Jabiru Bad experience

[deadstick1]

Ladies and gents, I would like to share my experience thus far with this product and the factory that makes them.
I own 2 Jabirus, a 230-D and a 160-C both aircraft have been an absolute nightmare when it comes to reliability.
The J230 suffered its first engine failure at 225 hours requiring a complete Top end, subsequently it suffered multiple component failures up until its final demise at 700 hrs with Jabiru admitting it was the failed thru bolt design that destroyed the bottom end, not once did they offer any support even after multiple requests.
The J160 suffered an in flight engine failure under 200 hours since the factory performed a top end overhaul( thru bolt failure)! since I have owned it three heads have failed due cracking and valve seat movement multiple other component failures and the nail in the coffin for this engine was a valve seat falling out at idle on the first pre-flight run up of the day all within 300 hrs of the Top end overhaul.
The factory have not once offered to help, never shown the slightest empathy or a desire to support a customer. They display a complete disregard for factual evidence when providing an excuse why a component failed.
I have been bullied, ignored and treated like a fool.
Not one Jabiru engine in my local area has made the 1000 hr TBO and not one owner would purchase another Jabiru.
The business manager has treated me with arrogance of the highest order and display's what I can only describe as an extremely deceptive nature.
The business manager flat out refuses to return my property, and will not listen to any reason or evidentiary facts stating that they must return it.
One investigation conducted by the company as to why a cylinder dropped a valve seat and had cracking, had three different conclusions over multiple days.
I regret the day that I purchased both of these aircraft, they have cost me a small fortune to keep running and I warn others to do their home work thoroughly before spending your money with them.

[ForkTailedDrKiller]

I own 2 Jabirus, a 230-D and a 160-CSlow learner? :E

Dr :8

[onetrack]

Hmmm, that's a pretty sad indictment of a company and its products - but unfortunately, you have plenty of unhappy fellow owners.
Just googling "Jabiru problems" and "Jabiru engines", will give one enough alarming reading material, to ensure that a potential purchaser wouldn't buy one - let alone two.

[VH-XXX]

Whist I sympathise with you to an extent, I don't think joining pprune to slag out one of the only Australian aircraft manufacturers and the only Australian aircraft engine will help your cause, whatever it may be.

Elsewhere on another forum you have posted the exact same information as you have here but then gone on to post an independent third party report on the condition of your engine. In this report it specifically states that the examined engine has suffered a significant heat related event, but yet you are blaming Jabiru for operator error?

The report then goes on to say that issues with the thru bolts caused problems with your engine which is fair enough as this is / was a known issue.

I would be looking closer to home to determine who is flying and potentially mis-managing your engines....:ugh:

[Avgas172]

Have to disagree with you on this one X .... I for one don't frequent any other forums at the moment, so any information is good information if it helps save my wrinkly butt .... Perhaps All the previous issues with the Jab engines have been rectified and if so all to the better for Jabiru ... I certainly support Australian manufactured products however I have had some previous experience with the product that was not up to the job and haven't been back for another go.

[Wally Mk2]

'Triple x' I reckon bloody good job this guy is handing over his experiences that way anyone contemplating buying one of these 'things' can see both sides, the manufactures side who will do anything to sell a product as after all it is a commercial venture to someone out there in the field first hand.
The heat related event/issues doesn't necessarily mean it's an operator issue could be the design itself or the guy has a 'Monday' engine/plane, plenty of them around that's for sure!

If I where going to do sumfin' dumb like buy a Jabajunk then I'd be reining in LOTS of info so I can make an informed decision.
Good on you 'Deady' for putting it out there we would all do the same if the shoe was on the other foot am sure of that:ok:

:8Dr I reckon yr the slow learner buddy:E, I mean you fly a plane all over the place that wobbles around like a drunken elephant in the sky, imagine how much fuel you would save over the life of the engine if it could fly direct to where ya wanna go rather than a little bit left, a little bit right for the next 20000 miles!:E:E

Wmk2

[Dexta]

The "heat related issue" is a common "out" by Jabiru. You can buy the J230 from the factory with steam gauges so you only have one CHT which is located on number 6 cylinder. The POH states that the engine can operate upto 350F continuously. The reality is that No. 6 is often not the hottest cylinder, no. 4 is and the CHT should never go over 270 (a tech from Jabiru was shocked when I mentioned 350 and he told me never over 270). And thanks to the RAAus rules you cannot change anything without factory authorisation if being used in a flying school, so you can't change the position of the CHT sensor, or fix the baffles etc. So no. 4 gets too hot, valve drops off and Jabiru go " ooh you cooked the engine, sorry that's abuse... No warranty.
The above is what happened to me J230 after 283 hours.

[VH-XXX]

Perhaps DeadStick can also post the independent report here so we can all make a more informed decision.

Wally, with a Jab as per other types too correct operation is very important; there have been many occurrences of students cooking engines by climbing too steeply, prolonged climbs not IAW best practices etc. If the level of diligence was applied to Jabiru engine operation as that of a turbine or perhaps a turbocharged Lycoming, much of the noise would go away. Sure sure you can say that students fly 150's around all day without issues but it is what is as they say!

Known issues and thru bolts I have no issue with, they have identified these. Unfortunately what we have here is a one-sided view at best from a disgruntled customer for which the full reasons we will never fully learn.

Dexta - the heat issue was identified by a third party and has not been used as an "out" in this case.

[Dexta]

XXX unfortunately the POH states that CHT can be upto 350F (the green arc) and if you only have one CHT Sensor the CHT can be "in the green" but one or more cylinders are getting hot. Students can be operating the aircraft by the POH but damage may still be being done to the engine.

[Wally Mk2]

'Tx' seeing as this Jab thingy is aimed at the private pilot & training market both area's may not be engineering savvy you would think that any manufacturer would design a product that can take the added stress of climbing too steeply as just an Eg, I mean sheez man has been designing infernal combustion donks for a couple of years now so it's a cop out that Jabajunk put their obvious limitations back on to the operator for the most basic environment their products are going to be found/operated, flying!:ugh:
As 1track said there's plenty of bad reading of jaba products this guys problems are but a very small part of it all.
It's all about choice, you wouldn't go & buy the first fridge you come across you'd be doing some research, that goes for everything & more so if yr gunna park ya ass in it!:-)


Wmk2

[VH-XXX]

All logical there Wal. I won't say any more for a number of reasons other than to say that I know of someone that cooked 5 out of 6 cylinders when he hired a "real" engined GA aircraft through mis-management so I don't usually blame the factory in the first instance in any such occurrence.

[poteroo]

XXX You must be living on another planet to not be aware of the many, many, many Jabiru engine issues.

If 100% of them were reported - there would be some 'activity' within the regulatory ranks. For many, and varied, reasons - most are not reported.... probably because the owner wants to onsell the problem aircraft .... asap.

happy days,

[Old Akro]

Is Jabiru subcontracting to Continental? :E

[Avgas172]

Awwww come on OA my 0300 is still powering on after 13years ....:ok:

[VH-XXX]

Poteroo I am quite aware with approaching 1000 hours behind them whilst maintaining them.

Old Akro, funny that, I was actually referring to a Continental engine above!

[Skywagon1915]

We just completed 1000 hours of flight training without a hitch + 980 on the prior engine, we do factory exchange at 1000 as a matter of course and the aircraft is run to SOPS on mostly training with some club member use.

In my 45 years of commercial flying, the Jabiru J170C, which is what I'm familiar with, is a lovely forgiving airplane and one that I'm happy to fly personally and to send 15 or 70 year old students solo in. I find it a shame that Pprune and some of it's regular contributors in particular, continuously grip about the Jabiru aircraft, engine or the manufacturer.

Why not talk about something more important, like:-

"One particular concern is that Flying Training Facilities (i.e. FTFs and SFTFs) have, up until now, been afforded the full benefits of our Member Liability insurance cover without contributing to the annual premium cost. It has also emerged that, unlike affiliated Clubs, our FTFS and SFTFs make no recurrent financial contribution towards the organisation’s running costs".

Talk about bite the hand that feeds you ... You have a greater risk to your future with this new development than wondering about J2200 or such engines, irrespective of the make !

[Ultralights]

i have read the report on the other forum, and the temps went high, but high temps for a short period doesn't have much to do with abnormal cylinder wear, or the crankshaft journal wear caused by the SB. Significant wear of cylinder barrels at 730 hours???

my 912 now has 1000 hrs, flown hard, cruise at 5200rpm, flown regularly on days with OATs in the 40's plenty of short field work with max angle climbs to 1000 agl or more. and still can see the factory hone marks on the cylinder walls.

a Rotax powerplant in a Jabiru airframe and they would almost quite literally have a bulletproof aircraft on their hands...

[rutan around]

In September last year a post entitled 'Two more Jabirus down' may be of interest to contributors to this current Jabiru engine problem post if they missed it at the time. I think the following is still relevant.


I attended a forum at Oshkosh on Jab cooling presented by Robert Gutterage. Maybe most of Jabs problems are insufficient cooling going undetected due to incorrect CHT information being presented to the pilot. Certainly Robert presented a very well researched forum backed up by hard data. Note :- He had data - not a bunch of 'I thinks'. He showed slides of what he did to solve the problem in his aircraft, as well as the 'before' data.

Apologies to Tim Juhl for pinching the following from a forum on Jabs.
(Remember-stealing articles from one writer is plagiarism----stealing from many is research.)



I attended a forum at Oshkosh where a fellow discussed his research on cooling a Jabiru 3300. He had compared the spark plug washer type CHT sensors to ones directly in the head and showed that they pretty consistently indicated CHT's about 70° cooler than actual temperatures! If this is the case, Jab operators could be cooking their engines while thinking that their CHT's were within safe limits. He ended up designing a cooling baffling system that is nothing like what comes from the factory and claimed that was the only way he was able to get the CHT's under control.

I wonder what the rest of you Jabiru 3300 operators have to say about this? I'm not flying mine yet but will be getting ready to hang it soon.

For a summary on the fellow who made the presentation check out EAA AirVenture Oshkosh - The World's Greatest Aviation Celebration (http://www.eaaapps.org/presenterinfo.aspx?id=1973)
EAA AirVenture Oshkosh - The World's Greatest Aviation Celebration (http://www.eaaapps.org/presenterinfo.aspx?id=1973)

(http://www.eaaapps.org/presenterinfo.aspx?id=1973)
It's worth looking at the last web site outlining Robert's qualifications. He's the right man for the job.

For all those who want to junk the Jab engine for as yet no clearly defined problems it would be good if you reflected on the Wright R3350 turbo compound engine used in the B29 and in the Super Constellation. When those engines were first used their TBO was typically 200 to 600 hours. Ouch
After they learned to operate them properly (essentially by running them lean of peak) they were often getting TBOs of 3,600 hours all with 1940s technology. Lycoming and Continental should hang their heads in shame.
RA

[Jack Ranga]

Buckets of sh!t. Am I hearing that it's left up to the owner to fix overheating problems? Typical arrogant, useless Australian lack of service :ugh:

[onetrack]

Jack, I don't think Australian businesses can be singularly blamed for any leading position with regard to lack of service, or poor design in IC engines. The problem is endemic, and even the largest manufacturers are guilty of it.

There are two major problems here. One is, a possible lack of substantial testing before release of a product or an altered design. The problem with many small companies is the lack of resources to carry out adequate testing - the problem with many large companies is the desire to rush products into the marketplace without adequate testing, and before all the "bugs" are sorted.

The end-user then becomes the "test-bed" for the product. This is annoying enough when the financial losses created by products failing to perform, hurt.
It's downright scary when your life is on the line - as with aviation products - due to those products failing to perform as expected.

The second problem is the standard company answer, that all product problems are the result of the end-user failing to operate, maintain, or repair the item as outlined by the manufacturer.

This is the easiest "out" in the world for all manufacturers, and one used by all of them, as well.
It is an answer driven by a (rightly-believed) fear of overwhelming ligitation following on automatically, from any admittance of a basic design fault.

