Jabiru Bad experience
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Jabba,
"Complete lack of data along with so many experts having their opinion along the ay mean finding the truth is almost impossible"
This is why I want them back, and that's why they won't give them back!
"Complete lack of data along with so many experts having their opinion along the ay mean finding the truth is almost impossible"
This is why I want them back, and that's why they won't give them back!
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Ok thanks. I thought Deadstick gave a pretty detailed explanation about both failures, with an engine report aswel. I was just relaying what happened from the cockpit. Not being an engineer I am relying on the lames technical description of the post failure inspections.
Your right about the experts. But even the factory experts (small engine mechanics) have not been able to explain why either of these failures occurred.
Your right about the experts. But even the factory experts (small engine mechanics) have not been able to explain why either of these failures occurred.
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It would seem DeadStick that based on the information from your previous post that your warranty is void unless there is a subsequent SB after JSL007-4 from December 6th 2011.
http://www.jabiru.net.au/Service%20B...l_Guidance.pdf
(Not my boldings)
3.3 Shandies
A "shandy" is a mix - for the purposes of this letter it is a mix of any 2 or more different fuels.
In some areas it has become popular to operate Jabiru engines on a shandy of AVGAS and MOGAS. This might be done to reduce the cost of fuel, to reduce lead buildup in the combustion chamber, to "beef up" the octane rating of a sub-standard fuel or other reasons.
This practice is unsafe. Jabiru Aircraft do not endorse it and may void any warranty of an engine or aircraft which has been operated using such a fuel.
In terms of chemical composition AVGAS is totally different to MOGAS. A petroleum company representative described mixing the two as similar to "mixing Gin with Beer".
Hardcore cocktail fans aside, mixing these drinks is a bad idea – it tastes bad and the after affects can be messy & expensive. There is potential for elements in the fuels to react to each other and the finished blend would have unknown knock resistance – because the fuels are so complex you cannot assume that mixing 110 RON AVGAS with 91 RON MOGAS – at almost any mixing proportion – will result in a fuel with acceptable knock resistance for a Jabiru aero engine.
http://www.jabiru.net.au/Service%20B...l_Guidance.pdf
DeadStick1 Fuel used primarily is Caltex 98, but when away, fuelling at other strips they use avgas.
3.3 Shandies
A "shandy" is a mix - for the purposes of this letter it is a mix of any 2 or more different fuels.
In some areas it has become popular to operate Jabiru engines on a shandy of AVGAS and MOGAS. This might be done to reduce the cost of fuel, to reduce lead buildup in the combustion chamber, to "beef up" the octane rating of a sub-standard fuel or other reasons.
This practice is unsafe. Jabiru Aircraft do not endorse it and may void any warranty of an engine or aircraft which has been operated using such a fuel.
In terms of chemical composition AVGAS is totally different to MOGAS. A petroleum company representative described mixing the two as similar to "mixing Gin with Beer".
Hardcore cocktail fans aside, mixing these drinks is a bad idea – it tastes bad and the after affects can be messy & expensive. There is potential for elements in the fuels to react to each other and the finished blend would have unknown knock resistance – because the fuels are so complex you cannot assume that mixing 110 RON AVGAS with 91 RON MOGAS – at almost any mixing proportion – will result in a fuel with acceptable knock resistance for a Jabiru aero engine.
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At what stage did I say I was using a "shandie"? lol
I have asked the factory about this on a previous occasion, they stated that its fine to top up on either fuel provided one or the other is the majority in the tank. Also I was told that it was to stop a trend that was developing, of people mixing 91ulp with avgas! had nothing to do with 98+.
When I say fuel up at other locations its a case of leaving 'home base' burning down to practical and topping up with the other until I get home.
To be clear the engine is out of warranty!
I have asked the factory about this on a previous occasion, they stated that its fine to top up on either fuel provided one or the other is the majority in the tank. Also I was told that it was to stop a trend that was developing, of people mixing 91ulp with avgas! had nothing to do with 98+.
When I say fuel up at other locations its a case of leaving 'home base' burning down to practical and topping up with the other until I get home.
To be clear the engine is out of warranty!
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XXX the longer this goes on the more you sound like a factory rep. The guy has come on here to air his grievances about what appears to me to be a legitimate issue...not just for him but potentially all Jab drivers. It would seem that every scenario you have suggested has been adequately explained, now it just looks like you are the one pooh-poohing....just like Jab seem to be doing!
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Hi all, long time watcher here.
I owned a Jabiru UL450, purchased it from the builder here in NZ.
Total engine hours are about 850, and has run perfect since day one. This is a 2200
Only issue I have had, is that uncommanded flap retraction, which was on very short finals, as soon as it happened, I applied full power and didn't hesitate to go around to check what was up and happening.
What caused that? Simple, just wear on the through bolt, quick tighten and check, and never happened again.
I owned a Jabiru UL450, purchased it from the builder here in NZ.
