motzartmerv

Thats ok Gandalph, we are back to using car analogies now. There is a diff between advancing a design, and bandaid engineering. How many AD's and SB's for through bolts are there? Decompressed (shimmed heads) etc.All marketed as 'improvements . Then a few months later, nah, through bolts need upping again, take out the shimms. This is not Advancing a design, its patching up problems. If we are using car analogies again, who has ever replaced an old engine with a brand new one in an old car when the car was operating normally?

Just a quick one nev. When you search the jab sales website does it say " evolving design" in th engine specs? If you buy soenthing you should expect it to work as is.

Ok so now we can compare to automotive engines? Jet you know very well I'm not against a safer design, you have missed my point entirely. I don't know how else to say it, and I can't keep up with the rules about exactly what comparisons can be made. So I'll just go mow the lawn with my old brigs n stratin that hasn't required any major ( or minor ) mods in decades.

And here, we arrive at the point. If it aint broke, why would there be a new improved version at all? The new version becomes the norm and if you didnt get it, its YOUR fault the engine is shagged?

Im afraid im not on this page with you at all Nev. I find myself flying into unfamiliar territory here, and that is, dissagreeance with you. I am sold an aeroplane. I Pay for a new Item, i should have the reasonable expectation that that product a) Should fit the purpose AS IS, as for which it was sold b) Should the engine require a significant mod ie, new heads, then this should not be at my expense. I have paid for the engine once. Why should I be buying ' upgrades' AT ALL? While i appreciate that aero engines are not mass produced car engines, consumer law still applies. And if I am told that the aircraft i bought, when operated IAW with the 'instructions", should last me XXX amount of hours AS IS.. Then I should expect it to do so. If Jab release a 'better design' later on, then jab can express post me the new parts with a blank cheque to pay my engineer to fit it. Possibly far too simple a view, but Im certainly not onboard with this " rolling buiold ' idea that seems to be so accepted by the factory as a way of operating. I call it bandaid or 'reactive' engineering, instead of pro active. Fly cut pistons ? Really? Instead of fixing the problems that CAUSE valve impacts on pistons crowns , we cut grooves in the cylinders for 'room' so the valves dont impact any more. So when my valves start bashing in, I call the factory and they say..Oh, you dont have the new flycut pistions.. Its now MY FAULT the engine is playing up. Can you see why as an owner, I would not be very interested in hearing how theres new better ways of doing things after Ive bought and paid for my engine?

Depends Russ, as long as you keep paying for the upgrades and the latests versions, no worries. she will get there:)

Im confused..Is it a sportstar or a Piper sports?

Probably true. And I agree with Jabiru in one respect, if they didnt suffer these recurring issues and failure modes, the 'normal" failure modes would be reasonably low. Lets face it, its either Thru bolts, or valve trains . Sort those problems and i wouldn't imagine many failures at all. In fact im scratching to think of a failure Ive heard of that wasnt related to either of these.

Yes, and this is my point. Any pilot will see elevating CHT's etc and increase climb speed or decrease power or both. My point is, WHEN? At what point do we take this action? Some will say its a normal part of flying and yes, of course it is. But, if we are using instrumentation and "NUMBERS" given us by the factory, then we can climb the aeroplane as hard as we like, until it reaches these pre defined 'limits' and then back off yea? Not advisable, but still operating " within limits". And here is the problem. I dont think the true limit is 180 deg's and 200 max. I dont believe this is correct. I dont think these engines can be operated within design specs IAW with jabs documents. That is my point. Any pilot should know about managing heat on a climb, BUT, he or she is only as good as the info he's basing this management plan on. If the POH states max continuous CHT is 180, then he can drive it all day at that temp and be operating IAW Jabs figures. THESE FIGURES ARE WRONG IMHO

Not sure what your getting at there Nev? Too much airflow on approach when doing a normal approach 6 or 7 times an hour, over hundreds of hours, not alot I can do about the extra airflow, all we can do is operate it inside the specs in the POH, ie, appch speeds etc. Again, this is sold as a a training aeroplane, if I cant do a normal cct in it for fear of the heads shrinking then I would argue its uselfull ness as a trainer . We do ccts in all types, I think you have missed my point entirely. My question is " What is so different about a Jab, that it cant handle the treatment for which it was supposedly designed?" Should I limit circuit operations in jabiru powered acft? Should I modify how we fly an approach? Fly out 5 miles and do attitude approaches on the power all the way in with a flat profile to keep heat in the heads? Thermo nuclear means it had a runaway in CHT on one pot. Went to 230 deg's in a matter of seconds. The factory could not provide an explanation for this, nor could an independent assesment.