It does not have to happen this way. If company managers agreed to a co-operative agreement to work with end-users, to identify and correct any faults perceived - without fear of company-destroying litigation - then the end result would be greatly beneficial to both groups.

However, I can't see this happening anytime soon - as the current culture of "deny everything, and blame the operator", is an endemic corporate culture, that has been in place for many decades - and it will take a brave manager or small manufacturer to buck the culture and prove that a co-operative effort is in the best interests of all.

[Ixixly]

Has anyone got any ACTUAL Statistical Facts on the Jabirus? So far we all seem to be relying on either:
A. "My mate Barry from down the road and myself both own a Jabiru and they both had engine problems, so it can't be our fault!!"
OR
B. "Well, mine has run alllll the way to TBO and I'm running it perfect so it must be the fault of the people using them..."

[Ultralights]

i thinks thats half of the problem, there is little in the way of facts, as once failed components are sent to Jabiru, they are never seen or heard from again. no reports, nothing.

[deadstick1]

Hi XXX,
sure its the usual default to blame the operator and I can assure you that your not the first. If I am doing something wrong then the POH needs amendment, Both my Jabs are fitted with full CHT and EGT monitoring, and the overheating event was indeed a climb out issue where number #4 skyrocketed above 200c with a CFI and an instructor at the controls.


I will paste the history of the J160 from the CASA defect report up for a read.


XXX, I didn't join PPrune to Slag off a company, I have been on here as a viewer since 2011, I retired from the military due an injury after 10 years as an aircraft engineer and 10 as a Pilot, I am working as a LAME at the moment and like to think I know the pointy end of a plane from the blunt.


I posted the info on every website I could find as I believe its a first hand account based on fact, If I save one person from making the same mistake as me then I will be happy.


I'm sure your post wasn't personal, and I respect your objective view but I can assure you I will no longer go along with the factories poor record.

[deadstick1]

History: the aircraft was purchased from Leaseair PTY LTD by me at 1318.0 ( post through bolt failure).
Prior to my ownership the engine was sent back to the factory at 1100 TTIS ( 15/08/10 for a top end overhaul due low compression and TBO, on its return and after install and runin it was fine, up until 1200.8 (100.8 TTSO) when it was noted to be weeping oil around the base of the barrels and the orange sealant used on either side of the shims was peeling away.
A call was placed to Jabiru (Don I think, called me chief) who informed that it is not U/S pending a successful torque check of the through bolts, which showed nil movement.
I was informed that the cylinders could be lifted and more orange sealant applied if it was bothering me I noted that it was just a clean up issue to the owner and it was elected to put up with the weeping.

At 1314.6 TTIS (214.6 TTSO) a pilot annotated that it did not make minimum static rpm (As per POH) so after the usual checks the carburettor was removed and serviced with corrosion under the bellows being found, this was discussed again with the factory the corrosion treated and the jetting checked, post reinstall it would still not make static RPM and I was advised that it is fine and that the factory was releasing an amendment to this requirement.

At 1318.0 (218.0 TTSO) the engine suffered an inflight through bolt failure of number 2 Cyl and was put down in a paddock, subsequent investigation revealed that The SB for the through bolt nuts had not been carried out and the time to comply had just expired 29/04/12.
Prior to release of this SB the through bolts were discussed with the factory ( the engine had only just been installed, post Top end at the time of the weeping problems) and the advice was that all engines would be done whenever they were returned for major service and not to worry about it.
So leasair elected to leave it as is and no reference was made to the SB again until after the failure! our mistake!!!

Post failure the engine was inspected, repaired, new T/Bolts, new #2 piston and cylinder, heads visually checked re-lapped and engine run in.

At 1351.2 TTIS (251.2 TTSO) number 2 Cylinder exhaust valve was leaking past the seat, the head was removed and it was noted that there was cracking and pitting around both inlet and exhaust seats so it was rejected and a new head purchased and installed.
A bore scope revealed none of the same on the other cylinder heads...

At 1475.6 TTIS (375.6 TTSO) the engine dropped an exhaust valve seat whilst sitting at idle prior to takeoff on first flight of the day, luckily the seat wedged sideways and was retained buy the valve sticking open and slightly impacting the top of the piston.

Upon disassembly (see pictures) the other two older heads show signs of the valve seats moving, the engine has never been over temped the heads show no abnormal signs of cylinder creep, it has CHT and EGT on each cylinder and the dynon EMS log showed it has always been within limits.

Other things noticed on disassembly:
1. locating dowel under the distributor drive shaft was not installed correctly and was eating into the shaft slightly.
2. Sump had a 2 inch piece of cylinder O-ring rubber sitting at the bottom and the usual carbon, a few pieces of metal.
3. the sump flange had a ding in it at the same location that it used to weep ever so slightly.
4. #4 cylinder head intake runner has a crack forming down the face of the valve boss.
5. lots of excess flange sealant inside the engine.

[deadstick1]

interestingly I just received and email from a member of a UK jabiru forum, apparently its common knowledge in the UK that the generation 2 cylinder heads crack between the inlet and exhaust ports. This may explain why Jabiru refuses to return my heads after I stated that I would like an independent report as I didn't think their explanation that a leaking exhaust on one head caused all to overheat in the exhaust valve area, co-incidentally the business manager had no knowledge of heads ever cracking before!

[VH-XXX]

the overheating event was indeed a climb out issue where number #4 skyrocketed above 200c with a CFI and an instructor at the controls.


393 deg Farenheit = 200 deg celcius.

This is a standard Jabiru CHT gauge; note the markings.

http://www.sky-craft.co.uk/acatalog/ru189.jpg

So you say that an instructor lett his happen? Normal operating temps are 275f / 135c :hmm:

With all due respect I would consider taking your aircraft offline from that flying school.

[rutan around]

Deadstick 1
I'm interested in what type of CHT sender probes you have. Is it a washer under the spark plug type or a screw into the head type?
Robert Gutterage spent a fair bit of his Oshkosh forum showing the very different readings produced by two different systems.
Cheers RA

[deadstick1]

XXX, POH states top of green arc is 180 degrees c, and operations above that up to 200c for no longer than five minutes. The aircraft has full CHT and EGT on all cylinders and a flashing light on the display once a cylinder exceeds 180. The CFI stated to me that it happened so fast the light flashed grabbing his attention and he watched the temp rocket through 200 within the time it took to advise the Pilot in command as soon as the throttle was reduced to idle the engine began running rough and they declared a PAN and conducted a glide approach to back to the field, subsequently the engine stopped just after touchdown. These guys are very professional and of note was the fact that all other cylinders stayed below limits. There was no evidence that the EMS sender on that cylinder was faulty but it was replaced anyway and was discounted by the inspector. They could not find anything wrong with the cylinder that would suggest leaning out but I relayed my concerns about the intake plenum to tube design that relies on an o-ring and goop to seal.

[deadstick1]

They were the washer under the spark plug type during this incident but I have since changed them to the latest configuration of a screw in the head between the plugs.

[rutan around]

Have you noted any variation between the temp readings you are now seeing and those you saw with the original system when flown under similar conditions?
Cheers RA

[deadstick1]

Yeah but its a new engine and an slightly different duct, it runs about 20c cooler across all cylinders

[VH-XXX]

Hi DeadStick, I've re-read your independent report elsewhere and have continuing thoughts on the issues that you have experienced.

It appears that crankcase fretting has occurred due to a loss of torque of the engine thru-bolts which were subsequently replaced under the documented SB for Jabiru engine thru bolts.

Did you maintain this aircraft engine the whole time since new?
Did you / whoever check the tension of the thru-bolts at any time that you were maintaining the engine?
Why didn't you present the engine log books to Jabiru or the independent third-party company that you engaged to review the teardown?
When were the thru-bolts replaced?

The Jabiru service bulletin was released in April 2011 where the thru-bolts had to be replaced, however your independent report was from March 2013.

For engines under 500 hours the compliance was within 100 hours or 12 months. For engines over 500 hours it was 200 hours or 12 months.)

Without the log books for the engine there is no evidence of correct maintenance at all and for all anyone knows, the engine may not have had correct maintenance.

If you were take this to an appeals tribuneral, fair trade, consumer affairs or a court of law, you'd have no evidence by which to support your case.

That's just the thru-bolt issue. Then there's the heads cracking. You have identified that 3 heads have cracked and failed. The Dynon engine monitoring instruments keep detailed information on engine performance and store it to a SATA hard drive for quite some time. Was this information reviewed in conjunction with the preparation of the report?

The report has also stated that the temperature on one head reached 180c and therefore the headS are considered scrap. This would indicate that the over-heating condition was not just limited to a single head as you've identified that your CFI reported.

I'm not getting a clear picture of the true story based on the evidence provided and feel that this is nothing more than the result of a vexatious falling-out between you and Jabiru.

[LewC]

You wouldn't happen to be trying to unload one would you 3X?

[VH-XXX]

Nope. I just like to see a balanced argument with facts from both sides rather than just a one sided social media / forum slagging campaign. (It's a pity we don't have Jabiru here to defend themselves) The nett result of these campaigns is that once a company goes broke you won't have to worry about thru bolts or heads because you will no longer be able to buy them! It's not like you can buy Jabiru heads from Superior !

[VH-XXX]

Small apologies there DeadStick but your post #24 didn't appear until just now which answered some of my questions possibly because when you posted it you were still a probationary user.


It all makes sense now that you mentioned where the aircraft came from. I wonder if yours was ever based at Bankstown. I recall a thread about some 160's at Bankstown a few years back.

[Jabawocky]

The CFI stated to me that it happened so fast the light flashed grabbing his attention and he watched the temp rocket through 200 within the time it took to advise the Pilot in command

About the ONLY thing that can cause this kind of action is a preignition event, usually from a cracked ceramic on a spark plug. Or a tiny slim chance of a helicoil tang protruding into the head.

Jab heads do not have helicons (or they did not long ago) so a spark plug, most likely dropped caused this. Rough mechanics?

[Wally Mk2]

...hey I was wondering where you have been Jabb Dabba Doo, we need yr expertise here buddy:ok:

"Deady" you don't need to justify or explain anything to anyone here buddy, you posted yr experiences of said jabajunk & if anyone was going to buy such a 'thing' then it's up to them to take ALL info in:ok:
If I heard just one tiny bit of bad info regarding any product I would then do my own homework, not listen to anyone else experiences trying to cover up what you have had.


Wmk2

[motzartmerv]

Yes, i was at the controls when this particular engine fried.
It happended within a few seconds and there wasnt much i could do about it.
I am a little tired of hearing about the "operator error". Look dudes, the FACT is, this plane was always operated within the specs of both the maintenance manuals and the flight manuals. It cooked in seconds and has yet to be fully explained.
If this failure was some sort of random out of the blue failure then I wouldn;'t have much more to say about it. But its far from random, the donks are rubbish. Pure and simple. yea sure, blame the operator or the maintainer, but sooner or later this Jabiru copout will have to be answered to with facts. When you do try this you are greeted with the sort of underhanded BS that deadstick has posted here.
The simple solution for my school has been to go back to a real aeroplane engine. And low and behold.....problem solved... No more random failures and rubbish factory attitudes.. Just constant, reliable, trustworthy performance..
Sorry jB, BUT WE TRIED TO USE YOUR PRODUCT. BUT IT FAILED ..MISERABLY..
PS. having operated half a dozen of these things over multiple years in a variety of conditions, i believe my statements are backed by actual experience, and not just hearsay etc.

[motzartmerv]

I should add, I was referring to the J230 engine overheat. Not the4 J160 with the lemmon engine.

[VH-XXX]

Motzartmerv, any idea why the log books weren't sent to the engine facility and third party engine inspector?

It's like sending in your car at 80,000kms with no books and asking for a warranty claim on the engine.

