and function is not affected or changed by the fuel control unit they’ve come up with.

The carby does its bit more or less as its supposed to ( but personally I reckon it does it as marked but it’s a crap idea and I have long wished I had a normal carby that I could control leaning etc but that’s a different story. )

But the new control  unit does all its stuff downstream of the carby and basically makes up for fact the mechanical pathway ( not the carby) stuffs up the work of the carby. It would be just fine if we had it feeding just one cylinder.

What concerns me with the new system is it seems - maybe I’m wrong - that it relies on some cylinders running rich and then leans them match the leaner ones.

Wonder how we deal with situation where none are rich ( they’re just right say) and some are already lean. Then it leans out the just right ones  too make them lean to match the lean one.

So now you run them all lean.

So then you have to rejet the carby. Bigger job pulling carby out put it back retest it pull it out again if needed.

Big job.

If you run them all too lean you get upper cylinder failures. Uneven mixture in many engines is solved by the logical solution of using different jet sizes.

If all jets are right, i.e. delivering the correct mixture to each cylinder chamber, as physically measured then you don't need an add on accessory.

kgwilson · April 12, 2019

When the ATSB released its interim reliability report in 2014 Jabiru failure rates were somewhat higher than Rotax. Interestingly due to continuous improvement the Jabiru rate decreased and the Rotax rate increased by the time the final report was published.

ALL engines have their problems and modifications and upgrades are done to rectify these. Continental & Lycoming have been around for many more years than Jabiru and the failures and faults have been met with appropriate mods and upgrades just as Jabiru and indeed Rotax have. I have a Gen 3 3300A & don't know of any failures of this model. Many of the original issues (other than the well publicised through bolt, valve sticking and gudgeon pin circlip issues) originated from poor maintenance routines & the failure to treat the engine like an aero engine. A theory of mine is that Jabiru opened up aviation to many who had always thought the cost prohibitive but then they failed to understand that you can't treat a lightweight air cooled aero engine like a car engine. The Rotax on the other hand with its partial liquid cooling and Skidoo origins is more forgiving to poor treatment as well as having had a lengthy development period to sort out the bugs. Rotax though also has issues, is far more complex and requires plenty of attention to it's extensive plumbing.

It is your choice as to what engine you fly behind. I am more than happy with mine. I can fly all day a full throttle if I wish. Rotax is a maximum of 5 minutes. Cost was 20K installed compared with 35k plus for the Rotax with 20 less HP. Our local school has always maintained its engines strictly in accordance with the Jabiru manual. The first engine had a top end done at 1000 hours & replaced a 2000 as it was cheaper & quicker than an overhaul. The second was traded on a new one at 1000 hours when it was due for the top end because the overall cost of ownership was less.

turboplanner · April 13, 2019

If you recall CASA used figures ( dodgy I admit but they used these in their imposing restrictions and repeated the broad estimations to the senate estimate hearing.
These were:

40 engine failures or major mechanical problems and this equated to 2.6 per 10000 hours of flight.

A simple definition of a Senate Estimates Hearing is that it is "to allow Senators to scrutinise how executive government is spending taxpayers money".

One Senator asked leave of the Chairman to ask a question, and ambushed the DAS with a prepared question. The DAS took advice from an advisor and gave the answer based on a report requested at short notice, supplied with obviously incorrect numbers which included flat tyres, running out of fuel etc. and had been used by the public relations officer (as against the people relevant to the instrument). The Senator was admonished by the Chairman for taking up time and the matter sank like a stone, and we should all discount that obviously incorrect list of 40 failures in one year.

A Senate Inquiry would be another matter; this is where there is a perceived issue and people can be compelled to appear and provide evidence under oath.

Current Senate Inquiries include:

Performance of the Australian Maritime Safety Authority
The provision of rescue, fire fighting and emergency response at Australian Airports

An off the cuff question from a Senator at an estimates hearing does not have the status of a question at a Senate Inquiry.

Routine mechanical failures which don't lead to forced landings, are not safety related, and if they are more frequent on one engine than another, the issue becomes the cost of operating the engine, and operators will tend to resolve that themselves in the marketplace by buying the lower cost of life product.

On the other hand, mechanical failures leading to forced landing introduce the possibility of occupants being injured or killed, and there are many cases where pilots have stuffed up what should have been successful forced landings. That's where action by the Safety Authority may be required.

In your other posts you were looking for people to quote provable figures, so here's a list:

Source: RAA Magazine

Period: 62 months from Feb 2007 to March 2012

All cases were either forced landings or "landings" where the aircraft was not in a position to take off again.

Engines: Jabiru and Rotax 912 series

Jabiru

Broken crankshaft 1

Thru Bolt 11

Exhaust failure 16

Conrod failure 1

Cylinder crack 2

Retaining stud failure 1

Seized 3

Power loss 2

Cracked cylinder head 1

Catastrophic engine failure 1

Misfire and shudder 1

Total 40 failures

Rotax

Engine failure

Circlip

Oil pressure

Vapour lock

Carbs overflowing

Oil leaking around filter

Spark plug fell out

Total 7 failures

Their total figures for rotax were 1.5 per 10000 hours and LyCon at 0.8.