Total engine hours are about 850, and has run perfect since day one. This is a 2200
Only issue I have had, is that uncommanded flap retraction, which was on very short finals, as soon as it happened, I applied full power and didn't hesitate to go around to check what was up and happening.
What caused that? Simple, just wear on the through bolt, quick tighten and check, and never happened again.
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Deadstick
Just to clarify then.
1. Caltex 98 is fine, but it will increase CHT over Avgas (100MON or about 110RON) The shandi mix of 98/avgas is fine and I agree with the blocking 91UL/avgas.
2. The piston ring sticking with avgas is a known issue, should have been helped with the latter piston design with wider grooves not the std groove of a ULP auto engine. I have no idea how successful this was or is.
3. Seems CHT is a major contributor and I wonder just how well the cooling works around the whole area of the cylinder.
My opinions.....OK...these are WAG's but from a semi reasonable position to comment. Oil changes every 25 hours and not 50. Keep the indicated CHT (not necessarily the entire head) below 300 as there may well be parts that are much higher. Head torque checked every 25.
Climb speeds need to be nothing like the range of Vx or Vy and my suggestion is take Vy and x 1.32. Good reason for this, but not related to the topic but it will give you the climb sped I feel is likely to yield better results.
Email address is on its way. Probably not much more I can add here.
How does a run away CHT relate to the bottom end being destroyed? Unless the rer was a destroyed piston and the debris went through the places wrecking everything else. Or magically the heat was channelled through one pot? 
Does not add up does it?
Just to clarify then.
1. Caltex 98 is fine, but it will increase CHT over Avgas (100MON or about 110RON) The shandi mix of 98/avgas is fine and I agree with the blocking 91UL/avgas.
2. The piston ring sticking with avgas is a known issue, should have been helped with the latter piston design with wider grooves not the std groove of a ULP auto engine. I have no idea how successful this was or is.
3. Seems CHT is a major contributor and I wonder just how well the cooling works around the whole area of the cylinder.
My opinions.....OK...these are WAG's but from a semi reasonable position to comment. Oil changes every 25 hours and not 50. Keep the indicated CHT (not necessarily the entire head) below 300 as there may well be parts that are much higher. Head torque checked every 25.
Climb speeds need to be nothing like the range of Vx or Vy and my suggestion is take Vy and x 1.32. Good reason for this, but not related to the topic but it will give you the climb sped I feel is likely to yield better results.
Email address is on its way. Probably not much more I can add here.
Recap gents,
the 230 suffered a cylinder head overheat on number 4 only no valve seat movement or valve failure, the subsequent bulk strip at the factory, revealed the bottom end was destroyed by the original inadequate thru bolt design.
the 230 suffered a cylinder head overheat on number 4 only no valve seat movement or valve failure, the subsequent bulk strip at the factory, revealed the bottom end was destroyed by the original inadequate thru bolt design.
Does not add up does it?
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Jaba,
Surely in this age of technical expertise they can design a better engine than this?
I only ever flew Jabirus and other Ultralights for a very limited number of hours and could never feel at ease with the engine spinning above 5000 RPM. I realise they need this speed to produce the desired power output, and it's a case of chasing ones own tail regarding power vs weight.
Spend enough money and anything is possible.
Sorry for the link, couldn't get the Youtube link thingy to work?
https://www.youtube.com/watch?v=nsa6kq-qqIE
This video shows an operational cutaway of a BMW S1000RR — a 193HP superbike — bumping against its 14,200RPM redline. A cam and valvetrain at 118 cycles per second is an amazing sight (and sound)
Obviously not a suitable engine for an aircraft and probably has HUGE maintenance / reliability problems of it's own. However a pretty cool video to watch.
Oil changes every 25 hours and not 50...
Head torque checked every 25...
Head torque checked every 25...
I only ever flew Jabirus and other Ultralights for a very limited number of hours and could never feel at ease with the engine spinning above 5000 RPM. I realise they need this speed to produce the desired power output, and it's a case of chasing ones own tail regarding power vs weight.
Spend enough money and anything is possible.
Sorry for the link, couldn't get the Youtube link thingy to work?
https://www.youtube.com/watch?v=nsa6kq-qqIE
This video shows an operational cutaway of a BMW S1000RR — a 193HP superbike — bumping against its 14,200RPM redline. A cam and valvetrain at 118 cycles per second is an amazing sight (and sound)
Obviously not a suitable engine for an aircraft and probably has HUGE maintenance / reliability problems of it's own. However a pretty cool video to watch.
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XXX the longer this goes on the more you sound like a factory rep. The guy has come on here to air his grievances about what appears to me to be a legitimate issue...not just for him but potentially all Jab drivers. It would seem that every scenario you have suggested has been adequately explained, now it just looks like you are the one pooh-poohing....just like Jab seem to be doing!
Those that haven't yet seen this might find it interesting:
New Camit Aero Engines | CamitAeroEngines
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2 dogs. i dont think you flew a jab that revved at 5000 rpm. A rotax powered jab perhaps?