[motzartmerv]

Not sure XXX. Id be very reluctant to send anything to the factory that i wanted back:)
Thank you for the positive comments regarding putting the planes on line with another school. The owner just needs to advertise for a school that uses a crystal ball to know exactly when a normal operating engine will go super nova in 5 seconds time huh?
if your looking for a copout on not IAW with jab manuals then your barking up the wrong tree.
This maintainer was ANAl about that, and even helped jab FIX some of their discrepancies in their manuals which we discovered existed after following them during install and finding that they had been put in backwards. Very clear, simple F@#up by jabiru. Discovered after yet ANOTHER component failure.

The logbooks on all these aircraft have been inspected on several occasions during RAA audits and insurance claims.

Cheers

[deadstick1]

XXX your confusing two different aircraft here mate, The independent report is for the 3300 in my 230, the reason there was no log book at jabiru when it was independently inspected was because it wasn't requested, Jabiru did however request extracts from it! Yes of course the engine was maintained by the book and torque checks of the thru bolts conducted at the settings advised by the factory (if I recall somewhat lower than initial settings)


Only number 4 head from that engine reached a temp above 200c, shows how invested Jab are in the facts when plying their facts on failures.


The cracked heads and the valve seat failure are from the 160 all within 300 hours from Top end overhaul and no this engine was never at Bankstown since they O/H'd it.


Its not a falling out with Jabiru mate, I am posting my experiences as stated previously to inform people, yes they are entitled to make up their own mind either way and im not trying to sway it, just the raw facts!


I am so sick of people wading in accusing a Jabiru owner of incorrect maintenance or operation, give me a break please its getting old.

[zanthrus]

I have had 4 engine failure in my 6600hrs experience.

All four in Jabiru 2200 aircraft.

Two engines cut out short final when power reduced to idle for landing.

One cut out during a stall practice at 4000ft in training area accompanied by a wing drop at the stall. Exciting! Restarted ok.

Final one was loss of oil pressure in circuit on downwind. We landed immediately and the engine started vibrating wildly on touchdown.
Subsequent investigation found that on downwind the oil pump jammed up with pieces of valve tappet adjuster screws that had shattered, and engine went completely out of timing on landing.

You will never ever get me back in that piece of $hit wing cracking, engine failing, random flap retracting, small wheelled uncomfortable aircraft.

Z.:ok:

[deadstick1]

Zanthrus, can I use that bottom line? very funny, thinking of ideas for side stripes on the 160...

[deadstick1]

XXX,
heres two of the reasons Jabiru gave me for the J160 heads failing, the other was to accuse me of running an additive. I quote Sue woods the business manager:-


"The word from the engine section regarding the heads is that there is evidence of overheating of the exhaust port areas probably from leaking exhaust pipes. This overheating has resulted in the valve seats dislodging and valve stem damage. They suggest the installation of EGT monitoring as an early warning for leaking exhaust pipes. Also carburettor jetting can be checked against the EGT measurements on the Mogas, Avgas and mixture of Avgas and Mogas. The cracks in the heads may have been caused by the overheating though they don’t appear to have contributed to the engine failure. For any more information speak to Mark in the engine section."


XXX, point of note a full brief of equipment fitted and conditions at the time was sent, they missed the fact that it had the desired sensors, also if you read the report into my other engine, the 3300 you will note that Jabiru state that the seats will start to fall out at 250c. also they found that one head had an exhaust leak at the flange, gripping at straws if you think that effected all heads... So I politely pointed out the inconsistency in their conclusion and got this:-


"Hi Chad

The engine section has examined the heads and the piston and cannot see any manufacturing defect that has caused this damage therefore we will help as far as providing the 2nd hand heads as quoted. If you want to send us the EMS data file we would be interested to see the EGT measurements against what fuel was in use. "


I have considered driving the 7 hours to get the EMS file for them, but I can guarantee it will show that they have been kept within limits! further all Jabiru would say if I tried to use that as evidence is that its a non calibrated instrument.


Sue has informed me that they will not be returning my heads, only after I requested them back for a third party to inspect and report on, she quoted her requirement to hold them in quarantine for one year so CASA can inspect. I provided her with this from the section head of defect investigation at CASA:


Hi Chad,

This email formally notifies you that under Civil Aviation Regulation 52B(3) that your Jabiru cylinder heads are not required to be kept in a state which allows CASA to investigate the defect.


Still refuses to return my property.

[motzartmerv]

Why would they need a log book to explain how and why an engine failed? Its simple. They pull it apart, find the broken bit. The blaming of the operator (need for log book) would come later yea? Thats the usual routine isnt it?
"oh, youve overheated it"
" umm, no I havnt, I have 4 channel EGT/CHT for entire life of (rebuilt) engine which clearly shows always in specs."
"Oh, well, in that case, you used the wrong fuel additives"
"Ummm, no, i dont use fuel additives"
Oh...fair enough, well, then im afraid youve overheated it"..
"Ummm..havnt we been over this?"..
"oh yea, sorry, i got confused who i was talking to. You must understand we deal with a lot of these failures every week, I got confused"
"ok, so can you please tell me why my factory engine died at 300 hours?"
" Yes, we probably can..But..Not right now..We want to quarantine the parts so casa can see them...one day..maybe."

"Ok, just let me know please..Now, can you put me through to the sales dept..i need to buy some new parts to fit to my factory engine that doesnt work anymore"
"yes certainly sir"


While you may think this is a joke, i assure you its not. every part of that conversation I have witnessed first hand.

[VH-XXX]

All four in Jabiru 2200 aircraft.

Two engines cut out short final when power reduced to idle for landing.

One cut out during a stall practice at 4000ft in training area accompanied by a wing drop at the stall. Exciting! Restarted ok.

I chuckled when I read this, so you have had one genuine engine failure that can be attributed to the condition of the engine.

Adjustment of the idle stop is hardly a fault of the engine or engine manufacturer !

[motzartmerv]

Yea, hafta agree. It seems your engines were idling to slow.
I once did the testing for a Jab powered homebuilt. For some reason, the engine would idle normally on the ground, but in flight would idle down and stop. Was strange and counter intuitive. I cant recall the reason. Sorry, getting old..

[Jabawocky]

I have considered driving the 7 hours to get the EMS file for them, but I can guarantee it will show that they have been kept within limits! further all Jabiru would say if I tried to use that as evidence is that its a non calibrated instrument.

Well I would happily look at it for you, but can I say that there is no such thing as an EGT within limits, except when talking about a TIT, but that is not relevant here.

Have you been using Avgas? Mogas? and which sort and where from?

And just in case you are wondering ....which do you think has the highest EGT and which is the better off the two?

And just before you think I have any involvement with Jabiru, I do not. But I might be able to offer rational understanding of engines the data and they fuel used. ;) Gidday Wally! :ok:

[deadstick1]

Jabbawocky,
mogas, higher EGT than avgas.

[Two_dogs]

M,

For some reason, the engine would idle normally on the ground, but in flight would idle down and stop. Was strange and counter intuitive.My best 'guess' would be induced prop drag due airspeed. I used to operate a C206 that would slow the idle when turning right due (I'm told) to gyroscopic propeller influences. Never occurred when turning left.

An aerodynamicist or engineer may have a more qualified answer.

[rutan around]

Deadstick 1 you have one more guess. I'll let Jabba explain why. Cheers RA

Hint:- Compare what happens after the spark event using the two different fuels. Especially look at peak pressure and where it occurs and what happens to CHTs The timing and RPM should be the same for both fuels when you do the comparison.

[Aussie Bob]

Adjustment of the idle stop is hardly a fault of the engine or engine manufacturer !

Yea, hafta agree. It seems your engines were idling to slow.

Nothing like judgement by your peers :ugh:

The two J160's I have time in both have a peculiarity. If the idle is set correctly and a ham fisted pilot heaves the throttle shut the engine stops. If the idle speed is set high so the engine can't stop with a hard yank on the throttle then excessive braking is required or you need to instruct to pull the throttle very hard and keep the pressure on. There is a flex in the system somewhere that I have NEVER encountered in any GA aircraft. Gifted engineers have looked at these two aircraft, the best they come up with (failing modification) is a compromise, high idle or an engine that can be stopped by hauling hard on the throttle.

I know the problem Zanthrus, I have seen it, having a prop stop on final or on the runway is not really my cup of tea.

That said, both aircraft have had no engine problems, both have 2200 hours and both have had engines replaced (in lieu of a top overhaul) every 1000 hours.

[motzartmerv]

hey Bob. No judgment mate. Just a possible explanation to his woes..Which you subsequently provided further evidence for. Judgment? or discussion..?

Ive not come across that problem in jabs. You must have some strong handed pilots there, pulling on that throttle.

[Jabawocky]

Rutan around..... :ok: Good work there. Clearly not rutanaround at the back of the class were you. Unlike a couple of other ppruners :E

deadstick
The shorter latency of mogas Vs Avgas means that the peak pressure is higher and so is the CHT. Neither of these things is optimal.

The spark timing is fixed at 25DBTDC and being a direct coil on the flywheel system this will mean the spark (in theory) will fire sooner than that of a conventional magneto, but only a little. It could be said that the plugs location partially offsets this, but I do not know that for sure. (Flame front propagation).

High CHT, poor fuel quality, and with MOGAS there is not guarantee, there could be increased peak pressure and thus CHT. Add to this induction leaks and or the ordinary fuel distribution and how you know what was happening.

My suggestion is that with Mogas compared to Avgas all things being equal, you had higher CHT and lower EGT.

There is a large difference in Octane rating. So specifically which Mogas were they using and from where?

So getting back to the failure with a rapidly rising CHT and the two instructors on board, have you any photo's of the failed cylinder?

[Jack Ranga]

Hey := hold on, I was up the front :ugh:

There might have been a bit of rooting around but I got the most important question right :ok:

[motzartmerv]

Do Jabiru certify mogas in their engines? If so are there any modifications needed (IAW with the maintenance manuals) to account for this issue?
Another question. How do other aircraft engines that allow both types of fuel handle the issue? Im assuming the engine manufacturers have similar or dare I say it, better knowledge about these problems?

[Old Akro]

Another question. How do other aircraft engines that allow both types of fuel handle the issue? Im assuming the engine manufacturers have similar or dare I say it, better knowledge about these problems?

There is a bucketload of material on this. Try this to start. You'll find more with the EAA, possibly AOPA and I think the Cafe Foundation.

Petersen Aviation | Auto Fuel STC (http://www.autofuelstc.com/)

In short (aside from octane issues) Mogas compatibility has to do with fuel pump configuration and fuel line fitting metal composition. The engine itself doesn't care much, its all about getting it to the engine.

[VH-XXX]

It is impossible to pull the throttle rotating mechanism past the stop located on the side of the carburetor, basic physics that one!

If the engine stops when the throttle is pulled out of the dash regardless of the strength of the pilot(s), then the idle stop is incorrectly set. Pretty simple really.

What will be wrong in the instances of stoppages mentioned above, is that the location of the cable assembly is incorrect both where it passes through the firewall and also through the holder attached to the carby. In all honesty if your mechanic can't get this right, they should stick to lawn mowers and I'm not referring to ultralights either. Failing that the problem will go away after replacing the throttle cable. I would be more than happy to demonstrate the correct fitting of the cable whenever I next pass through wherever this problem exists.


You will never ever get me back in that piece of $hit wing cracking, engine failing, random flap retracting, small wheelled uncomfortable aircraft.

Would love to hear more on the wing cracking and random flap retraction. Both of those if reported would probably warrant an SB. As for random flap retraction, they are either manual flaps on an old LSA55 or electric in the J160 onwards and short of some shoddy maintenance I can't imagine why the flaps would randomly retract. No wonder these aircraft are getting a bad name when mechanics can't seem to look after them properly.

[motzartmerv]

Yes yes. I get that. But, im saying that clearly there are engines that are designed to run on both types of fuel. My question is, what, if any measures do operators of these engines have to take when running the different fuels to account for these problems.. Apart from the rotax schedule of extra oil changes. Whats the difference. if its enough of a difference for some of you to blame the fuel for overheating the engine to FAILURE, then surely it would be enough of a difference to warrant standardised handling of the engines with different fuels.. of which there is non that im aware. Please tell me if im wrong.

