Jabiru engine life times

[Jabiru7252]

Since the Jab heads were billet, last time I looked

What on Erath does that mean?

 

 

[Bob Llewellyn]

foxy said: Ive found that she ran a little smoother when running on 98 octane fuel than when she was run on unleaded.That's in line with expectations. Lead is the best lubricant but it also fouls engines.

100LL is Iso-Octane (tri-methyl pentane, I forget the locations) with TEL added; ULP is parafins plus aromatics plus - for the high "octane" stuff - some unstable organo-metallic; the two would have fairly different time-temperature diagrams when burning, and one would reasonably expect the more complex blend to burn in several stages (even though it's all over in a few milliseconds, the rate of pressure rise is crucial to "smoothness', and has a bit to do with achieved TBO...

 

 

[Bob Llewellyn]

What on Erath does that mean?

They ain't castings, they're machined from solid wrought bar/plate al...

 

 

[Bob Llewellyn]

I have read this post a few times but cannot make sense of it. Obviously I have had a mini-stroke and need to have a Bex and a lie down. Does it read 'right' to others out there? Will check in tomorrow for responses and abuse.

Sorry, I'm writing like it's a conversation. Ok - as oils get hotter, they get runnier. Methyl Silicone stays unrunny to higher temperatures than parafin, or "mineral", oils. So, all other things being equal, in a hot location the Methyl Silicone will be slimier. But all things ain't equal! Under high pressures - like a rocker driving a valve - the local viscosity of any oil gets much higher; Methyl Silicone has ~1.6 times the pressure viscosity coefficient of parafin oils. So, under pressure, Methyl Silicone will be slimier.

It follows that, in a hot cylinder head, Methyl Silicone oil will have far better "lubricity" (sliminess) than oil squeezed out of the ground & refined - i.e. paraffinic oils.

 

Furthermore, when a parafin oil gets too hot, esp in the presence of iron (or steel), it breaks down, releasing carbon particles. These are the mongrels that cause piston ring sticking, and also cause incomplete valve closure as the valve stem tends to bind in the guide (generally also with the formation of lacquers from the disintegrating oil molecules).

 

Methyl Silicones do not start this until considerably hotter than their parafin equivalents.

 

Now, to my eye there is a considerable body of evidence that the valves themselves are generally of acceptable quality - they don't fall to pieces too often - and the valve springs don't turn to melted cheese. This only leaves valve stem binding due to lubricant failure - probably only intermittent, but it starts the valve seats burning - as the probable culprit.

 

As none of the materials used in the jab engines is, in fact, soluble in Methyl Silicone, I cannot see any credible argument against using a better lubricant, aside from that it would probably irritate Rod Stiff.

 

 

[jetjr]

Guys, VERY old thread, most admitted its a poor way to gather data, firstly small sample size then differing opinions on what is considered standard operational maintenance or an engine failure.

 

Theres some more current threads going giving Jabiru a hard time over engine problems - maybe with justification.

 

Re oils, getting off topic and as many are run in LSA which cant vary from Jabiru information.

 

There is work being done to use other Aeroshell aviation oil in Jabiru engines with good results, engines have run big hours on this oil and will soon be torn down and inspected before recommendation changes. Not all good for engines with 100+ hrs. on them.

 

Interested in your ideas on Sport Plus from Aeroshell Bob

 

 

[Jaba-who]

Have to agree with some of the posts. This is a self selecting survey whose design doesn't give any usable information. But the information it could provide is long overdue and necessary.

 

Could it be rejigged to include engines that have had no problems and what times they have got to.

 

Then it would be immediately useful.

 

 

[Bob Llewellyn]

Guys, VERY old thread, most admitted its a poor way to gather data, firstly small sample size then differing opinions on what is considered standard operational maintenance or an engine failure.Theres some more current threads going giving Jabiru a hard time over engine problems - maybe with justification.

Re oils, getting off topic and as many are run in LSA which cant vary from Jabiru information.

 

There is work being done to use other Aeroshell aviation oil in Jabiru engines with good results, engines have run big hours on this oil and will soon be torn down and inspected before recommendation changes. Not all good for engines with 100+ hrs. on them.