Perhaps you could use your own standards, and tell us whether you can find any forced landings due to mechanical failures of either Lycoming or Continental failures during this period?

(if the numbers were correct - which they undoubtedly were NOT Because CASA got them without them from the RAAAus without them being carefully acquired. But still they clearly were NO WHERE near the figures CASA used. Why were they believed by CASA - a huge observer bias where they happily ignored the events happening with other engines and noisily beat their chests about the jab ones.

What we do know is that two CASA employees went in to RAA and obtained the engine figures they worked on, and you could get the truth just by contacting Lee Ungermann or Mick Poole.

My observation is that Jabiru designed a new engine, and reports of forced landings have virtually evaporated. If anyone with a Jabiru was concerned about their old engine they can fit a new one and still be ahead on cost compared to someone who bought a Rotax.

This thread is supposed to be about an accessory offered by Jabiru.

kgwilson · April 13, 2019

Thread drift including Jabiru bashing yet again.

facthunter · April 13, 2019

We are are going over old ground. Jabiru and other engines are used under a lot of varying conditions some of which are far from ideal. The engine to airframe hours thing has been explained many times. That's a case of a good deal being used against the motor's reputation. Not a true representation of reality and a bit unfair. TBO is for the major engine itself, and some claimed TBO's are fanciful. Top end work is particularly likely in little used engines or where overheating is likely due to installation or type of use. Bore corrosionand valve stem stretching etc. Steel bores not used regularly will corrode and require proper inhibiting to prevent problems affecting reliability. I know of no one doing this properly and where many planes just sit for weeks or months dangerous corrosion is likely.. I would NEVER expect a jabiru to go the full 2000 hours without head work nor would I expect any aircooled motor to do it. Some inspections can only be done properly with part of the engine dismantled. The well respect Gypsy Major generally had head work done by 500 hours. Some expensive motors have low TBO's

On another note the Superior (one model (stroked crank) used in some RV's has been recalled.) that's an indication not all motors just go forever. An aero engine is not a "fit and forget" item and never will be until they are all electric. Inspect and check is the go applied as needed to any engine. No engine is absolutely reliable and the Rotax is not as reliable as it was when they were all 80 Hp and NEW. Nev

skippydiesel · April 13, 2019

Turboplanner

".................................................................................

If anyone with a Jabiru was concerned about their old engine they can fit a new one and still be ahead on cost compared to someone who bought a Rotax.

...........................................................................................".

You got to be kidding me - 2 Jabs for under the price of one equivalent hp Rotax !!!!!!!!

Kgwilson

"Thread drift including Jabiru bashing yet again."

Well thread drift is where the respondents go, so why not?

Jab bashing - cant speak for others but in my case, I am admirer of the Jab aircraft/airfame, particularly more recent iterations BUT unless there has been a recent & radical change, the engine is an issue, no getting away from it, no matter how loyal you are. If you are only flying in the training area/circuits, a few hours per year and avoiding Tiger Country completely, a Jab engine is a very cost effective option - nothing wrong with that. If the converse should be true, most other aircraft engines are, from my perspective, a better bet and may in the long run (hours) be just as cost effective or more so. I take all this back if Jab have made the aforementioned radical changes, however it will take time to undo the bad rap.

The market place reflects peoples "pockets" and their mission objectives not necessarily the quality of a product.

turboplanner · April 13, 2019

We are are going over old ground. Jabiru and other engines are used under a lot of varying conditions some of which are far from ideal. The engine to airframe hours thing has been explained many times. That's a case of a good deal being used against the motor's reputation. Not a true representation of reality and a bit unfair. TBO is for the major engine itself, and some claimed TBO's are fanciful. Top end work is particularly likely in little used engines or where overheating is likely due to installation or type of use. Bore corrosionand valve stem stretching etc. Steel bores not used regularly will corrode and require proper inhibiting to prevent problems affecting reliability. I know of no one doing this properly and where many planes just sit for weeks or months dangerous corrosion is likely.. I would NEVER expect a jabiru to go the full 2000 hours without head work nor would I expect any aircooled motor to do it. Some inspections can only be done properly with part of the engine dismantled. The well respect Gypsy Major generally had head work done by 500 hours. Some expensive motors have low TBO's
On another note the Superior (one model (stroked crank) used in some RV's has been recalled.) that's an indication not all motors just go forever. An aero engine is not a "fit and forget" item and never will be until they are all electric. Inspect and check is the go applied as needed to any engine. No engine is absolutely reliable and the Rotax is not as reliable as it was when they were all 80 Hp and NEW. Nev

Forget the engines; what are your thoughts on the Automotive Mixture Control System? There's a description and a mockup here: https://jabiru.net.au/ Scroll down the main page.

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