[Old Akro]

Heat comes from energy. Its about how much power the engine produces and how effective the cooling, not the fuel that supplies the energy. I have only half been following this thread, but I think some of the failures may not fit the symptoms. I struggle to see how fuel type would play a role. Ignition timing might (come in Jaba).

As a rule of thumb car sump oil runs about 20 degC hotter than the water temp. Modern cars can easily run over 100 degC, so an acceptable operating temperature for oil is 120 degC (say 250 degF) for as long as you like. Use Synthetic and you'll go a lot higher. Higher temperature causes mineral oil molecular chains to break down. A modern car will happily do this on a synthetic blend oil for 30,000 km which equates to about 150 hours (an overall average of 50 km/h is a reasonable guess for an average suburban based driver with a mix of city, suburban and freeway driving). The Jabiru (I believe) uses automotive oil not the old mineral cr*p that certified engines use.

Oil is a major part of the cooling of any engine (even water cooled ones). I forget the proportion of cooling done by oil, but it might be circa 20%. Automotive oil will have better " wetting" properties and I would expect would transfer heat more effectively that aviation oils.

We should be able to design & build engines to cope with this and I struggle to see how through bolt issues are related to operating temperature. If I were to investigate this, I'd start by looking at the operating practices.

As I said, I haven't really paid full attention. These are off the cuff ideas. I might have something wrong.

[zanthrus]

Hey XXX

Glad I gave you a chuckle and I agree engine cuts on idle power may not be classed an engine failure. I can tell you it was a big surprise and very sudden. It was not as a result of ham fisted yanking closed either.

The flaps were manual on left side of roof. Half a broom handle and a bush which kept popping out of the hole holding the flap setting. Sudden bang and loss of lift which really scared the student in left seat!

Wing root cracks starting in windscreen. I was told that is just the gel coat she'll be right. Still not a good look and I never totally believed them. I have never seen this type of defect in other composite ga aircraft. Seems ultra light are a different breed.

Z!

[motzartmerv]

Yea, sudden uncommanded flap retraction makes the aeroplane unserviceable in my opinion. If you flew it in that state...more power to ya brother. :)

[Jabawocky]

JR

Hey hold on, I was up the front

There might have been a bit of rooting around but I got the most important question right

You did indeed. Nice to survive that test! Rutanaround was in the BN class though. More ratbags per sq M.....ohh hang on, no there were a lot from SA.

Merv, they do say they are OK on Premium Mogas, and they may well be. They approve them for 98RON, but I am not sure nor does it really matter about what they were certified with, but it would have been avgas at the time.

The engine itself doesn't care much, its all about getting it to the engine.
Old Akro The engine may not care much, but it does notice, but just like the STC's for many of the small HP carby engines, the engine will will see a change in the thetaPP no mater what. The fuel does not know the engine. It may well be fine on the PULP.

OA, think about this a bit more especially with hot heads. ;)

The jab engine was designed around 100MON avgas. It may well be fine on BP/Caltex 98 and they do say in factory SB's that 95+ is OK, but lord only knows what was being run in it so far in this thread, hence my question.


PS : OAIgnition timing might (come in Jaba).

The latency off the fuel affects the effective timing. In other words the sparks go off at 'X' DBTDC but the peak pressure and ThetaPP are directly affected. Longer latency of Avgas will mean lower ICP as a result of the later ThetaPP. As for heat and the energy produced, yep 100% agree.

[Old Akro]

Sue has informed me that they will not be returning my heads

The heads are your property. They are not entitled to keep them. Period. I'd give them a solicitors letter and a deadline.

If you wanted an expert witness, there are a few guys from the engine labs of Toyota, Holden, Ford & Orbital that would be well qualified. I think you'll struggle to find an experienced engine calibration guy outside of Melb (or Perth for Orbital). For the purpose of preparing for a potential court appearance, I'd stick with a professional engineer.

[Old Akro]

OA, think about this a bit more especially with hot heads.

I thought the hot heads were on the Dick Smith thread???

I'd argue that the head temperature is a product of the power output (& cooling airflow) and largely independent of fuel. Indeed Mogas probably has a lower specific energy than Avgas, so might be a bit easier on the heads.

We must catch a beer. I'm in Brisbane in early Feb.

[Old Akro]

I should add that I suspect part of Continental's problem is poor valve seat design which does not transfer heat from the valve to the head well. Thus the valve gets too hot and the seat wears causing valve recession. So, that's an area that might deserve investigation on the Jabiru engine.

[motzartmerv]

The engine we are talking about was run on 98 Mogas.
Was this what caused the valves to fail?

[Jabawocky]

Merv, not the valve failure needs to be determined as to how it failed. Valves generally fail due to poor machining of the head/valve seat and the guide. Valve guide wear through rocker geometry or through poor fit and then cargo or lead oxybromine ingress, then sloppy guides mean a rattly valve and then the head breaks off.

To make matters accelerate the CHT will not help if it is very high. There is no doubt the shorter latency of mogas Vs Avgas will have an impact but I doubt it has a serious impact if the cooling airflow is sufficient, but it does not help. There is a big difference from Avgas at about 110RON and 98RON that may well be a bit lower.

Getting back to the rapidly rising CHT, I am not saying it could not ever happen but a rapidly rising CHT is indicitive of a preignition event and not a valve failure.

Valve failure is not normally associated with a rapidly rising CHT. It can often be seen coming with the EGT races in the EMS. But even there not always. We had a C340 owner in a class once with a failed valve and no warning. That is a TSIO 520 Conti.

So was this failure a preignition event or not?

I wonder what the oil change interval was?

I think the valve geometry could be better, the guide material better. Are they post reamed and nice fit?

So many variables and the same is said for the maintenance of them. Don't get me wrong, my IO540 is my preference but many a jab engine does not get the life it should from external factors. But on the other side of the coin the cir clip events showed how easy things come undone too.

[Old Akro]

1.
We had a C340 owner in a class once with a failed valve and no warning.

2.
That is a ...... Conti.

3.
QED

[motzartmerv]

Jaba. There are two separate engines being discussed here.
The J230 was a CHT overheat event. I highly;y doubt it was pre ignition or detonation as the engine gave no rough running sympotm at all, The only indication was the flashing light warning me the CHT was over 180 deg's. That was late upwind, about to turn xwind on a normal 80 kt climbout on a 28 deg day. By the time the turn was completed the CHT was 210 deg's, then 220. That was when I levelled out, reduced power and returned to the strip.Where it subsequently stopped.
My questions relate to the valve failure at 300 hours in the 2200 with an engine that has logged history in 4 channels on CHT and EGT. None of which show anomalies. no overheat issues indicated. jab quote that valve seats start dropping out at 250 degs (see engine inspection report).
When we have one engine that fails at 220 degs, and jab saying 250 is where the seats let go. Why, has this 2200 engine dropped a seat with NO over tempt issues.
Thats the 64000 dollar question

[Jabawocky]

Notes inserted below in RED

Jaba. There are two separate engines being discussed here. Take it easy on me
The J230 was a CHT overheat event. I highly;y doubt it was pre ignition or detonation as the engine gave no rough running sympotm at all, With all respect, it is apparent you do not clearly understand what either of these events actually are, and no you will not notice rough running at all in either case, until preignition kills the cylinder The only indication was the flashing light warning me the CHT was over 180 deg's. That was late upwind, about to turn xwind on a normal 80 kt climbout on a 28 deg day. By the time the turn was completed the CHT was 210 deg's, then 220. Could have been a lot of heat build up from some unintended machining going on, but this is pretty much how preignition goes That was when I levelled out, reduced power and returned to the strip.Where it subsequently stopped. Yep that too. But it may have been a circlip problem (refer SB) and subsequent chewing up metal.

My questions relate to the valve failure at 300 hours in the 2200 with an engine that has logged history in 4 channels on CHT and EGT. None of which show anomalies. no overheat issues indicated. jab quote that valve seats start dropping out at 250 degs (see engine inspection report).
When we have one engine that fails at 220 degs, and jab saying 250 is where the seats let go. Why, has this 2200 engine dropped a seat with NO over tempt issues.
Thats the 64000 dollar question Add some more zero's on the end ;) So the 220d failure, was this a valve too? How did the 300 hour one fail? What were the guides like? I am not at all defending the Jab engine build, just trying to help in the understanding. 250dC is too hot to run the engine at but should not have seats falling out of the head :uhoh:

[rutan around]

Another question. How do other aircraft engines that allow both types of fuel handle the issue? Im assuming the engine manufacturers have similar or dare I say it, better knowledge about these problems?
Generally the engines approved for lower octane fuels have relatively low compression and were originally designed for low octane fuel. Apart from lead polution higher octane 100LL does no harm as the slightly slower combustion event finishes a few degrees later safely after top dead centre. Peak pressure is well after TDC making it lower and easy on the valves and cylinder heads. As peak pressure occurs in a good place mechanically very little power is lost.

When lower octane UL fuel is used in engines designed for high octane fuel bad things happen.The spark occurs where the factory set it. The time from spark to completed combustion is shorter with UL so peak pressure occurs earlier in the cycle sometimes before the piston reaches TDC. This is very hard on the engine and it's a credit they hang together as well as they do.

One way to help the PP to occur later is to use higher revs. Now this is all very well for Jabba with his fire breathing monster engine fitted with a constant speed prop but for us mere mortals the only option is to lower the nose. It's unfortunate that engines fitted with fixed pitch props reduce revs just when they are working hardest ie in climb.The cooling air decreases and the PP occurs in the worst place creating more heat. The combination creates excellent conditions for detonation but by using low octane fuel detonation is not very well resisted and can quickly get out of hand.
Automobile engines get round the problem by having knock sensors which retard the spark in the above scenario.
Don't ask me past this point as the rest of the seminar was after the long liquid lunch and Jabba's dulcet tones put me to sleep.http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/tongue.gif
Cheers RA

[motzartmerv]

Detonation doesnt cause rough running?

[Ultralights]

not normally, might create an unusual sound as it get to heavier detonation, but mild detonation usually goes un-noticed.

[motzartmerv]

the 2200 (J160 ) Failed on startup. ran rough and spluttered. pulling ther prop through by hand we found a cyliner to have zero compression.

[rutan around]

Not till it gets out of hand. Some big bore turbo'd engines live with mild detonation for a lot of their operation. The high octane fuel prevents it running away (generally)http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/boohoo.gif

[Ultralights]

from my understanding, the 2200 was the failed valve seat? the failure of the valve seat is irrelevent to EGT, or fuel type burned. and most lilely a manufaturing defect, even though Jabiru claim its valve seats fail at 250degC, which the 2200 never reached.

[Jabawocky]

merv

as pointed out above detonation is unlikely to be noticed in an aircraft engine. I doubt the Jab engine will detonate anyway, although given the right circumstances with low octane, hot temps etc you might be able to. But not easily.

Preignition you will likely not hear or feel much there either until you have a trashed piston.

Your description of what you found is not very diagnostic at this level so maybe none of our collective somments are of any use.

The likely issues are valve guide wear then damage to the valve as a result. High temperatures will not help either.

Complete lack of data along with so many experts having their opinion along the ay mean finding the truth is almost impossible.

[deadstick1]

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 160, dropped a valve seat whilst sitting at idle after the pre take-off mag checks. Upon inspection the cracks in the heads were discovered.


"The word from the engine section regarding the heads is that there is evidence of overheating of the exhaust port areas probably from leaking exhaust pipes. This overheating has resulted in the valve seats dislodging and valve stem damage."


The heads show cylinder creep (ridging) only around the exhaust port.


Fuel used primarily is Caltex 98, but when away, fuelling at other strips they use avgas.


Jabba, My experience on these engines and I have opened up a few, is that Avgas leaves deposits everywhere, the common issue I have noticed caused by it is ring sticking.


I have tried to post pics but cant figure it out, drop me your email and I'll send you some.


Request: can we keep it civil? accusations that the standard operating advice from Jab has not been followed are unfounded and completely wrong. It has been maintained and operate within the guidance and documented requirements set down by the manufacturer.