 

Interested in your ideas on Sport Plus from Aeroshell Bob

My understanding is that it's all about the interatomic bonds - no, stay with me - "natural" and "synthetic" oils are all based on carbon-carbon structures, with hydrogen around the edges. The three basic stable carbon, um, "backbone" structures are called Paraffinic, Aromatic, and Napthenic. Crude oils contain different blends of these, and some crudes take longer to disintegrate than others - e.g. Pennsylvanian oil stocks were aromatic/napthene rich, and so both stayed slimier for longer as oils, and made higher octane petrols, than early Russian stocks.

However, all natural oils are blends, so some proportion of them (as lubrication oils) breaks down rapidly, and some proportion lasts well. They also have a high vapour pressure, which is not favourable from a foaming aspect.

 

Synthetic oils contain a much more limited range of constituents - although the forms they do contain are also found in nature - which gives an aging curve more like a plateau and cliff, than a bumpy final descent. In fact, if the steel components are cool enough, synthetics can last a remarkably long time. They also have lower vapour pressures than natural oils.

 

So much for carbon. Silicon acts like carbon (in a chemical and micro-structural sense), but it's bond strength is higher. So, silicon-backbone oils last longer st the same temps, or the same time at higher temps; and, being synthesised, can offer the same shape aging curve as synthetic carbon-based oils, to a higher temperature for a longer time. The vapour pressure is also quite low (vapour pressure is not the only determinate of foaming behaviour, but it's the basic one).

 

Shell say "AeroShell Oil Sport Plus 4 is made up of a blend incorporating synthetic technology and high performance additives to help provide long lasting protection.". This says to me, that Aeroshell Sport is a synthetic carbon-based stock, probably with added napthenes separated from natural oils, and some added methyl silicon. It is therefore a bit cheaper to make than straight methyl silicon, does not last as long as straight methyl silicon, and has a higher vapour pressure than methyl silicon. The fact that Shell see fit to advertise a detergent ingredient to clean up carbon deposits shows clearly that the oil is designed to break down; and begs the question, what are the side effects of the disintegrating "detergent action" molecules as the oil ages?

 

Conclusion: Shell have given up, and added a bit of extra methyl silicon to a good grade of car oil, because cars aren't run at WOT / full power for 5 minutes at a time, every drive. It's probably better than the competition, but it's in a lower class - i.e. carbon based - than straight methyl silicon.

 

CAVEAT: I do not know that AMSOIL is straight methyl silicon, but I DO know that the AMSOIL 2-stroke product, run in Rotax 501/503/505s back in the early 80s, resulted in carbon-free piston rings, very pale ash on the piston crown and head, and a film of oil - NOT black carbon - in the exhaust ports.

 

If I find a vendor of an oil that performs as methyl silicon did under NACA test, and costs less than a gonad, I'll tell the world. In the meantime, any oil with an HP additive - for gearboxes - almost certainly has methyl silicon in it, and is therefore a better oil than one without methyl silicon. (Note that gear oils without HP additives, may be assumed to NOT have methyl silicon).

 

 

[Bruce Tuncks]

I've got 450 hours and its running well since I tweaked the cooling ducts and the front cowl. Its never had a breakdown. It did have an overheating problem before this was done . At 200 hours, I replaced the rear cylinder heads with the then latest model bigger-finned heads. That was in 2005 and its run ok since, the compressions are good and its never had an oil-leak.

 

There's nowhere in your table for me to vote because you don't have a box for 450 hours and no breakdown..

 

 

[winsor68]

I hope anyone "tweaking" the design of their Jabiru has 19 rego.

 

 

[Guest Andys@coffs]

My J3300 was a 2005 solid lifter model. At approx. 200hours I suffered low leakdowns (lowest was 30/80) that meant it needed to be repaired.

 

At repair the Jabiru expert maintainer found that:-

 

1) The valve guides were worn out and needed to be replaced. We chose to put K liners in (Yes I'm 19 registered)I'm told this is usual due poor quality originals.

