Oscar

Solid lifters, conventional lifter. And, they sell a conversion kit to change a hydraulic lifter engine back to solids.

 

 

Every new Jab (and CAMit) engine that comes out of the CAMit factory is dyno- run for at least 20 minutes, with clear covers installed to check that the oil feed to the rocker area is working properly. They're natty gadgets, and would probably be useful for any re-builder to have for that purpose.

 

 

A lot of stuff goes un reported, there are several reasons for this, and to be honest the RAA in general doesnt have a ' reporting culture'.I know its the rule etc, but dont put a lot of weight in this, I know many many operators that just dont bother.

If you report everything that goes wrong, then you can expect a please explain from the RAA as to why your having so many issues.

 

So your dammed if you do, dammed if you dont. Dont flame me over this, I report everything, and I also have been asked to explain the ' rash' of reports..

 

Its not very conducive of encouraging a reporting culture, and It interesting to see how it gets handled. I have posed the question to the RAA, 'are you asking the manufacturer to explain this rash aswel', or is it just me? Reckon I get a reasonable response? .......

Merv, this is - and I am not questioning the accuracy of your statement that I bolded in the quote above - surely a serious matter?

 

Australians tend to think of 'dobbing in a mate' as a socially unpleasant action. I certainly share this attitude in general and I am sure that if I think about it there are numerous examples in my life where I have not reported something that perhaps should have been reported in the context of the possible consequences that perhaps didn't materialise due more to good luck than good management or intentions.

 

However, we have had on this site, more than a few discussions about the importance of drawing attention to unsafe flying habits and I believe that just about all of us here agree that it is in the best interests of both the individual and the organisation that patently unsafe flying behaviour be reported.

 

Is there any qualitative difference between reporting unsafe flying habits and reporting unsafe maintenance or incidents? The end result of either could quite possibly be death or serious injury.

 

Something that is a safety problem, or has caused an incident that is in the ambit of 'reportable' under 4.08 of the Ops. manual, might not in that particular case have resulted in anything serious BUT knowledge of it might well prevent a later occurrence that had a far worse outcome. From your comments, you recognise this and duly report, and that - surely - helps improve safety for all.

 

There is a time-honoured adage: 'if we don't learn the lessons of history, we are doomed to repeat it'. Pretty obviously, if the 'lessons' are not reported then how can people 'learn'?

 

 

Thanks to Turbs' effort (and mighty collection of the RAA mags.), this has to be one of the most useful advances in getting perspective on the whole story that we've had.

 

It does seem somewhat glaringly obvious that the depth of recording (and probably, I guess, reporting) of the circumstances of the failures has not provided much more than a simple 'this is what happened'. Again, I believe that Don Ramsay's call for better performance in both of these areas is likely to considerably advance the understanding of the situation, and even the development of a relatively brief pro-forma type of reporting that covers a wider range of information would help.

 

Preferably, this would be accomplished by on-line reporting in a format that would feed a database so that analysis can be quickly carried out, with I guess a paper back-up for those unable to access the on-line system. There'd need to be some explanatory material for entering the details so that common terminology is used, and also that we don't get the legendary 'electrical failure' [because the broken rod pushed the plug leads off]' type of entry..

 

While I suggest it is probably correct that some failures do go unreported (and certainly, there is anecdotal evidence for this), I'm not sure how much weight can be placed on that to suggest there is any vast pool of unreported failures. As far as I am aware, it is a requirement to report these and I wonder how many people fail to meet that requirement; there doesn't seem to me to be any advantage to not reporting such failures when it is a requirement. That some aircraft have been pushed into the back of the hangar/shed because the owner is concerned about the engine and 'will get around to it' someday I'd suspect IS certainly a factor in reducing potential failures - but we don't have data to either support or deny any of this. One could equally suggest that there are plenty of owner/operators who are unconcernedly flying along out there with Jab. engines who don't have anything untowards TO report - though perhaps 'unconcernedly' is not the right word, and I'd accept 'with due concern' (for their maintenance, operation etc.) as being more likely. However, as with other assumptions, this remains just that - an assumption.

 

The work done so far is a pretty quantum leap in improving the understanding of the whole Jabiru 'engine failure' raw numbers; a better reporting system that would indicate at least even general areas of 'cause' would be the next useful step.

 

 

Is your average service life the service life of those with a failure or the service life of all engines of that class - which would include those that haven't yet failed - all part of MTBF. Of those which have not yet failed , what life can one expect.The really important failure rate is failures per hour run NOT failure rate per aircraft (whether on the register or not)

I don't believe we have any figures for the service life of all Jab. engines, just those that have been the subject of failure. There are something like 2,000 Jabs. in current service in Aus, these figures tabulate the history of 35. I would not suggest that there are not a considerable number that have been 'retired' early in their expected life as a result of inspection in maintenance, but I think it is a rather small statistical survey from which to try to draw definitive conclusions.