I get accused of this by Jabiru, always when asking for some kind of warranty or an explanation why their product isn't performing as it should.


But for the life of me can't understand why others have to belittle or be suspicious even after multiple denials, I have nothing to hide I have done everything that the factory has asked.
(My next step will to have a monk bless the bloody thing in hopes of 1000 trouble free hours).:rolleyes:

[deadstick1]

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!

[motzartmerv]

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.

[VH-XXX]

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%20Bulletins/Engine%20files/JSL007-4_Fuel_Guidance.pdf

DeadStick1 Fuel used primarily is Caltex 98, but when away, fuelling at other strips they use avgas.


(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.

[deadstick1]

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!

[motzartmerv]

Wow..shandies now. What else can we come up with?

[Hempy]

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!

[MicroLightNZ]

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.

[Jabawocky]

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.

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.
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? :confused: Does not add up does it?

[Two_dogs]

Jaba,

Oil changes every 25 hours and not 50...
Head torque checked every 25...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.

[VH-XXX]

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!

Nah I've got nothing to do with the factory; I'm happy with what has been eventually posted. First off was what looked like a one-sided grudge against Jabiru and their customer service. Now what we have with the quoted emails from Jabiru plus more information on the operation and history of the aircraft, readers are now able to make an informed decision for themselves and decide whether or not do deal with Jabiru or use their products in the future.

Those that haven't yet seen this might find it interesting:
New Camit Aero Engines | CamitAeroEngines (http://camitaeroengines.myshopify.com/pages/new-camit-aero-engines)

[motzartmerv]

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.

[Two_dogs]

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.

[Ultralights]

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.

[rutan around]

Jabba
How does a run away CHT relate to the bottom end being destroyed?
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

[Ultralights]

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.


if it was fuel/mogas related, then wouldn't we see the similar failures within the rotax fleet, which preferred fuel is Mogas. or is the situation avoided with the higher revs effectively moving peak pressures thurther from TDC? (which is why i run mine at 5200rpm)

[VH-XXX]

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?

[rutan around]

if it was fuel/mogas related, then wouldn't we see the similar failures within the rotax fleet,
Not if the Rotax timing is set up for Mogas .Then adding Avgas has the same effect as slightly retarding the timing which isn't hard on the engine unlike advancing the timing which is very hard on them.

[motzartmerv]

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.

[deadstick1]

XXX,
Just sent the full PDF with pics to Jaba

[Jabawocky]

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

[Jetjr]

There are a wide range of different "Jabiru" engines including newer variants from those who actually make them. Some core improvements I think. First is to return to older solid lifter design, new cylinders and some head upgrades.

Isnt a key problem with Mogas the longevity and variable performance this brings, let alone other more detailed problems outlined by others

I have an 800hr 3300 with very few problems, Jabiru have always been excellent to deal with.
Always fly with an eye for a landing spot.....doesnt everyone flying singles?

They arent Rotax 912 or 914, few pretend they are, these Jabiru cost way less to own and operate, an entire brand new 120 hp engine is ~$19K.
Cheap and easy maintenance doesnt always equal well done and sure theres some conflicting service and operation data out there.

As far as DS problems go, maybe Im mixing incidents but heres an engine running on mixture of fuels, overheated (something gone very wrong), significant SB not carried out. At least a few issues piling up. What did you expect Jabiru to do? Seems they may have offered reco parts.

How recently have you gone back to Nissan or Toyota with a fatally busted engine and been received warmly. How about a LAME after a rebuild?

Jabiru do use std W100+ oil, significant work has been done to look at better options in the future, hopefully correcting some problems.

[motzartmerv]

Good onya jet. Glad jab have treated you well, but like you said, you havnt had any issues with your engine yet ay? So applaes for apples..your selling oranges.
When did DS say he ran a mixture of fuels? He ran 98 octane. Very rarely the tanks got topped up with AVGAS. in the 300 hours in question, probably 30 or 40 litres TOTAL avgas.
What SB was not carried out on these two engines?
As far as im aware jabiru haven't recommended W100 oil for some time. I could be wrong but i recall them insisting we change to 15/50 some years ago.

[VH-XXX]

Aeroshell 100 for run-in.
W100+ for continued use.

Don't confuse the W's and the +'a as there is also a W100 with no plus.

[motzartmerv]

From the current maintenance manual for the 2200 engine.

Aero Oil W Multigrade 15W-50, or equivalent
Lubricant complying with MIL-L-22851C, or
Lycoming Spec. 301F, or Teledyne –
Continental Spec MHF-24B

[deadstick1]

Jetjr,
Well here we go again hey?


"As far as DS problems go, maybe Im mixing incidents but heres an engine running on mixture of fuels, overheated (something gone very wrong), significant SB not carried out. At least a few issues piling up. What did you expect Jabiru to do? Seems they may have offered reco parts."


No mixture!
Mate the engine never overheated!


Your right! under the previous owner the thru bolt SB was not carried out, this was because Don Richter from Jabiru advised them that it wasn't required and that all engines were being done when they were returned for overhaul! They missed the deadline by 4 days! pretty telling that it snapped one under 200 hrs from Top end overhaul though!


The 3300 on the other hand did have the SB incorporated, and in the report into its demise at 700hrs Jabiru themselves explain that the SB destroyed the bottom end due to closing up the fretted crank cases with the extra torque. So that engine wasn't fit for purpose from the get go!


I for one am not expecting any Jabiru warranty ( there's a reason it was reduced from 500 hrs to 200), what I am expecting though is my consumer rights to be upheld! To talk on The simplest of consumer rights and one of the many basis for claim, neither engine could be described as fit for purpose, of which based on the log books and correspondence a very expensive lawyer has said they are in breech and is preparing the case.


I am so happy for you that you are getting a relatively good run from their product, this thread is about the other 95% of people who are getting shafted day in and day out by them, but congrats to you.


By all means keep pointing your finger, one day you may find it pointing back at you!


(I am sorry this seems a little poorly toned I usually enjoy reading your posts)

[deadstick1]

XXX,
hope you don't have any failures, LOL cause this will be the reason after the factory investigate:


"Aeroshell 100 for run-in.
W100+ for continued use.

Don't confuse the W's and the +'a as there is also a W100 with no plus".


meant to be Light hearted in tone!

[motzartmerv]

Lol.Lets hope insurers dont read prune huh?..Or we'd all be stuffed..

[Two_dogs]

Jaba,

I was in no way questioning your opinion, or inferring you were in any way factory aligned or opinionated. In fact I look forward to your input; you seem to know what you are talking about in most cases.

I just feel that with current technology, better design and manufacture is possible if the dollars are spent wisely. This may include stronger (more expensive) alloys used in component production. If a head needs torqueing down every 25 hours, is this the cheap retaining bolts stretching or the cheap alloys compressing?

Of course it all costs motza dollars in certification, but surely the same cost for any level of design; just higher design and build costs? “Build it and they will come”

This is purely my opinion; I hold no engineering qualifications at all, but have successfully built more than one high performance V8 engine, gearbox, limited slip differential, auto transmission etc. This was all done by research, (Haynes Manuals, God bless em) and following the accepted current engineering practices. Of course, I had an advantage, I was using superior parts with a proven history. I did not have to design or manufacture them myself.

As an aside, I grew up on Cleveland and Windsor 302 and 351 engines. I can still remember the beautiful note they produced running on a twin 2’’ sports exhaust system, particularly the Ford XY GTHO Phase III shifting into top gear some five miles (remember them) out of town. :ok:

[Jetjr]

95% owners with problems?? Is that another evidence based claim. Id point to 95% being happy and 5% complaining loudly and on some cases rightly so.

There are plenty of things jabiru could do better and the Latest tech manuals are pretty good, compared to originals. An issue is the adjustment and changes with no comms to owners and maintainers. An example is the 15w50, was deleted a year or so ago as Shell (or someone) decided it was a very poor choice, so back to W100+ and problems it had. Who knew, i learnt from a presentation @ Ausfly.
Its going to change again soon.
The through bolts were being replaced for free if you took the ac back to bundy, the tightening of the bearings confuses me as torque was the same afaik.

Re the fuel, talk to jabiru and reading documents Avgas is the preferred fuel mainly cos quality is stable. experience shows me what you get from Service stations is pot luck and pretty common to get bad batch.

Many of the current problems have developed with newer hydraulic lifters implemented and points to preignition to me.
Jabiru will still sell you a zero time solid lifter type now so will Camit, trouble is the LSA rules prevent it in 24 aircraft.

[Old Akro]

xperience shows me what you get from Service stations is pot luck and pretty common to get bad batch.

There are some other threads where Jabawocky and I have debated this in detail, but I maintain the Australian refined fuel has quite good "batch control".

The bigger problem issues are:
1. companies who import fuel bought on the international spot market
2. service station sites adding cheapening chemicals
3. Service station sites with old ingound tanks which let in contaminants

If you are going to use Mogas stick to 98 octane fuel from a high volume Shell, BP or Mobil site. These are the only companies who refine in Australia and therefore have a consistent supply line. All other service station brands are buying fuel from somewhere else that is unknown.

[deadstick1]

"95% owners with problems?? Is that another evidence based claim"


no that was a stab (frustration can do that to a usually nice bloke)


By stating "is that another evidence based claim" are you inferring that what I am saying isn't based on evidence or fact?


Jetjr,
I am happy that you are having a great run with your Jabiru's and the factory's support I really am that's not sarcasm.


This however is not what I have experienced, I have done nothing wrong in the operation of these aircraft, they have been by the book.
If I was an outsider looking in I would probably default to a surely they can't be that bad, after all aren't the certified to fly over populous areas?


But a good indication that there is multiple problems out there is the constant revision and changes to just about every part of operating these aircraft and engines.

[deadstick1]

Jetjr, "Many of the current problems have developed with newer hydraulic lifters implemented and points to pre ignition to me.
Jabiru will still sell you a zero time solid lifter type now so will Camit, trouble is the LSA rules prevent it in 24 aircraft"


The hydraulic lifters are a bit suspect, I have seen dings in the tops of pistons from what I can only suspect to be "pump up" or incorrect preload on the lifter.
I was told by camit and I quote " yeah the hydraulic lifter engines haven't been very good".


Having said that the roller cam engine now in my J230 seems to be going well, but its early days yet.

[Wally Mk2]

Amazing the amount of press this subject has created, obviously it's well known the problems of these engines. I also note a Jab 4 sale on Ebay with a little over 400 hrs assuming from new & has had all the cylinders replaced already.
If I owned a new Lyc or Conty that needed that sort of heavy maint then I'd be worried!
This thread does make for rather in depth reading with some very in depth knowledge kicking about:)

Wmk2

[ForkTailedDrKiller]

Yeah, I've had a Jabiru bad experience - flew with Jaba in one! :E

Dr :8

[VH-XXX]

One defence is that they are cheap and fairly easy to work on. Great for home kit builders who like to tinker with the engine in their hangar. However, in a flying school situation where L2's and LAME's are involved, costs can quickly get out of hand.

Jabiru valve $45 :ok:
Rotax 912 valve $280 :(

[Wally Mk2]

...............hey Tripple x tinkering with a piece of junk in yr hanger is fine, no one gets hurt but up in the air with that same piece of junk?............well tinkering is the last thing ya can do up there wishing you where down here still tinkering buddy:ok::ok:

'Forky' now that's funny, Jaba experience without having to be in one...........was it still 'safe'?:E


Wmk2

[Ultralights]

Jabiru valve $45
Rotax 912 valve $280

jabiru valve replaced every 200 hrs, $45x10 =$450
rotax valve replaced at TBO 2000 hrs. =$280 :E

actually when it comes to prices, i have heard a new 3300 is $19,000AUD
a new 912 ULS is $18,500 USD...

[VH-XXX]

Absolutely agree there Wal, just looking for a positive side if there is one.

Ultralights, problem is that the turbo Rotax at 115hp is in the mid $30k range and the J3300 is 19k for ~128hp ... and that is why people are still buying them.