 

2) The bores were corroded at the top of the cylinders and needed to be replaced. Not withstanding the corrosion (which I claim was my issue not Jabiru's) the cylinders were elongated to eggshape rather than round looking top down. So too were the pistons. Im told that this isn't unusual.......

 

3) New pistons and rings needed.

 

The corrosion was my issue but the out of round cylinders and pistons and the valve guides being shagged weren't a function of corrosion. The hours run were very low and IMHO to cut out valve guide in <200hrs was a problem. Oil was W100 W100+ and the 15W50 to try and solve the cold starting issue. I was told W100+ was Ok but 15W50 doesn't last.....but in any event I always changed oil at or before 25hrs of use.

 

I installed 6 x CHT and 6 x EGT gauges when the overhaul was done.

 

I believe that the engine is running too hot today (less than 10hrs from overhaul) as number 3 is running CHT circa 180degrees C. 180 is well under what J say is the max CHT but the repairer say that they need to be much lower than that........Of to Cessnock to see the expert again shortly......and best of all I have to use the inland Maitland lane of entry through tiger country at <1500ft.......

 

The problem with this type of survey is the complexity of the engines. The reality is that we call them all Jabiru engines but over the years they have significantly changed and comparing a solid lifter from 2005 against a high hour engine that came out of the factory in 2013 isn't fair as they are very different beasts. While there are a bunch of AD's on the engine I wonder how many people actually incorporate all the AD's....... I know of some solid lifter 3300 owners who said "Through bolt AD.....Bugger off not happening fixes a non existent problem for my engine" Yet most 2200 owners wouldn't be keen to avoid the through bolt AD.....

 

Andy

 

 

[Bruce Tuncks]

Yep I do have a 19 plane. But its really hard for me to accept that improving the cooling could be illegal.

 

I have all 4 CHT's being measured and I've dropped them 15 degrees or so. Why on earth would they want to stop you doing this?

 

 

[Jabiru7252]

As a few of us sat around at the club house with a beer or two I said "There goes a man who knows his cylinder head temperatures" as you roared your mighty jab into the hot afternoon air. The others nodded their heads in agreement while sipping their respective ales...

 

 

[Bob Llewellyn]

Yep I do have a 19 plane. But its really hard for me to accept that improving the cooling could be illegal.I have all 4 CHT's being measured and I've dropped them 15 degrees or so. Why on earth would they want to stop you doing this?

Anout 10-12 years ago, the FAA said "we do not ensure airworthiness. We ensure that procedures have been followed, that have been shown to deliver airworthiness"... CASA is trying to follow this precept. Now, merely improving the airworthiness of your aircraft is irrelevant to them; if you don't use their specified procedures, you are evil and BAD!!! (nothing personal, just so you know

 

 

[biggles]

Yep I do have a 19 plane. But its really hard for me to accept that improving the cooling could be illegal.I have all 4 CHT's being measured and I've dropped them 15 degrees or so. Why on earth would they want to stop you doing this?

Bruce , what are your temps in normal operation ?

 

Bob

 

 

[Oscar]

Interesting numbers, though somewhat inconclusive for a couple of reasons.

 

Firstly, the total number of votes (including mine) represents about, or probably a bit less than, 3% of the number of Jab. engines currently flying out there. Since Jabiru have produced somethingg like 7,000 engines, of course it's a very small sample indeed. I'm no statistician but I suspect that's not likely to be a useful sample size from which to draw much that indicates a trend.

 

However, probably the more important point is that what is being sought are reports of 'effects': i.e. the ultimate result of a situation, not necessarily the cause. We know that running a Jab. engine too hot / with detonation happening will kill it stone dead very quickly. Consistently running with high CHTs has multiple possible effects leading to a failure, including head warping, valve guide /valve head problems. Detonation will kill the through bolts extremely quickly.

 

We also know that there is a pervasive belief that Jab. engines need to be 'run hard' (though Jabiru have released sufficient information about what is actually meant by 'running hard' i.e. keeping the revs up to around the 2800 rpm mark - NOT 'lugging' the thing at high-power / low speed conditions , to act as a guide to owners and operators about how to best utilise the characteristics of the engines).