 

 

I wont, hes busy running through oscars log books and stuff ay?

Ah, I wish it were so, in terms of getting my aircraft back in the air.

 

But in reality, Darren has much on his plate, including trying to get a better system of assessing risk for amateur-built aircraft systems so we don't - hopefully - have the losses of life that happened at Moruya repeated. That is way more important than the progress on my aircraft, if perhaps we can leave snide comments aside for a moment. Also, I have the opportunity of contributing in some small ways to the improvement of Jabiru engine reliability, which has obvious implications for my own Jabiru. To me, that seems a worthwhile distraction.

 

 

This is a batch of 35:The typical report goes like this one:

 

Jabiru LSA 55, Engine: Jabiru 2200,358 hrs ttis.

 

The aircraft had completed several circuits and was at a height of approximately 150 feet when two loud bangs were heard and the engine failed.

 

A forced landing was carried out in a ploughed paddock where the aircraft flipped over and came to rest inverted. The pilot and passenger suffered abrasions and cuts requiring sutures

 

Inspection of the engine revealed that a cylinder had separated from the crankcase.

 

Probably not enough for you, but enough to categorise the failure.

 

Just for the moment disregard totals for the timeframe because it only represents about half the reports. I now have the balance and have dragged the magazines out on to my desk.

Turbs - do you have that table in a spreadsheet? This is seriously useful stuff and some statistical analysis would likely be very instructive. It would need more background information on the circumstances of failures to really pinpoint causes rather than just results, but it's a hell of a good start, and RAA - and Jabiru engine owners - owe you one for the work that you've put in.

 

Your 'typical example' is remarkably close to an entry in the logbooks for my aircraft. From having dismantled and rebuilt the engine from the last failure - that ended in a tip-over (as described almost perfectly what happened) it is evident that a forensic examination of that aircraft's history shows that it has a pattern of engine failures that need to be considered in terms of the operational parameters under which it was used, that that particular engine (a zero-timed rebuild) should never have been returned to service, and that by examination, the maintenance work undertaken on the aircraft was seriously deficient in quality if not quantity.

 

We need to get beyond the philosophical conundrum of the assertion that 'All elephants are grey, this animal is grey, therefore it is an elephant'. We need to look at the difference in all the factors between a Jab engine that fails at, let's say, 358 hours and one that runs to 900 without any problems at all. Your research shows that there are examples of 900+ hours TTIS (indeed, up to 1900 hours!), and examples of 155 hours TTIS. A fundamental design problem does not produce differentials of that sort of magnitude.

 

If we can get the sort of detailed information that would allow us to even put boxes around failures so we could identify 'at risk' vs 'safe' operational parameters, that would be a major improvement in the knowledge base.

 

 

Well, that IS good news. The more the merrier here, I suggest. You might, however, find it useful to learn the difference between a valve guide and a valve stem, before embarking on any wholesale and expensive development project.

 

 

Merv, your own experience recounted above is exactly the sort of information that is needed to develop a comprehensive picture of the problems, and from that, the potential solutions. You commented that, the 'best' Jab. engine experience you have had was with the one that ran the coolest, and the whole issue of heat - and specifically, heat that goes out-of-conditions that the engines have been tested to JAR22H to meet - has been been something that many have commented upon as critically important to Jab. engine life.

 

Why engines go into out-of-condition heat ranges is obviously something that needs in-depth examination, which is why I emphatically support Don Ramsay's call for far more in-depth investigation and documentation. It can be for a number of reasons including use, petrol quality, inadequate CHT and egt reporting, cooling set-up. If all the information could be collated, sifted through, common factors identified, ranked in importance and solutions tried and proven, every Jab engine user would be way ahead of where we are right now.

 

 

Thanks, PM - I was on my first cup of morning coffee and the cold start kit is struggling in the temps. down here...

 

 

Try punctuating the following. It can be done, in perfectly good English:John where hadad had had had had had had had had had had had a better response from the English teacher.

John, where hadad had had 'had', had had 'had had'; 'had had' had had a better response from the English teacher.

 

 

...and a major player in the world market. Rotax may sell ten times the number of engines, but the new boy (D-Motor) chose to make their engine compatible with a Jabiru mount.

And the UL Power UL260, also has identical mounts with the J2200.

 

 

If you are writing a sign, you might want to consider this: 'Would my 'Fish-And-Chips' sign have been clearer if quotation marks had been placed before 'Fish', and between Fish and 'And', and 'And' and 'Chips' and also after 'Chips'?'