[Jetjr]

912 vs 3300 ....... your 20 hp short in a 912
912 is an exceptional engine, no debate, but whats the relevance

At least compare 914 price, 2012 it was over $30K USD
Not convinced it has the same reliability reputation as 912

Your right Motz, the 15W50 is still in there, Seminar in 2012 saw this being strongly recommended to go back to W100+ from Jabiru and others.

[Ultralights]

from what i have heard, a J230 airframe with a 100Hp 912 performs equally as well as one with the Jab 3300 fitted. though i dont have any facts on hand, could possibly be just the advantage of a different prop. who knows, but the info i have heard is from pilots who have flown a 912 equipped J230/200 so for comparison of similar performance, the 912 would be equiv of the 3300. as said before, this is based just on hangar talk.

[VH-XXX]

The 912 100 hp is only any good for 600kgs if that.
Just hangar talk I'm afraid. There's a 912 J230 in NsW and performance is reported to be underwhelming. Happy to put anyone in touch with them if required.

[Jetjr]

At minimum would need IFA prop, need to add this to engine price and then not OK in RAA I believe

[VH-XXX]

Until recently IFA was only ok for a homebuilt RAA, but the regs have changed and IFA's are ok for LSA, just not reversible at this time. I know an LSA floatplane with IFA but they had to disable reverse as that's not covered under ATSM.


I priced up a 914 for a recent project. With a base price of ~$32-34k plus an IFA which is as good as mandatory for a turbo I was looking at around $40k plus custom engine mount plus rooting around fitting it.

I know it's not a turbo but a Jab3300 gets more 5-10 more horsepower for circa $17k with prop.

Fitting a new CAMIT 3300 to throw away at 800 you'd be looking at $20 an hour.

Running off a power by the hour concept, $20 is quite reasonable.

[Wally Mk2]

Hey triple x again yr dreaming there buddy more HP, cheap operating costs pale into insgnificance when it all stops mid flight, that's when you wish you had paid a few dollars more for peace of mind:ok:
Safety costs when it comes to a man in a plane/coffin & you could even get the cost almost down to zero using just a rubber band for power but what happens when the turns run out?:E By the sounds of things the Jabarubberband can't keep yr world turning 4ever:E

Wmk2

[VH-XXX]

Yep, what you are saying Wal goes without saying. Agreed.

[dubbleyew eight]

just when I was about to buy 2 jabiru engines mick had his shed a conrod and seize in flight.

scratch two purchases.

I am told that Jabiru engines are now made in china.
the appearance of the jabiru lookalike is an effort by the australian company that used to do the contract machining to make something of the disaster that they experienced when the contract ceased.

personally I wish jabiru well. but they have to get engines regularly making TBO before they will really get successful.
disasters dont have a great future in aviation.

[VH-XXX]

They aren't made in China.... yet. Some Chinese made components are in testing at the moment. The sump which is a major part of the engine in terms of cost, is actually cast by our Trans-Tasman neighbours in New Zealand.

All currently Australian made in Bundaberg in a custom built multi-million dollar cad/design shop.

[dubbleyew eight]

made in Bundaberg in a custom built multi-million dollar cad/design shop.

multi million dollar facility eh.
well that makes it all perfectly ok then. :mad:




the end product is still unreliable crap.

[Jack Ranga]

XXX works for Jabiru ;)

[VH-XXX]

Yeah that's right Jack. I work in their airconditioned Melbourne based satellite office :ok: We do all of their test flying out of the Melbourne CBD.

multi million dollar facility eh.

Just sayin'

W8 - just when I was about to buy 2 jabiru engines mick had his shed a conrod and seize in flight.


Your secret is out W8 :ok:

http://australianaviation.com.au/wp-content/uploads/2013/08/Twin-22-of-671-300x181.jpg

[Jack Ranga]

Turning it into a drone would be safer for the pilot community :ok:

[Sunfish]

I looked at a Jabiru 3300 for the project, but after reading of the horrific reliability issues and the stupidity of their cylinder head design, not to mention the voodoo necessary to cool them evenly and then of course their known carburettor issues (swirl vanes and flow straighteners anyone?) I gave them a big miss.

The UL power uncertified engines grew as a direct result of Jabirus head in the sand behaviour over helicopter engines.

The South African Jabiru fuel injection project grew as a direct result of Jabirus head in the sand behaviour over carburetion.

The liquid cooled heads project grew as a direct result of Jabirus head in the sand behaviour over cylinder head cooling and sealing.

Frankly, I want nothing to do with a company that isn't prepared to engage with its customer base, admit its fault and actively work with its customers to improve its product.


I now have a 912 iS sitting in its box, and I know that engine was tested in real life in Africa with crap fuel and a less than perfect operating environment and according to the people Im in contact with, it passed with flying colours.

[dubbleyew eight]

xxx you can wind away all you like.

one engine was for son's corby starlet and one was for an aeroengineer for a totally new design. design is now shelved until a reliable engine can be found.

[VH-XXX]

Just pushing ya buttons W8, I dind't really think you were building a Jabiru Twin.

Sunfish says - I now have a 912 iS sitting in its box

Sorry for the drift and I'm sure I'll get accused of Rotax bashing, however that's actually quite amusing because Rotax are having significant problems with this engine at present. If you read Rotax's own publications they only produced a fuel injected version to please their customers who kept on telling them to get with the times and fit fuel injection. Experts have suggested that they released it to market too quickly.

There's one in Tassie that regularly flies to Vic or at least it used to until it spent months in a hangar at LTV whilst parts were continually shipped back and forth from Germany. Problems with the injection system. All the experts were at a loss to work out what went wrong and when it was "fixed" it burped and farted the second half of the trip to Tassie again. I have also heard numerous other reports of issues, but on the other hand have also heard a number of good stories.

I would be fairly confident that they will resolve them however if it's been sitting on your floor for a while Sunfish, you may want to talk to Floods about whether the early issues have been addressed.

[Jetjr]

yes, said before, 912 is exceptionally good engine, not sure variants can say the same yet
Some upset 912iS owners around the world
variable engine performance, poor starting. I too believe they will sort it out but like anything man made will take some time to get there.
Reckon Jabiru might have smaller R&D budget than Bombardier and they still have product development issues with a product they have included on other models for 10 yrs or more.

[Jetjr]

Jab powered drones running around Middle east I believe

[Ultralights]

I work in their airconditioned Melbourne based satellite office We do all of their test flying out of the Melbourne CBD.
ahhh so that explains the Jabiru excuse that some are operating them in the incorrect weather zones in Australia leading to some failures...

There's one in Tassie that regularly flies to Vic or at least it used to until it spent months in a hangar at LTV whilst parts were continually shipped back and forth from Germany. Problems with the injection system. All the experts were at a loss to work out what went wrong and when it was "fixed" it burped and farted the second half of the trip to Tassie again. I have also heard numerous other reports of issues, but on the other hand have also heard a number of good stories.

I would be fairly confident that they will resolve them

At least Rotax are actively working to resolve the problems with operators, unlike Jab who just seam to keep blaming the operators, and hiding away all failed components and not finding out what causes the issues..

and from what i have been reading, the issues with the 912Is most of the issues are computer and sensor related, the mechanicals of the engine are sound as always. its not going the throw a rod, snap a through bolt, drop a valve etc. a 912IS would make a great replacement for my 912ULS when its reaches TBO. would give me an 8 hour endurance!

[Jetjr]

failed ECU sure can mean all those things
Anyway whatever the problem no noise = landing

[Lsw1941]

My 2011 J230SP LSA has 435 hours on it with no engine trouble. I almost always cruise at 2850-2900 rpm's.

The first thing my mechanic did when I bought the plane (new) was re-baffle the engine which resulted in an average reduction in CHT's of 65 degrees farenheit. The factory baffling is inferior which results in higher operating temperatures than are necessary.

If my choice was to correct the baffling and risk the factory's ire or live with the inferior factory baffling and replace the engine, I'd opt for the former.

And BTW, has anyone had the pleasure of an engine out in flight due to improper venting of the fuel tanks from the factory? I did, twice, and there's a simple fix to prevent it.

[smokeybear]

Two UK engine failures

Engine 1 had 43 hours total since new
Engine 2 had 49 hours total since new



"Three cylinders and their associated pistons were taken to the Materials Department at QinetiQ (Farnborough) for detailed metallurgical examination. Examination of the three cylinders showed that No 3 piston and cylinder exhibited characteristics similar to the No 3 piston and cylinder from G-CEED. The piston/cylinder head interface exhibited sooting on one side of the cylinder, with the corresponding edge of the piston exhibiting burn-through (Figure 2). The internal surface of the cylinder showed evidence of minor wear and material pick-up from the piston at the point of the piston burn‑through. Skirt wear was observed on the piston similar to that observed in the examination of the engine from G-CEED. Minor wear was observed below the burn-through with the opposite skirt exhibiting more severe wear. The other two pistons both exhibited skirt wear similar to the No 3 piston. One of the pistons showed evidence of damage to the edge of the piston crown with reciprocating wear and material pick-up on the internal surface of the cylinder. The damage appeared to be purely mechanical, with no evidence of burn-through as seen in the No 3 piston.
Examination of the piston rings and oil scraper rings showed that the lower piston ring was seized in the closed position on one of the pistons and on another the upper ring was seized at the area of the damage, so that it was flush with the piston edge. The other end of the piston ring was free to move. On the No 3 piston both the lower piston ring and oil scraper ring were seized in the closed position."

Google this title (not a link) for full pdf report with pics
https://assets.digital.cabinet-office.gov.uk/.../Savannah_Jabiru__G-CEED.

Another excerpt from the report

Carburettor mounting effect on cylinder head temperature

A UK CAA-Licensed Aircraft Maintenance Engineer, and owner of a Jabiru-engined aircraft, conducted tests with differing angles of mounting the carburettor to the plenum chamber, and at the same time monitoring cylinder head temperatures (CHT) and exhaust gas temperatures (EGT). He found that by tilting the carburettor 10° to 15° left and right he could obtain a rise and fall in CHTs between Nos 1 & 3 cylinders and Nos 2 & 4 of up to 50°C and EGTs up to 120°C."

[Ultralights]

so, its more than 12 months now, how are those 912IS's going? good it seams.. ECU and sensor issues sorted. all is good with the world again... amazing what a bit of customer service and feedback achieves...

now, the new 135Hp Rotax in a J230 airframe will be a top seller, indestructible well performing aircraft.. not to mention a decent service ceiling to boot with 100% power available up to 15,000 ft.

[no_one]

Putting a rotax 915 in a jabiru J230 would be serious over capitalization.....

[criticalmass]

I suspect the installed-weight of any of the Rotax 912-family engines in a Jabiru airframe requires significant compromises in either fuel or crew-weights.

I've heard of Rotax installations in Jabiru airframes. I have actually met someone who claims to have flown one. I have seen a photograph of a J160 purporting to have Rotax 912 installed in it...but I have never actually seen one of these aeroplanes, nor have I seen any review of the performance (or possible lack of it), or the pros and cons of the installation, etc etc etc. Additionally, it is only an option (if it is viable) for home-builders.

Putting any Rotax engine into a Jabiru airframe isn't a simple task. Attractive? Yes. Simple? No.

[Squawk7700]

I suspect the installed-weight of any of the Rotax 912-family engines in a Jabiru airframe requires significant compromises in either fuel or crew-weights.

I've heard of Rotax installations in Jabiru airframes. I have actually met someone who claims to have flown one. I have seen a photograph of a J160 purporting to have Rotax 912 installed in it...but I have never actually seen one of these aeroplanes, nor have I seen any review of the performance (or possible lack of it), or the pros and cons of the installation, etc etc etc. Additionally, it is only an option (if it is viable) for home-builders.

Putting any Rotax engine into a Jabiru airframe isn't a simple task. Attractive? Yes. Simple? No.

I know of at least three and have been for a ride in one of them. All of the owners are super happy with the combination, one of them over the moon about it.

[Squawk7700]

Putting a rotax 915 in a jabiru J230 would be serious over capitalization.....