 

We also know, from various threads over recent times, that some people have an innate tendency to experiment with fuel and oil - sometimes with considerable reported success, other times probably not. It may be that on average these tend to cancel themselves out: some people, such as Bruce, take a keen interest on 'doing the right thing' by their engine and reap the benefits.

 

We know that Jabiru have at times had QC issues with batches of components, and sometimes that has most certainly caught out some owners before the problem has been identified. Of course, that isn't restricted to Jab. engines, it happens to all manufacturers (witness the Emergency Recall on Rotax crankshafts last year, for example.) I personally think that Jabiru have somewhat more than their fair share of these QC issues and I am certainly not excusing them from that. However, in the main I believe that Jabiru does attempt to rectify these issues when they appear: the initial free replacement of through-bolts that lasted, I think, for nearly two years? is one such example.

 

What is most conspicuously missing from the survey (and I accept that it would make for a far more complicated form of response) is indication of the real causes of these failures. We have seen on the 'Bad Experience with Jabiru' thread an independent report prepared by a very reputable Insurance Assessor that showed clear evidence of very hot running. This was one of two Jab engines (a 3300 and a 2200) owned by one operator that had had problems. One might reasonably assume that there is an operator element in that; by comparison, we have on the same thread a report of multiple Jabs operated by the Murray Bridge club that consistently run 1,000 hours plus without problems. One can, I think, equally assume that those engines are operated within a regime that preserves their life rather than shortens it.

 

I am currently rebuilding an old Jab that had an EFATO (through-bolt failure at about 370 hours) leading to an overturn. This is a 3700+ hour machine that has almost exclusively been used for flying training, and the log books detail several engines that lasted very poorly. Now, in doing the rebuild I have almost completely stripped the entire aircraft chasing any problems so it will be as good as (and in some respects, better than) new; I don't intend to put it back in the air unless I am happy with every last damn detail.

 

In doing that work, I have found a significant number of details that shout 'poor maintenance' - and that maintenance was all, ostensibly at least, done by L2's - certainly signed-off by L2's as required for a training aircraft. I'd like to think that at least some of that work wasn't the fault of any L2 but done by cag-handed operators themselves. When one finds evidence of maintenance work that rivals stuff you might be more likely to see on a cockie's 1980 Hilux ute I don't think it's unreasonable to suspect that not a lot of attention was in all likelihood paid to looking after the engine very carefully, either in terms of maintenance or operation.

 

I don't think that anyone argues that it would not be highly desirable if Jabiru engines were more robust, had a better tolerance to occasional 'hard use' when circumstances (short strip, hot weather, steep-climb out necessary etc.) requires it, nor that there were fewer QC issues. Anybody who does not recognise that Jab engines are a mix of compromises (as is ANY mechanical system) is kidding themselves. In the Jab. case, those compromises are initial cost, weight reduction to improve MTOW in (particularly) of a factory airframe that is extremely robust and simple to repair because it does not use 'exotic' composites, rather good economy figures.

 

Nothing comes for nothing, and the trade-off Jab owners need to consider is that they treat their engine decently. That in itself doesn't, obviously, guarantee against the failure of a poor component that is below par from a QC POV, but it's fairly obvious that expecting the Jab engine to simply take whatever is thrown at it is very poor engine management practice. I'm quite happy to accept that a Jab engine isn't as 'robust' as a Rotax 912/914, and for those who want that level of robustness, then I'd say go buy the Rotax. I'm personally confident that the CAMit improvements will ratch-up the reliability factor for Jab engines by quite a margin, but I'm not going to assume that just because I have them installed in my engine I can happily flog the thing mercilessly.

 

 

[alf jessup]

Oscar,

 

For a CASA certified engine I would have thought it would be more robust than it currently is.

 

Hate to imagine what they would be like if they weren't "certified".

 

I'll stick quite happily to the uncertified robust Rotax engine that gets treated the same as I guess as the poorly maintenance wise pilots who fly behind both Jabiru & Rotax powered aircraft.