I posed this question because I have a genuine interest in it and its ramifications, particularly for an engine marketed and sold as " a training platform". Everybody that replied is correct . Things like: * Adequate warm up time * Engine monitoring (with non standard instruments) * Increased climb speed to increase cooling * Correct mixture ( Automatic, not manual) My point is, NONE of this is new. None of those techniques are anything a pilot shouldn't do with ANY aeroplane engine. Students have been flying manual mixture control engines since the 50's,in numbers that make Jabs totals pretty negligable. and im not aware of a significant recurring failure mode in the major engine types relating to the same problems we are having here. A well trained student will NOT take off until T's and P's are green (IAW POH) A well trained student will monitor climb temps and climb with an increased airspeed to improve cooling Any half trained mechanic can spot a lean or rich mixture during maintenance on ANY engine. What makes this engine any different? If the engine requires full CHT EGT monitoring then that instrument should be standard equipment. If the engine cant be climbed IAW with the POH, ie, VY at max continuous (FULL POWER) CHT not exceeding 180 deg's for more than 5 mins,then change the bloody thing. On a 230 that went thermo nuclear on one cylinder, we had 6 channel monitoring on CHT and EGT. Right up until the moment it went mental, it had NO over temp indications (IAW Jabs specs). ie, it never went more then 180 deg's for more than 5 minutes (IAW POH) It never exceeded 200 deg's c (IAW with poh) and yet, turning xwind the thing went nuclear. I have two contentions, after suffering every common Jabiru engine failure. 1. The engine can NOT tolerate operating at 180 deg's (CHT) as stated in the POH 2. During normal circuit operations, the heads cool too quickly. Im no engineer. Im no mechanic, but I reckon those two things are playing a huge part in this saga. I have no DATA to suport my notions, other than the facts gathered by operating many Jabs, in many locations and NONE of them making TBO. Some L2 maintained, some LAME maintained. Most run on 98 octane mogas, some run on Avgas.

The stats have een posted in this thread. Look back a few pages.

Thanx Bruce. My engineer is doing a jab course as we speak. Hopefully they will juice him up. As a school, we can ONLY maintain IAW the published jab procedures, so I'm interested to know how any tweaks can be done an still be IAW te manuals.

How can a pilot " handle " the jab engine in a way to minimize through bolt failure? Genuine question.

Yea the stats are out.

if that were true, how the hell is Tony Abbot still PM?

Mmmm.. Fixed the problem?

Jut recieved another email from the jab factory. I really think they need to stop trying to convince the world of their goodness and start adressig the issues. In the email they stated the new through bolts have sorted the issue. But I would disagree. They also state that only flying schools seem to have failures. Again, I don't agree with this, but not a good look for an aeroplane sold as " the worlds most affordable training plane" If I was jab I would stop the emails and start fixing!!!

I can only answer that from what I've seen , yes- this latest failure was a post mod.

No, was crap typo ( auto correct) sorry mate.

Sorry for the typo chird. I meant to say I have had 3 thru bolt failures. So 10% of the reported cases. One was explained, one was out of the blue on a high hour engine, the third just recently at 300 hrs post top end overhaul. My suspicion is it's related to the flywheel failure 80 hours ago.

Typical govt speak tho, after laying the boot into jab last week, they cover their butts with: No conclusive determination has been made by CASA about the integrity of Jabiru engines, and no determinative findings have been made by CASA about Jabiru’s ability and willingness to produce safe, sound and reliable aircraft engines.

Interesting, and the first time we have heard from CASA since this all started. i dont read much back peddling at all, just perhaps a bit of calming people down. Ill just add the bit you left out bush pilot :) CASA is proposing this action as a precautionary measure, pending identification and rectification of the causes of what appears to be an extraordinary high rate of partial and complete Jabiru engine failures.

No, im not saying that. I dont doubt jab have that many reports. Im suss that theres many more un reported.

Yea im suss on those numbers. I know of a dozen myself, surely i cant know almost 1/3 the worlds population of through bolt victims?