Well not really... A J230/430 is roughly an $80k airframe new from the factory and just guessing the engine will push $40k.

How many old C172's or Cherokees are over capitalised?

[no_one]

I doubt that the new rotax 915 will be $40k. The 914 is 28k US and the new 915 will be at least $5k more. add shipping, GST and convert to aussie and you will be north of 50k.

Add a prop to deal with the new power, the cost to install it all and you will endup with a very expensive aircraft. A 912s on the other hand makes some sense.

[Squawk7700]

I doubt that the new rotax 915 will be $40k. The 914 is 28k US and the new 915 will be at least $5k more. add shipping, GST and convert to aussie and you will be north of 50k.

Add a prop to deal with the new power, the cost to install it all and you will endup with a very expensive aircraft. A 912s on the other hand makes some sense.

Unfortunately the 912s is a little underpowered for the J430 which limits options to the Camit at circa 130 hp, the 914, 915 or something else...

http://www.aircraftkits.com.au/jabiru_conversion.html

Should be adequate for the J230@600kg however.

The 915 and CSU prop are a ridiculous amount of money for any aircraft. They make the Lycomings look cheap as chips.

[outlandishoutlanding]

I've heard of Rotax installations in Jabiru airframes. I have actually met someone who claims to have flown one. I have seen a photograph of a J160 purporting to have Rotax 912 installed in it...but I have never actually seen one of these aeroplanes, nor have I seen any review of the performance (or possible lack of it), or the pros and cons of the installation, etc etc etc. Additionally, it is only an option (if it is viable) for home-builders.


In 2011 I took a lesson (out to the coast, and a couple of circuits at YWVA) in a 24-registered (ie "factory-built") J160 with a 100hp rotax in it. It was a very pleasant plane to fly (but note that this was only the third type I had ever flown). Performance was very acceptable, and definitely better than the J160s with the Jabiru 2200c. I don't remember any strong nose down tendencies.

Mind you, this was a single hour lesson 4 years ago so my memories might not be completely unbiased. My memories of it are definitely better than my current experience of J160s (underpowered).

[Sam Rutherford]

Two engine failures in one flight, the second one to the ground (airfield)

So,

I had an interesting day with a 'new' plane (microlight) - and am trying to figure out what might have happened. Help appreciated.

I'll bullet point the bits I think important...

• Avid Flyer 4, in great condition.
• Jabiru 2200, in great condition.
• Flight across Alps, south to north.
• Average altitude 9000’, maximum 12K.
• 4 hours.

Took off as normal, but only after a weird whistling on the comms – stopped by removing the aircraft power supply and relying on the 9v battery inside.
After 3 hours, engine started running roughly, occasionally. Carb icing suspected but carb heat had no effect.

Suspected choked/choking mags (no leaning option on this one) – so attempted to lean with fuel tap. Fairly difficult – several donkey stops before I found the point on the tap (only 90 degrees between open and closed!) – but again, no real change/improvement.

Problem increasing – so I increased RPM (from 2600 to 3000) and engine ran faster than for a normal cruise but smoothly, EGT etc. all okay.
Then, silence. Long let down to valley floor (doing all the usual things) engine restarted (by itself) at about 500’ agl – I’d have made my field I think…

Nearest airfield 10 minutes away (long 10 minutes!), engine running smoothly. Made a very tight circuit and once on base reduced power – engine cut. Landing made. Tried to start engine immediately, but barely turned over then clicking from starter (typical weak battery noise). Pushed plane to taxiway and apron…

Closer analysis with a multimeter, battery reading 12.1V and once engine started with external power there was no change to this figure with RPM movement. The aircraft has no electrical system indicators.
30 years flying, and I get two engine failures in one flight!

Answers on a postcard?

Fly safe, Sam.

[Stanwell]

A bit of the 'pucker factor' in that experience, was there, Sam?
Not being a techie, I'm not able to contribute but I'll watch this one with interest.
Good to hear it ended without tears.

[Sunfish]

I love a good mystery!

"whistling" = AC voltage from failed or partially failed alternator rectifier? little or no battery charging?

gradually weakening battery voltage reduces sparks at plugs?

After shutdown, battery has enough time for recovery just enough to give you sparks again at 500'?

Why not at least an ammeter light?

Alternative: failing ignition module?

[rutan around]

Suspected choked/choking mags

Sam please send a photo of the mags as installed.

[Squawk7700]

Hi Sam,

A few notes for you...


Carb icing suspected but carb heat had no effect.

Make sure you leave it on for a while and don't just pull on and then off fairly quickly.

Suspected choked/choking mags (no leaning option on this one)

The Jabiru engine has dual ignition coils. It does not have traditional magnetos. As the magnets on the flywheel pass the coils, a spark is generated. In theory no battery power is required, however the battery is required (a flat battery is ok) to complete the circuit. When you talk of "choking the mags" you are talking of fouling spark plugs. Indeed this is possible (whilst fairly unlikely) with the Jabiru / bing carby configuration, particularly at high altitude as the bing carby is not altitide compensating. It allegedly is to an extent but practical experience says otherwise. Who knows how your needle and main jet are configured... potentially it's set as rich as hell and you were very rich up top which should show up with rough running. If that's the case, you'll be so rich that you'll be washing your cylinders with fuel and causing excess wear to your rings and cylinders.

so attempted to lean with fuel tap. Fairly difficult – several donkey stops before I found the point on the tap (only 90 degrees between open and closed!) – but again, no real change/improvement.

You could be safely assured that this is not a great idea. What you're doing is running the carby bowl out of fuel and then drip feeding from the tap. If you believe you had a flat battery you'd be in strife if the engine stopped on you!

Problem increasing – so I increased RPM (from 2600 to 3000) and engine ran faster than for a normal cruise but smoothly, EGT etc. all okay.
Then, silence. Long let down to valley floor (doing all the usual things) engine restarted (by itself) at about 500’ agl – I’d have made my field I think…

How did the engine start by itself, was it turning over during the descent? Sure, if it turns over fast enough 280rpm approx, it will indeed start if the ignitions are on.


Closer analysis with a multimeter, battery reading 12.1V and once engine started with external power there was no change to this figure with RPM movement. The aircraft has no electrical system indicators.
30 years flying, and I get two engine failures in one flight!

Sounds like your stator isn't working and you simply aren't getting charge. It's pretty common for the two wires that come out of the stator to touch and short out as the plastic covers on the spade terminals are a very soft clear plastic and they rub and melt through. Either that or you have a wiring issue elsewhere. Check the wires running from the stator to the regulator. The light blue 16 gauge wires are the ones that are connected to the stator.

Consider fitting an AMPS meter or a volts meter as a minimum. There are plenty on EBay, in fact some simply plug into a cigarette lighter socket - can't get much easier than that.

If you are regularly going to fly at high altitudes and you already have EGT gauges, I recommend fitting a Hacman mixture controller. It's a needle valve on the dash with a couple of plastic hoses - one is tapped into the carby vent line and the other to the vacuum under the carby. You will then be able to lean your mixture at higher altitudes which will not only keep the EGT's the same as sea level, but also reduce fuel consumption and premature wear (as above). I have one and it works brilliantly. Very easy to fit and if you buy their version perhaps around $200. You could do it yourself by using hose and a dentist style needle valve with tap - all available from Ebay.

[Sunfish]

so jabs have mag coils, does this exonerate the battery?

[rutan around]

The Jabiru engine has dual ignition coils. It does not have traditional magnetos. As the magnets on the flywheel pass the coils, a spark is generated. In theory no battery power is required, however the battery is required (a flat battery is ok) to complete the circuit.First part is correct. Second part is not unless this particular aircraft has a non Jabiru wiring arrangement. On a standard Jabiru the battery can fall out of the plane and the engine will run normally till the fuel runs out.http://cdn.pprune.org/images/smilies/boohoo.gif

As this aircraft is not a Jabiru (only it's engine) a few questions come to mind:-

Why cruise at 2,600 RPM when Jabiru recommends 2,850 - 2,950 RPM ? Jabiru does not recommend cruising at 2,600 revs You can run it at higher than 2,950 revs but it will chew fuel.

Does the aircraft cruise fast enough to provide adequate cooling?

Are cooling tubes installed to direct cool air onto the ignition coils as called out in Jabiru aircraft? If you don't have them the coils can overheat and run intermittently.

When you went to 3,000 revs did you return the fuel tap to full flow? If you didn't the fuel flow wouldn't have been enough to keep the engine going.

[Squawk7700]

First part is correct. Second part is not unless this particular aircraft has a non Jabiru wiring arrangement. On a standard Jabiru the battery can fall out of the plane and the engine will run normally till the fuel runs out.

Correct you are. I didn't go into too much detail as you generally need the battery to start it :-)

I had discounted the coils breaking down because they generally don't go U/S at the same time. I find with dodgey ones that they start to run rough about 5 minutes after takeoff (and over a certain RPM - around 2,800+ usually) and even though they are redundant, you can still notice things aren't going well when one of them is misbehaving.

The issue described smells like the stator but I'm at a loss to know why it would have stopped the engine. Doesn't sound like fuel, but does sound a little like coils, but being redundant... not sure.

[rutan around]

Warning. Thread drift but still relevant.
Over the last 12 months for various reasons there has been dramatic increase in compliance to the Service bulletins/ Letters and maintenance procedures issued by Jabiru This combined with Jabiru engine training workshops has resulted in fewer incidents and has put Jabiru engines well ahead of Rotax for reliability, the standard by which CASA based their aggressive actions.

[Ultralights]

does anyone have numbers for the Jab fleet in the last 2 years?

[Jetjr]

Majority of engines with problems were in flight training........all maintained by L2 or LAME
Self maintained others saw very few problems. Older versions even less

I heard 7000 engines, 2000 Jab airframes

[Aussie Bob]

Majority of engines with problems were in flight training........all maintained by L2 or LAME Self maintained others saw very few problems. Older versions even lessJetjr, I think you have this backwards. Flying training has a far better record than owner maintained. The private self maintained ones I have seen seldom do 500 hours between major work. The ones in the flying school I worked for regularly reached 1000 hours untouched and were returned to the factory for an exchange in lieu of doing a top end overhaul. Ditto for other flying schools that I know that operate Jabs

Using a Jab engine daily seems to be good for reliability. Ones that sit in hangers for weeks or months at a time don't seem to last many hours. Outdoor storage with infrequent use is a recipe for early failure.

[zac21]

(Over the last 12 months for various reasons there has been dramatic increase in compliance to the Service bulletins/ Letters and maintenance procedures issued by Jabiru This combined with Jabiru engine training workshops has resulted in fewer incidents and has put Jabiru engines well ahead of Rotax for reliability, the standard by which CASA based their aggressive actions.)

Surely you jest (If your comparing 912/914 4 stroke and not two stroke)
Absolutely no comparison,, the Rotax beats them hands down no question.

[Squawk7700]

Hi Zac, can you please provide a link or cite the evidence that suggests that Rotax are "hands down no question" are more reliable than Jabiru engines?

Thanks.

[Ultralights]

i think the ATSB has some data on engine failures by type per 100,000 flight hours.

[Squawk7700]

That's the data that is a problem... it's the skewed data that CASA used to put limitations on Jabiru engines that included fuel exhaustion and other non-engine related stoppages.

The blue text above has been quoted from Jabiru directly in an email that went out to operators. They have been working closely with CASA and the ATSB to go analyse the information and to carefully monitor each and every failure and document it, including since the release of said data. The result of this has been a more accurate set of statistics that I believe based on what I've heard from higher sources will prove what is written above.

At a guess, we are not likely to see an update of these statistics any time soon, just through regular reporting.

[Jetjr]

No Bob its from Jabiru/casa/atsb themselves and is built into most recent head inspection SB
Majority of engine failures were in flight training aircraft, mostly 4 cyl and almost all hydraulic lfter type

The link with poor maintenece is misleading. This problem is that concept forms the basis of keeping restrictions on experimental and modified aircraft. They have to "upgrade" to latest spec to hve them remove I think

[zac21]

S7700,,
2200 hours training and mustering in a 912 trouble free while I watched the Jabber's fail one after another with very low hours. But I won't fly a 2 stroke either !!