 

Sad fact is Rotax doesn't blame the owners or maintainers mainly because they are far superior built and don't fail all that often.

 

Like the old saying goes if you want the oats before they been through the horse you pay a bit more for them (Rotax).

 

Alf

 

 

[motzartmerv]

Thanx for the informative response oscar, this poll was posted over a year ago, so perhaps an updated one would help with accurate figures.

 

The engine report you quoted didnt tell the operator anything new, as they knew it went supernova over a few seconds. The operator has YET to receive an indication as to what caused the sudden over temp.

 

The 2200 engine operated by the same person had 4 channel monitoring of the CHT and EGT for its entire (post factory top end) which clearly showed no over heat event.

 

Further, that same operator that Jabiru (and you , seemingly) seem so quick to offer as a 'reason' maintains other Jabiru engines and rotax engines, with no reportable problems. Out of three Jab engines and 4 rotax engines maintained and operated over the same period by the same people, two engines, (one 2200 and one 3300) have suffered significant component failures. While the third Jab 2200 engine and all the rotax engines have had NO such failures.

 

For the thesis of "the operator and maintainer " being at fault to hold water, this anomaly needs explanation or the thesis can be disregarded.

 

Further to my promise to not offer my 'opinion' on these engines I provide the above as facts only.

 

 

[skeptic36]

You guys might want to read the Q & A at the bottom of this add: http://www.ebay.com.au/itm/Jabiru-230D-Aircraft-/271378057595?pt=AU_Aircraft&hash=item3f2f64897b

 

 

[motzartmerv]

Where is the tongue biting icon..

 

 

[Oscar]

Thanx for the informative response oscar, this poll was posted over a year ago, so perhaps an updated one would help with accurate figures.The engine report you quoted didnt tell the operator anything new, as they knew it went supernova over a few seconds. The operator has YET to receive an indication as to what caused the sudden over temp.

The 2200 engine operated by the same person had 4 channel monitoring of the CHT and EGT for its entire (post factory top end) which clearly showed no over heat event.

 

Further, that same operator that Jabiru (and you , seemingly) seem so quick to offer as a 'reason' maintains other Jabiru engines and rotax engines, with no reportable problems. Out of three Jab engines and 4 rotax engines maintained and operated over the same period by the same people, two engines, (one 2200 and one 3300) have suffered significant component failures. While the third Jab 2200 engine and all the rotax engines have had NO such failures.

 

For the thesis of "the operator and maintainer " being at fault to hold water, this anomaly needs explanation or the thesis can be disregarded.

 

Further to my promise to not offer my 'opinion' on these engines I provide the above as facts only.

Merv, you're more than welcome. I 'll do what I can to add value to any discussion of Jabirus.

 

Now, let me point out that an 'anomaly' by its very definition does not add to the evidence for or against a general thesis so the thesis stands until proven nonviable by actual statistical evidence. Anomalies are not statistical evidence.

 

Am I getting too academic here? - I apologise if I am, but nobody told me I had to leave my intelligence at the door to be a real aviator in the RAA scene. I have to admit that that suggestion has come as somewhat of a surprise to me, as plenty of the RAA people I know don't seem to have any such problems with people using intelligence or even polysyllabic vocabulary. I'll certainly try to leave my education behind if I venture north of the Qld north-south divide, even though I know people in Townsville who can count to ten without using their fingers, and who enjoy things such as Chamber Music festivals and philosophic conversation. If I need to, I'll take up chewing tobacco, spitting and using single-syllable words (or should I call it not using posh language?) if I venture back there. That's going to be a bit hard, even 'Mate' has more than one syllable, but in the interests of good communication, I'll try. My last memory of Townsville is being regarded suspiciously by a barman for trying to buy a bottle of red after 6.00 p.m. on a Saturday evening; I ended up being written about in the local newspaper for having intimidated the same barman.