 

 

And the Rotax 912 series, other than the A, F, S and iSc are ( as of recently, at least) uncertificated. The 912 F is certificated to FAR 33. The 912 ULS is, as far as I am aware, still uncertificated.

 

 

Jeez, give the salesman some slack! If anybody has ever better demonstrated: 'and by the way, DON'T do this' to a potential customer, then he/she deserves a Gold Elephant Star and a beer in the pub afterwards.

 

 

Hey, why don't you just DO that? There's over 5,000 Jab engines been produced, that's 20,000+ heads! Got to be a great market. I believe Rotec have sold 83 sets of heads already.

 

The Jab engine owner world awaits you!

 

 

Wow, And I'm sure Darren is looking forward to the condescension I mean meeting! LOL. Special meetings with the Tech manager to go through your photos, videos and repair logs! Your faint grip on reality is as you put it in a previous post, laughable or hilarious!I'm not sure why you would want to waste the tech managers time to go through your logs, etc unless its for some self gratification or confirmation that your repairs are legit! If its the latter I thought you were the 'bomb digity' when it comes to aircraft! Especially Jabiru's....

Not much Darren could tell you that you don't already know, right?

 

Cant wait to see this jabiru of yours in the flesh! must be special!!!

 

sigh...

Ah, Darren will already have had the EO and the L2 and L4 tick-offs. And the structural proof-tests reports, and the flight tests under VH-exp category. And he might just wish to review the performance of certain L2's, he seems to be a decently meticulous person by nature. Or perhaps that is not something that you'd wish to see happen in the RAA?

 

 

The Pilot would hardly have had time to get depressed at the loss of his aircraft, retrieve the pieces and start to pull the engine down, but his description of 9 years of reliability then the engine starting to run rough, matches a number of other stories which ended with through bolt failure - my pure conjecture.For those who have drifted into the discussion on cooling, failed exhaust valves etc. I posted this thought piece on another forum this morning. I had similar combustion issues with a race engine for a couple of years, and solved the problem after understanding where the heat was and how to get rid of it.

 

Get an old exhaust valve, heat it gently with an oxy torch until the temperature is 200 degrees C measured with a probe thermometer. It should look much the same as when it was cold.

 

 

 

 

 

In a water-cooled engine this temperatures are significant because sensor usually are tapped through the head to measure the water temperature, and as we know the boiling temperature increases with the pressure we can obtain in the cooling system. If we lose pressure the head temperature goes up and the head usually warps.

 

However the exhaust flow is deeper and directly in the flame front of the combustion chamber, where operating temperature is around 1,000 to 2500 degrees C – a different environment.

 

Get the oxy torch on the old valve again and take the temperature up again – steel usually starts to get soft around 538 degrees and melts around 1370 to 1540 degrees C, so in this experiment you’ll be able to roughly find where the material for this valve would start to burn away.

 

If the valve is deforming at the low end of the scale, you can look at better valves, if not, then the flame front may not be clearing fast enough from the chamber to allow cooling before the valve starts deforming and shedding.

 

You could use the percentage difference say between 180 and 200 on the gauge, but it’s not terribly representative of what the flame front is doing.

As anybody with a basic understanding of four-stroke engine thermodynamics knows, there is bugger-all heat transfer through port flow in the exhaust port. The valve stem carries some of it, the valve guide and the seat carry the rest. The head and the cylinder ultimately dissipate the heat to the cooling medium (water, oil or air). Titanium valves, sodium-filled valve stems, beryllium-alloy valve seats and various types of valve guide materials have all been used to improve the heat transfer / heat tolerance regime, with titanium valves being also useful for valve-train inertia reduction . No race engine engineer I have ever met/worked with has considered port flow from the POV of heat transfer from the valve/ seat/guide - though as you say, flame front/ velocity erosion is a matter of concern. Our wee mate Bex appears to be suffering from a spatial dislocation of his mouth to about two feet south of its conventional location. Not a good look in a supposed engine designer.

 

 

This is rather worrying Oscar, I trust you have filed a report with RAAus?

A condition report (about six pages, with photos) when transferring the rego and a defect report, yes. However, we intend to meet with Darren Barnfield and go through the logbooks and our hundreds of photos and probably more than a half-an-hour of videos of repair work. Our interest is getting the thing ticked-off as OK to fly again as a 55-rego aircraft; where RAA may want to go with our documentation, is their concern.

 

 

I borrowed a set of heads from a forum member recently and had them flow bench tested in the hope that the exhaust port may be able to be reflowed to aid cooling but alas not enough mods within the current casting would be able to be made to make any major differences.I haven't had time to continue with that pursuit at this moment but still hope to get a standard head and one modified to a porcupine finned head to see if that is effective.

Port flow affecting cooling? You are so far off understanding the physics of heat transfer that it is bloody laughable.