I agree though. We should have better engines avialable. I recall jabiru brought out a recommendation that the engines get a 25 hourly oil change. We immediately adopted this procedure IAW with factory directions. The 2200 engine was subject to this schedule at the time of the failure, and (at a guess) for the previous 100 hours leading up to it.
I agree though. We should have better engines avialable. I recall jabiru brought out a recommendation that the engines get a 25 hourly oil change. We immediately adopted this procedure IAW with factory directions. The 2200 engine was subject to this schedule at the time of the failure, and (at a guess) for the previous 100 hours leading up to it.
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motzartmerv,
I do believe they were Rotax powered. Long time ago now.
I just remember the poor little things screaming and wondering how reliable they were. I saw the internals of a few and decided they looked a bit ...
There were some issues with the engines and the flying school eventually went Cessna.
I do believe they were Rotax powered. Long time ago now.
I just remember the poor little things screaming and wondering how reliable they were. I saw the internals of a few and decided they looked a bit ...
There were some issues with the engines and the flying school eventually went Cessna.
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Rotax reliability is now on par with the big bore cousins,Lycoming and continentals. i am just as confident behind a rotax as i am behind the IO540, even fly my own at cruise rpm of 5200rpm, keeping the revs higher keeps the internal pressures lower, runs smoother and never had a fault yet in just on 1000hrs behind it. i will fly behind jabs, and have flown them for quite some time, but i find myself a little more vigilant of potential landing areas when behind the jabiru.
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Jabba
It could be related as follows. From time to time when using nearly 100% unleaded (especially during long hot slow climbs) the peak pressure moved back to TDC thus exerting a greater than normal load on the bottom end and high heat loads on the top end. The engine was strong enough to cop this a few times but couldn't do it forever.A bit like a mistimed engine--sometimes you get away with it but for how long?
Eventually with maybe a bit of help from detonation the engine throws in the towel.The first cylinder to overheat detonated and the bottom end weakened with the through bolt issue and earlier unwitting abuse, fails.
This is not necessarily what happened but it is a possibility. I wonder how many failures of this type of have occured in engines which never use mogas.
Cheers RA
How does a run away CHT relate to the bottom end being destroyed?
Eventually with maybe a bit of help from detonation the engine throws in the towel.The first cylinder to overheat detonated and the bottom end weakened with the through bolt issue and earlier unwitting abuse, fails.
This is not necessarily what happened but it is a possibility. I wonder how many failures of this type of have occured in engines which never use mogas.
Cheers RA
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This is not necessarily what happened but it is a possibility. I wonder how many failures of this type of have occurred in engines which never use mogas.
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The independent engine inspection report details that the bottom-end damage wasn't a result of the engine over-heating.
Perhaps DeadStick you can post that report on here too please for the likes of Jabba and others?
Perhaps DeadStick you can post that report on here too please for the likes of Jabba and others?
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if it was fuel/mogas related, then wouldn't we see the similar failures within the rotax fleet,
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More importantly, the annomoly would show up in the num,bers. There is no evidence to suport EITHER fuel being more or less "unreliable" in jab engines that im aware of. If 98 octane was causing issues, then im sure we would be onto it by now., The fact is there seems to be no common denominator. We have looked, hard. The only real thing we have noticed, is that blokes who do NOT follow the advice from Jab seem to have a better time. I dont mean that in a nasty way, its an observation.
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Two dogs,
Do not confuse me with the factory, but my comments were just an opinion in this case, and stated as such, that with a very small sump Qty, leaded fuel and high f/a ratios that more often would be prudent. In fact Rotax recommend this is using leaded fuel. As for head torque, sure they could design a better method, like a TCM/LYC design, but it is not.
RA....that is a long bow to draw as you say, but yeah I can see it is possible. I doubt the C98 or BP98 would be enough of a change in thetaPP and the timing is fixed, but what else? Again how would we know. Not enough data or evidence so far.
UL
the Rotax engine is a water-cooled head and a bit different to an air cooled TCM/LYC etc in that respect. It has a similar compression ratio or a bit higher and 26DBTDC, so it is taking advantage of the H2O and 98PULP
Do not confuse me with the factory, but my comments were just an opinion in this case, and stated as such, that with a very small sump Qty, leaded fuel and high f/a ratios that more often would be prudent. In fact Rotax recommend this is using leaded fuel. As for head torque, sure they could design a better method, like a TCM/LYC design, but it is not.
RA....that is a long bow to draw as you say, but yeah I can see it is possible. I doubt the C98 or BP98 would be enough of a change in thetaPP and the timing is fixed, but what else? Again how would we know. Not enough data or evidence so far.
UL
the Rotax engine is a water-cooled head and a bit different to an air cooled TCM/LYC etc in that respect. It has a similar compression ratio or a bit higher and 26DBTDC, so it is taking advantage of the H2O and 98PULP