 

However, having looked at the stats so far produced, it seems to me that somewhere around 34 Jab. owners have responded. That seems to suggest that somewhere more than 1,000 Jab owners are not sufficiently concerned about their engine life to contribute to this forum. My appreciation from contributing to this site is is that something like 20 or so forum members are vehemently opposed to Jabirus, and I frankly think I can be of more use providing what information I can to the other 1,000 plus than fighting with what may well be described as the 'rump' of Jabiru commentators. (see: http://www.oxforddictionaries.com/definition/english/rump , definition 2).

 

So, good luck with your campaign to gather statistics. Possibly something useful will come of it - we'd all be the better for that.

 

 

[Bruce Tuncks]

My indicated temps in normal operation don't go above 160 C. I reckon that keeping the engine cool really helps. I've got bigger inlet holes in the top cowl and extra baffling to maximise the cooling air past the fins including the so-called "gull winged" bits on the underside of the cylinders.

 

Also the oil-cooler hole is partially blocked off to help keep the lower-cowl pressures down . I was prepared to add a lower-cowl skirt but this has proven to be not needed.

 

Well (touch wood) it has run just fine for 13 years now but only 450 hours.

 

It's not good to argue from individual cases, but I only know of 2 guys who gave up flying after engine scares. One was a Rotax and one was an aero-volkswagen type.

 

 

[motzartmerv]

Bruce, heat certainly does seem to be the issue. Unfortunately we can't modify the factory built training aeroplanes.

 

 

[Oscar]

Bruce- your engine is very likely to run full TBO on those figures. You've evidently approached the issues calmly and intelligently and you're getting the rewards. Nice to hear about good results coming from intelligent tweaking and careful development of a decent engine operating environment. Your posts elsewhere re LiFEPo4 battery use has been damn good information and I'm enthusiastic about that possibility. This is the sort of stuff that makes visiting this site worthwhile.

 

 

[SDQDI]

Merv, you're more than welcome. I 'll do what I can to add value to any discussion of Jabirus.Now, let me point out that an 'anomaly' by its very definition does not add to the evidence for or against a general thesis so the thesis stands until proven nonviable by actual statistical evidence. Anomalies are not statistical evidence.

 

Am I getting too academic here? - I apologise if I am, but nobody told me I had to leave my intelligence at the door to be a real aviator in the RAA scene. I have to admit that that suggestion has come as somewhat of a surprise to me, as plenty of the RAA people I know don't seem to have any such problems with people using intelligence or even polysyllabic vocabulary. I'll certainly try to leave my education behind if I venture north of the Qld north-south divide, even though I know people in Townsville who can count to ten without using their fingers, and who enjoy things such as Chamber Music festivals and philosophic conversation. If I need to, I'll take up chewing tobacco, spitting and using single-syllable words (or should I call it not using posh language?) if I venture back there. That's going to be a bit hard, even 'Mate' has more than one syllable, but in the interests of good communication, I'll try. My last memory of Townsville is being regarded suspiciously by a barman for trying to buy a bottle of red after 6.00 p.m. on a Saturday evening; I ended up being written about in the local newspaper for having intimidated the same barman.

 

However, having looked at the stats so far produced, it seems to me that somewhere around 34 Jab. owners have responded. That seems to suggest that somewhere more than 1,000 Jab owners are not sufficiently concerned about their engine life to contribute to this forum. My appreciation from contributing to this site is is that something like 20 or so forum members are vehemently opposed to Jabirus, and I frankly think I can be of more use providing what information I can to the other 1,000 plus than fighting with what may well be described as the 'rump' of Jabiru commentators. (see: http://www.oxforddictionaries.com/definition/english/rump , definition 2).

 

So, good luck with your campaign to gather statistics. Possibly something useful will come of it - we'd all be the better for that.

You do know Oscar that you don't have to speak smart to be smart and using big words in no way proves you (or whoever is using big words) are smart. actually most (not all but a majority) people using big words are quiet average in their smarts:yes:

I think it would be nice if we could argue in simple English ( then I will understand what you are all saying to each other)

 

 

[Guest ozzie]

About time some serious petitioning be directed towards the RAAus and CASA to implement these modifications to the 24: aircraft that are obviously working and improving the reliability of these engines.