 

Sorry, edit - delete 'laughable', insert 'hilarious'

 

Oh, and just by the way, in regard to your claim - the heads are not 'Cast', they are CNC machined. If you had actually ever seen Jab. heads in the flesh, you'd know that. You are so much male bovine excrement, you'd overlay a Texas Rodeo paddock.

 

 

I have to agree. So where does that logic take us? I have been overhauling a Blanik - and what comes to me from that, is that there are a lot of people out there who should not be allowed within 100 yards of an aircraft - 200 yards if they are holding a spanner. Some of the butchery on that aircraft was incredible. Some of the work was very good. It hung together despite the butchery because it was such a good design in the first place.The whole basis of RAA etc was that the common aviation enthusiast was sufficiently competent to maintain his own aircraft. Are we getting to the point of disproving that?

I have a Jab that was a write-off following an EFATO that I am rebuilding. It spent almost all of its 2700+ hours life as a trainer (after being a Jabiru development 'mule'), on-the line, serviced by LAME's/L2's. My co-owner and I have dismantled, inspected, repaired etc. just about every square mm./nut and bolt on the damn thing.

 

Some of the work done - and bloody well signed-off, in later cases by an L2 who is now manufacturing aircraft - was bad beyond reasonable belief. Replacement of the front leg, leaving a near-25mm hole clear through the firewall and the steering rod-end (which is part of the rudder control system) bending against the side of the new hole to the point where the rod-end shaft was seriously bent? The rudder cable attached with the rod-end on the wrong side of the control horn, stressing the rod-end fitting? The entire rudder control system box moving on its rivets? Annual inspection reports entered and signed off - by said L2 - without airframe hours being recorded? New main legs installed with old - and in some cases, not the correct size- bolts in contravention of the factory instructions - again signed off by said L2.

 

If there is an airframe out there that has an enclosed cockpit, decent performance in all aspects, genuine and demonstrated survivability in the case of a crash, and a better 'intelligent and informed' owner-maintenance potential than a Jab., I invite its nomination. The engine, yes, requires a bit more than above-average owner/operator care, diligence and maintenance skills.

 

Jabs. aren't perfect for everybody; no aircraft is. But if you choose your aircraft on the basis of your skills, use, wallet and wants and accept the inevitable compromises that such choice imposes, then a Jab, -if it fits your user profile - is a damn good bang-for the-buck aircraft.

 

 

I heard Ian Bent is working on cowl mods to keep it all much coolerStay tuned

And a whole lot more, Deb, in a systematic research and development programme. I'm no expert but I believe you'll find that just about every 'questionable' area that is routinely discussed has been looked at and a whole lot of subtle stuff that only a deep research and development programme can discover has been investigated and considered. Information about MOST of that will become publicly available in the not-too-distant future, though some will be C-i-C, just as for any manufacturer.

 

 

FFS the better question is why is there any need to do this on a certified engine FFS.

David, I didn't ask any question. There sure are questions that Jabiru needs to address re the effectiveness of its cooling installations and I absolutely agree with that (and am in fact working on some ideas to make our Jab. engine cool far more effectively in critical areas), but there is another fundamental point that you have missed.

 

It is this: it was (at best, obliquely) suggested that Jabiru are conspiring to negate their warranty obligations, by requiring a tool 'that only the manufacturer has'. This was by someone who is self-evidently ignorant of even basic engine maintenance tools and therefore by definition ignorant of how to use them. As much as I think that piece by Rod Stiff was, to be polite, not at all well considered, his comments on a) the advisability of checking the valve guides for problems, b) indicating how to address any problems that may be determined, c) that this should not be done by people who do not have the correct equipment and the knowledge of how to use it, and d) listing what tools are required for the task, can in no way be considered a 'conspiracy' by anybody with a reasonably functioning intellect. It's up there with blaming the government for meteor strikes.

 

 

Here is a cynical view !!!!!!If I were to manufacture a mechanical device and state that it had to be serviced using a special sized tool that only I had.

FFS, run a Letter J drill down a piece of rod and set your expanding reamer using that. Both items readily commercially available from decent tool shops.

 

 

Oscar sounds educatedThat cannot be debated

He likes to tickle the nerve

 

Of the famous forumite Merv

 

He does like his Jabs

 

He says CAMits are fab

 

Our knowledge compared to his, pales

 

His vocabulary never fails

 

Makes me wonder what he is sellin

 

Is his last name really Llewellyn?

 

 

Oscar your probably a nice bloke

 

This post is meant to be a joke

 

SD - I'm truly flattered! Should I turn my cap around and get some bling? Heck, maybe I could pass for er, um, 60 in a dimly-lit nightclub. A whole new interesting world beckons!