[youngmic]

On a standard Jabiru the battery can fall out of the plane and the engine will run normally till the fuel runs out.

.....or it drops a valve, frees a valve seat, overheats or has a bottom end through bolt related failure, which ever comes first.

Fixed :ok:

[rutan around]

....or it drops a valve, frees a valve seat, overheats or has a bottom end through bolt related failure, which ever comes first.

Fixed http://cdn.pprune.org/images/smilies/thumbs.gifExactly as you say Young Mic 'Fixed' It is a great credit to the Jabiru Company that as their engines evolved they actually addressed any problems that were found. As solutions were found notifications were sent out to owners detailing what needed to be done to ensure the engines performed safely. Sometimes these notices were to replace parts and sometimes they were operational and maintenance issues.

Jabiru's major problem was that many owners chose to ignore the notifications.

The truth of this was spelled out when RAA/CASA (I think it was) came up with the idea that the aircraft's engine maintenance log had to be sent in with the annual licence fee. Of the first 70 or so sent in only 3 engines fully complied with the factory service bulletins, maintenance schedules and maintenance procedures.
The great improvement in reliability has come about because the licence renewal is withheld until the engine is compliant.
Most owners are not engineers and they don't fully grasp the complexities in designing a completely new engine. Even giant companies have teething problems with new equipment. Airbus 380 and Boeing 787 come to mind.

I realize it was just a throwaway line but I wonder if Young Mic understands the real reason the through bolts were failing and what the factory had to do to identify the cause. (If you don't understand the cause of a problem anything you do to fix it is just a guess)

Two things to note. I am not an engineer and I don't own a Jabiru plane or engine. I've always had an interest in engineering and I think Jabiru should be given a fair go as they appear to be a company doing the right thing by their customers which is more than can be said about Continental and Lycoming. http://cdn.pprune.org/images/icons/icon8.gif

[Sunfish]

I just had my Rotax 912 iS alternator stator replaced with an upgraded version (Thicker wires for alternator B). Total cost zero. Does Jabiru run a recall and upgrade program or is it all at owners expense?

[youngmic]

Rutan Around

It is a great credit to the Jabiru Company that as their engines evolved they actually addressed any problems that were found.

An interesting spin.

My casual understanding of the matter is the exact opposite of what you have stated, I believe many would agree with me.

Numerous cases of Jabiru engines failing not long out of factory O/H and just to really tick the customer off and add insult to injury they follow up with often pretty poor support.

Was it not the case that CAMit (the original Jabiru engine builder) had been pushing Jabiru for some time to incorporate their mods to solve some of the inherent engine issues. I understood they were ignored time and time again. Now they are marketing the Jab engine under their own name with the necessary mods and doing very well as I understand.

Whilst all this was going on CASA stirred from its slumber, rubbed its collective eyes, looked at what was going on, called a meeting or 2, weren't satisfied so slapped a heap of operating restrictions on Jabirus.

Now a blind man on a galloping horse could see what will happen next....100's of Jabiru owners just had their asset devalued.

Hardly a company deserving of great credit at the moment.

I have been watching the development of the 3300 for some time as that engine might be a great replacement for my O-200 but sadly it just isn't getting the run tally up.

I'm not sure what iteration of Burt's you own but you would be a braver man than I to take flight with 2200/3300 bolted to the back.

[Ultralights]

The truth of this was spelled out when RAA/CASA (I think it was) came up with the idea that the aircraft's engine maintenance log had to be sent in with the annual licence fee. Of the first 70 or so sent in only 3 engines fully complied with the factory service bulletins, maintenance schedules and maintenance procedures.

By that logic, then every Rotax engine owner is keeping on top of, and is well trained in maintenance of their engines? just Jabiru owners who dont care for maintenance.

[rutan around]

By that logic, then every Rotax engine owner is keeping on top of, and is well trained in maintenance of their engines? just Jabiru owners who dont care for maintenance. I really can't comment on the accuracy or otherwise of your thoughts without reliable data.
All I know is that since proper servicing and maintenance has been virtually forced on owners there has been a rash of reliability to the extent Jabiru's recent record is now better than Rotax's.


I realize it was just a throwaway line but I wonder if Young Mic understands the real reason the through bolts were failingWell Mic???
PS. In the earlier pages I didn't know either thus the long bow theories back then.

[youngmic]

Well Mic???


I don't normally jump through hoops for little reason but I'll make an exception, I am not sure what the purpose of the question was but I pulled up the Jabiru SB and below is what it says. All sounds pretty normal to me with an insufficiently strong through bolt suffering metal fatigue likely due to cyclic loads to close to its yield point.

But what's your point?

3.2 Contributing Factors 

A number of factors can contribute to through-bolt failure. The following list contains a few examples but there are many other, smaller, factors which can have an impact.

a) Detonation or uneven combustion. Detonation or uneven combustion can be caused by incorrect tuning, induction system leaks, stale or incorrect fuel or a number of other factors. The result is increased engine vibration.

b) Operation. Engines which work hard with high engine temperatures tend to have more issues than others.

c) Maintenance. In some cases through bolt failures have been caused when a person has tightened them beyond the design tension. Poorly calibrated torque wrenches and poor understanding of tools like the “crowsfoot” torque wrench extension also contribute.

[Sunfish]

Contributing factors? My ass! The additional metal to ensure there are no such failures at all, under basic maintenance, is insignificant. Begging the question of alloy selection, heat treatment, surface modification (shot peen,, etc), let alone using "waisted" bolt designs.

Stuff like through bolts should not fail EVER! ..under responsible maintenance anyway.

this is a pet peeve of mine, I know weight costs $100 per pound, arbitrarily anyway, but it annoys me when designs fail at multiple points for want of an extra 20 grams of steel, alloy or carbon in the right place.

Then of course there is the F27 landing gear story of how cracking failures were eliminated by removing metal.

[Jetjr]

For clarity, there is no requirement to submit maint logs to RAA, it was an audit done randomly which found poor log book compliance. Very few even replied, dont think it was anything to do with Jabiru but checking the service records of all makes.
It is relevant however as without accurate records, little should be drawn from data like casa used to make their limitations

Jabiru have always claimed problems are servicing related, now they have regulatory backing to force owners to upgrade to latest iteration of their engine.

[Squawk7700]

I just had my Rotax 912 iS alternator stator replaced with an upgraded version (Thicker wires for alternator B). Total cost zero. Does Jabiru run a recall and upgrade program or is it all at owners expense?

You have a lot to learn young grasshopper Sunfish.

Did you hear about the 912 recall that meant that owners were up for up to half of $12k for a new crank case because their engines were of a particular serial number range? The operator I know of got away with $6,000 on his half life engine as Rotax funded half of it.

How much will a rebuild cost on your $26k? engine Sunfish, perhaps around $23k?!?! Jab used to rebuild engines for $6.5k for flying schools.

[rutan around]

Youngmic asked
But what's your point? Mic I'm sorry if I caused you to jump through hoops but the question was posed to 'start the conversation' ( in pollie speak). I also apologise for my tardy reply . This working till we're 70 is the pits. WORK- the curse of the drinking class.http://cdn.pprune.org/images/smilies/boohoo.gif

You quoted valid possibilities from the Jabiru Service Bulletin and Sunny mentioned shortfalls in alloy and steel strengths. I'd heard all of these reasons in various pilot BS sessions and generally in more colourful language about Jabiru.

I couldn't understand why the bolts were breaking. They should have been plenty strong enough given that 3/8 bolts will yield at 2.5 to 5 tons. Nor could I believe that in this day and age Jabiru would choose some inferior alloy for their engines. Detonation, severe operation and over torquing didn't explain it either as the bolt problem was fairly widespread and those scenarios aren't all that common.
I never did guess the real problem. I recently found out while visiting Bundaberg and got talking to people involved with solving the mystery.

It was that old nemesis of aviation - harmonics. The natural frequency of the long 3/8 through bolts was found to be excited at certain high power settings.
Once excited, the bolt makes like a sine wave vibrating the bolt and of course the ends with the nuts. Eventually the vibrating nuts & washers chew into the alloy they're up against and the bolt becomes loose. Mr pilot tightens the nuts and tells anyone who will listen that the alloy is s#*t. With enough repeats of the above the bolt would break. Then Mr Pilot tells everyone the bolts are weak.
Harmonics, flutter, divergent resonance are part of the dark arts in engineering engines. It's a science in itself and is complicated. Even now some GA engines have no go rev ranges. A Grumman I flew had (from memory ) 2,000 - 2,250 no cruise area. Many normally aspirated Continentals have a recommendation to not cruise below 2,300 rpm.

Back to Jabiru. The bolt only resonated at high power settings. Hence Flying Schools going to full power more often, or a bigger % of their flight time, were more likely to experience failure at lower hours than the rest of the fleet.

The cure is to install the 7/16 bolts which don't flutter in the rev and load range ever likely to be seen by a Jabiru.

[youngmic]

It was that old nemesis of aviation - harmonics. The natural frequency of the long 3/8 through bolts was found to be excited at certain high power settings.

Fair enough.

[AbsoluteFokker]

FYI, Grumman Tigers are not allowed to be descended at 1850 and 2250 RPM due to engine/prop harmonics. This was only an issue in the standard McCauley props. Sensenich probs did not have that issue. Later Tigers used the Sensenich props as factory stock.

[Aussie Bob]

Interesting about the harmonics .... It would appear that Jabiru, like other aero engine builders in modern times has used the end customer as the R & D dept.

[rutan around]

. It would appear though that Jabiru, more than any other company in modern times has used the end customer as the R & D dept. Fair go Bob. What about Lycomings little frolic in metallurgy when they altered the metal alloy used in their crankshafts to make them easier to machine with c&c machines. That killed quite a few people and cost our industry millions.

Then there was Continentals effort to reduce oil consumption by increasing the ring pressure against the cylinder walls. That experiment virtually stopped oil consumption but wore the cylinders out in about 400 hours. Yes you guessed it. Just out of warranty. Another R&D exercise that cost owners millions.

Neither Lycoming nor Continental came out of that smelling of roses. Their efforts to avoid rectification were disgraceful.
Both events occurred within the last 20 years.

[rutan around]

I nearly forgot. What about Continentals ongoing experiment with little or no Quality Assurance when case hardening their cam lobes and followers.

That coupled with their hit and miss method of seating valves in their new and overhauled io520s and perhaps other models is trashing the company's name.

CASA is asleep at the wheel and some LAMES/ engine reconditioners aren't bothering to report such incidents because past experience has told them they're wasting their time and energy.:ugh:

[Aussie Bob]

Thanks Rutan for the reality check, post above edited ....

[JabiruGliderPilot]

Hi X. ATSB research sums it up well in their massive research project into engine failures "ar-2013-107". ".......Aircraft powered by Jabiru engines were involved in the most engine failures or malfunctions with 130 reported over the 6 years. This represents about one in ten aircraft powered by Jabiru engines in the study set having reported an engine failure or malfunction. Reports from Rotax powered aircraft were the next most common with 87 (one in 36), followed by aircraft with Lycoming (58 – one in 35) and Continental (28 – one in 35) engines. When factoring in the hours flown for each of these engine manufacturers, aircraft with Jabiru engines had more than double the rate of engine failure or malfunction than any other of the manufacturers...."

[Squawk7700]

Lol nice thread dredge.

It was determined after that report was released that those Jabiru failures even include fuel exhaustion caused by the pilot. The numbers were not accurate in any way, shape or form and the restrictions placed on them were lifted. It even made it all the way to the senate committee.

It even included an issue that I had personally flying a Jabiru where a piece of cheap prop tape fell off in the rain and caused a vibration... hardly an engine malfunction!!!

[mcoates]

You must also remember, The Rotax numbers also included the two-stroke engines.

This is why it was impossible to compare apples with oranges, nothing was counted correctly right from the very start.