CASA - Draft Proposal for Jabiru Aircraft

[dodo]

I think anyone with a Jab engine or an interest in the process has left or is leaving this Rotax thread

 

 

[dazza 38]

I think anyone with a Jab engine or an interest in the process has left or is leaving this Rotax thread

Why ? It is CASA that is comparing Jabiru's failure rate with the Rotax. Facts are. The Rotax is a lot more expensive to purchase and the parts are expensive. Having said that, the Jabiru is cheaper to buy and parts are cheaper but the Jab engine needs a lot more tender loving care in both operation and maintenance. It is natural for both engines to be compared to each other because they together dominate the LSA market with

Rotax flying the most hours with less failures.

 

 

[dodo]

I give up.

 

 

[Guest Ornis]

Question. A 3300 sold today, does it have solid lifters? YES/NO

 

 

[Geoff13]

And the reason that Camit go for solid lifter is?.......

 

 

[Guest Ornis]

So, still persevering with hydraulic lifters.

 

I noted trawling through the Jabiru site the flywheel bolts are to be replaced every 100 hours. More nonsense.

 

 

[skeptic36]

It didn't give me a stiffy.

Don't tell us your problems......

 

 

[jetjr]

I noted trawling through the Jabiru site the flywheel bolts are to be replaced every 100 hours. More nonsense.

Only if runnng non approved prop

 

Current SB basically says if you want to run outside parameters or in training type applications you need to implement extra inspections

 

New engines from Jabiru have roller hydraulic lifters

 

Camit have stuck to solid lifters because majority of the reliability issues came with hydraulic upgrade. They have started upgrades on a known solid base.

 

You can buy solid lifter engine rebuilds and upgrades from Jabiru if you ask

 

Merv, as has been said many times, there are new through bolts in larger diameter, back when you had problems it was a longer bolt the same size. camit have a totally different through bolt and cylinder base

 

 

[dazza 38]

If Jabiru wants to move forward, they would better off going back to a solid lifter engine, as mentioned by multiple people. They just have to listen.

 

 

[kgwilson]

If Jabiru wants to move forward, they would better off going back to a solid lifter engine, as mentioned by multiple people. They just have to listen.

I know that Ian Bent has done this with his engine but Jabiru have modified the hydraulic lifter engine with roller followers. Are there any reports of problems with this configuration? It hasn't been around for that long but there was a lot of pre-release testing & I haven't heard of any issues to date.

 

 

[Geoff13]

Yes Ian has done that with his engine (gone back to solid lifters) but can anyone tell me why?

 

 

[Old Koreelah]

If Jabiru wants to move forward, they would better off going back to a solid lifter engine, as mentioned by multiple people. They just have to listen.

I believe several aero engines have hydraulic lifters, including Rotax. Surely Jabiru can get theirs running reliably.

 

 

[dazza 38]

I believe several aero engines have hydraulic lifters, including Rotax. Surely Jabiru can get theirs running reliably.

True but Jabiru seem to have problems for some reason.

 

 

[jetjr]

I think maybe lots of people warned Jabiru against going to hydraulic lifters, Ian may have been against it from the beginning, even some internal people were against them and promoted solid lifters.

 

For CAE version, Ian began where his last R&D work finished

 

Hydraulic lifters rely on many other systems working as they should, oil system being key. They are just "automatic lash adjusting lifters" so a huge amount of pain for not much gained. Adjusting tappets isnt hard and if the run cool rarely need adjustment

 

Imagine if al the effort spent on redesignong engine to get them working was spent on head and valve design or fuel distribution, what about investigating crank vibrations and flywheel problems.

 

Question being what have hydraulic lifters achieved except lower reliability?

 

Dont Really care what Rotax do its a totally different engine, furher developed but lower in HP

 

 

[Guest Andys@coffs]

Yes Ian has done that with his engine (gone back to solid lifters) but can anyone tell me why?

Because in the beginning Jabiru engines were solid lifters and the problem was that Jabiru believed that owners were having trouble setting tappets clearances......Not the most stressful job you'll ever face.....

 

The last of the solid lifter engines had a reputation of being generally reliable(ish), but easy to overheat by virtue of the thick finned heads that were later replaced by thinner and more fine finned heads. Also the cooling shrouds back then didn't have middle baffles for Cyl's 2 and 5 on the six. If the shrouds were replaced, the engine oil cooler updated to the latest (original was a bit small) and the exit lip on the lower cowl increased (while the cuttout size was also increased to have larger volume ) to exhaust more air then cooling could, with the installation of 6CHT and 6EGT probes be controlled. Im not aware of any through bolts breaking on any solid lifter motor. Anyone know of any? J made us change the bloody through bolts anyway.....but I suspect it was an overkill for those motors

 

Andy

 

 

[motzartmerv]

Merv, as has been said many times, there are new through bolts in larger diameter, back when you had problems it was a longer bolt the same size. camit have a totally different through bolt and cylinder base

Back when? One month ago was our last thru bolt failure. ;) but hey, let's not let this 'data' influence anything

Latest spec bolts. Installed by the factory.

 

Yawwnnn!!

 

 

[Geoff13]

Solid lifter engines have been breaking thru-bolts long before hydraulic came along, I'm afraid. I recall a CFI in Southern Aust telling me he had popped the odd one but was usually able to limp home.

In fact this fits in perfectly with my understanding of why solid lifters are better than hydraulic lifters in the case of Jabiru engines.

 

It has little to do with when or if they will break through bolts and a lot more to do with the early detection of a possible problem in the making.

 

With the solid lifter detecting regular changes in the valve lash setting prewarns of movement/streching of the through bolts and as such prewarns of potential failure rather than actually stopping the potential failure. This is a fairly simplistic explanation as I understand it. It may not be correct nor may it be the total reason for one over the other.

 

This also fits in with Andy's earlier explanation, that Jab thought people were unable to adjust tappet clearances which as he said is not the most difficult thing in the world to do. The tappets being poorly adjusted could have been a symptom rather than a cause. This also seems to fit in with the philosophy of looking for someone else to blame rather than looking for the real problem.

 

Cheers Geoff13

 

 

[Guest Ornis]

There is more to cooling the engine than a few deflectors. If anyone wasn't detailed information to lower from 160 to 120-130 or even perhaps 200 to 120 if things are that bad, just ask me.

Thanks, I would like information on how to maximise cooling. (I don't know how to private-message.)

 

Split the case of a year-2002 3300 (8:1) around 1100 hours, no sign whatever of crankcase fretting. The original through-bolts had been reused around 800 hours.

 

Through-bolts breaking. If the flywheel bolt fiasco is anything to go by, the reason is movement, insufficient clamp, bolts not being stretched properly.

 

 

[rankamateur]

(I don't know how to private-message.)

Click on "deborahlwayman" in the avatar above.

 

Click on start conversation.

 

Type subject line.

 

type message.

 

reply will appear at the envelope icon next to alerts above right.

 

 

[jetjr]

Seeing as throughbolts breaking on solids, the one you mention is the only one known and happened "regularly"

 

Maybe there was something wrong like the lean burn kit recommended at the time

 

Still think detonation is a cause.

 

So Merv which bolts did it have? "latest " doesnt cut it

 

Jab say no new throughbolts have failed. Silly claim if theres a knocker like you out there with one.

 

A good thing in the latest SB is the fitment of EMS is promoted.

 

 

[dlegg]

There is more to cooling the engine than a few deflectors. If anyone wasn't detailed information to lower from 160 to 120-130 or even perhaps 200 to 120 if things are that bad, just ask me.

Any details you can share here I'm sure will be warmly received. Mine runs on average 150 at cruise but would like to see if lower is possible.

 

 

[Russ]

 

This works a treat, I can maintain full power indefinitely, Max's to mid green, cruise sets at the bottom green. I've got the numbers somewhere.

 

Full power, 250f = 121c

 

Cruise........205f = 96c

 

That's reading from LHR cyl head ( cyl 4 ...I think )

 

Your figure 150......f.....or Celsius ?

 

 

 

[dlegg]

[ATTACH]33111[/ATTACH] [ATTACH]33112[/ATTACH]This works a treat, I can maintain full power indefinitely, Max's to mid green, cruise sets at the bottom green. I've got the numbers somewhere.

Full power, 250f = 121c

 

Cruise........205f = 96c

 

That's reading from LHR cyl head ( cyl 4 ...I think )

 

Your figure 150......f.....or Celsius ?

Celsius. Just how deep is that lip? Mine is 50mm but that looks to be more.

 

 

[01rmb]

yea, dam those idiots that keep having problems hey..

Your words - not mine. I was simply stating that trying to make something that will handle every foreseeable poor handling or maintenance is not possible because people will do something that is not anticipated. But, it was Einstein that said “the definition of insanity is doing the same thing over and over and expecting different results.” If people keep doing something and they keep getting the same bad outcome then maybe it is time to try something different. If they keep having problems you have got to ask yourself why - and maybe a different engine is needed if they can't or won't change what they are doing.

 

Some people are not having the same problems with the Jabiru engine as others so they must be doing something right and it can't be just a bad design. High CHT, high EGT, high oil temp, flight training, increased time since overhaul, fuel, dusty environments and poor operational history are without argument going to be reasonable reasons that you need to increase inspections if you want to avoid a avoid catastrophic engine failure although I concede that I don't believe that it will prevent all engine failures. The Jabiru engine is not a Lycoming, Continental or even a Rotax so the recommendations from Jabiru to undertake increased inspections if you are operating in a high at risk category is a good thing.

 

Certainly an engine used in a training aircraft should be tolerant of poor handling - they are after all students that know no better and are more focussed on keeping the shiny side up than what the temp gauges are showing. The repeated heating and cooling from climbing and idling in circuits is hard on engines and students climbing out at low air speeds will increase the likelihood of problems that will need more frequent inspections. The damage may well be done before the actual failure occurs. Quite possibly Jabiru engines are not tolerant enough of poor handling (time will tell if everyone follows these new recommendations in the service bulletin) and Rotax or other engines maybe a better alternative for training - Cessna after all chose to use a Continental in their 162 (albeit with a 35 odd kg penalty).

 

I have personally seen 4 incidents (1 full engine failure, 2 partial and 1 fuel starvation) in Jabirus. The first was poor quality installation of a gudgeon pin circlip resulting in engine destruction and a forced landing, the other two were poor running as a result of lead fouling from avgas and returned safely to the airfield, the forth ran out of fuel and ended up on a soccer field. This has led me to avoid using avgas and only 98 mogas and ensure there is enough of it in the tanks - as well as making sure that the person touching my engine knows what they are doing.

 

 

[Russ]

About 150mm......the " angle " is a factor as well.

 

Converted to 98 prem, adding moreys top end lube, as per their specs. Pull throughs etc, are always good. Acquaintance talked me into all this, he's accumulated 1500+ hrs! just keeps purring away