Jabiru limitations

[turboplanner]

This is probably what they are talking about but it was analysed and dismissed pretty quickly.Even quicker by some of those backyard dreamers here on the internet TP, your pretty quick to run down a fair bank of skill and experience. Not really sure why you visit these threads

I've been working on hard RAA statistics, and you can write emotional posts until the cows come home, but those statistics are only going to get worse if someone decides to track down unreported engine failure.forced landings.

 

 

[geoffreywh]

quote " jetjrWhat about cylinder cracking mentioned in the instrument?

 

Anyone ever seen this "

 

Yes, first hand, several occurrences............. Happens in conjuction with broken through bolt. Before the bolts breaks or after? who knows? 2 on engines immediately after rebuild. ( By J) Forced landings each time....

 

 

[Oscar]

What about cylinder cracking mentioned in the instrument?Anyone ever seen this

Most of these improvements are in the "short" engine they sell, still stuck with limitations

 

Has CASA even spoken to CAE?

CASA has informed CAMit that a CAE engine is not a Jabiru engine subject to the limitations, but has not (as far as I am aware) been in any contact to find out what CAMit: a) knows about the failures in terms of design, manufacture or use, and b:) what changes (and why!) CAMit makes to its engines to address those problems.

 

In my entirely personal opinion, I believe this is at the very least, lazy work on CASA's part; a conspiracy theorist (moi? - surely not..) would suggest that CASA does not want to hear any 'facts' beyond those it using to justify its current actions. It is commonly considered that Farquharson - the now all-but outgone Acting DAS - was highly antipathetic towards all forms of Sport Aviation having any 'life' beyond CASA's direct control; there are speculative dots that could rather easily be connected to suggest that an action that cuts the guts out of the RAA fleet would be an easy low-hanging fruit for CASA to pick.

 

And before anybody jumps right in there: YES, I agree that Jabiru had placed itself in that position. However, that does NOT, I believe, lead to automatic acceptance that 'the punishment fits the crime', in this case.

 

 

[Oscar]

quote " jetjrWhat about cylinder cracking mentioned in the instrument?Anyone ever seen this "

Yes, first hand, several occurrences............. Happens in conjuction with broken through bolt. Before the bolts breaks or after? who knows? 2 on engines immediately after rebuild. ( By J) Forced landings each time....

Cracking of the cylinder base just above the flange line will almost certainly guarantee a through-bolt failure due to the lever action of the flange against the case ( same action that causes P92 main leg and used to cause early Citabria main leg bolt failures, though in both of those cases there is a fix available). Most likely causes of that are detonation / overtemp operation stretching the through-bolts and allowing the cylinder to hammer, causing fatigue failure / case joining sealant breaking up and allowing hammering to develop.

 

The cracking mentioned in the referenced instrument won't affect the through-bolts, and is probably also caused by the same factors as above, but substitute head-bolt stretching for through-bolt stretching, obviously, and the case sealant degradation wouldn't be a factor..

 

 

[Geoff13]

What about cylinder cracking mentioned in the instrument?Anyone ever seen this

Most of these improvements are in the "short" engine they sell, still stuck with limitations

 

Has CASA even spoken to CAE?

 

quote " jetjrWhat about cylinder cracking mentioned in the instrument?Anyone ever seen this "

Yes, first hand, several occurrences............. Happens in conjuction with broken through bolt. Before the bolts breaks or after? who knows? 2 on engines immediately after rebuild. ( By J) Forced landings each time....

And apparently solved in my understanding by changing the radius at the base of the barrel from 2 to 9 mils and moving the through bolts in closer to the barrel. This gives more metal around the base of the barrel leaving a thicker wall and less chance of flexing. This works toward the through bolt problem as well as the cylinder problem. Don't shoot me if I don't have it perfectly correct but in under 2 hours I was shown so many differences/changes to the Camit engine that I may not have all the detail correct. I feel certain that there may be some here who can it explain it better.

 

The solution to the cylinder rusting mentioned by Oscar above is not as simple as he makes it sound and will need some input from the pilot on shutdown which could cause some issues imho. Although if I were purchasing one I would certainly take this optional extra.

 

The flywheel issue as well as the having the belt driven alternater working as a type of harmonic balancer, also has a much lighter and seemingly better machined flywheel which should also help, as the real issue is because of the fact that there is a flywheel at each end of the Crank.

 

I do not know if Camit have solved all the problems, probably only time will answer that, but they sure as hell have addressed them in a logical and engineering based manner imho. I only hope that they can survive long enough to prove if they have or not. It would be a pity to see Camit fold and find out in 10 years that the motors they have out there are all going strong and making TBO.

 

 

[Kyle Communications]

What about making nickasil bores? I wonder how much extra that would cost.

 

Geoff when you saw Camit I gather they will be closed over the xmas/new year did he happen to tell you? ...I will be in and out of Bundy from this saturday until the following friday or saturday as I will be up at my farm over that period. I would love to call in and just see his operation...not take up wasting his valuable time though. I just can't believe there is so much crap between Jab and them...The Jab engines have such great promise and really could been of the best in the world for price and weight if they were allowed to be developed.

 

Mark

 

 

[Geoff13]

Yep they were in the middle of the clean up for Christmas. Not sure when they were coming back to work.

 

 

[Kyle Communications]

I will find out where they are and cruise past while I am up there

 

 

[Kyle Communications]

Bummer they reopen on the 5th it says on the website....Next time I go up in the new year on the thursday night I will organise the friday to go in and see them

 

 

[Oscar]

Geoff: the base flanges on the CAMit barrels are about 0.8mm thicker than the early Jab ones (not sure about the current Jab ones), as well as having the enlarged radius (sorry, I can't measure it more accurately than that without popping a pot off my dummy engine).

 

Yes, the inhibitor does require pilot operation, I didn't make that clear. It's the 'simplest' practical means to get the effect; Ian Bent does not believe in making things complex if simple will work, but it WILL require just a bit of attention, I agree.

 

Kyle: why not send an email to Ian Bent - [email protected]. He has a family who would, I am pretty sure, dearly like to see their father over the Christmas break, the last period has been frantic for him, but he has such a lot on his dance card at the moment he'll quite possibly be spending some time at his desk, and he is one of the most obliging and patient people you could ever hope to meet when talking about his operation and his engines. The place will be oddly empty without the 'crew' at work, and the sight of some of those seriously large machines turning out a continuous stream of machining waste is really quite an eyeful. The assembly room, without Tony and Trevor calmly assembling engines to almost clinical precision, will seem like an operating theatre awaiting patients - and when you have the lads from the machine shop wheeling in the carts full of shining new pieces ready for assembly, the 'operating theatre' atmosphere is even more apparent.

 

 

[Kyle Communications]

Oscar is your brother FT?

 

 

[geoffreywh]

Note: the crack in the barrel was well above the base. probably 20 or 30 mm. Nothing to do with the radius... But it was on top of the barrel....Tell me again which happened first? ...................

 

 

[Oscar]

Kyle, you could make yourself a whole new enemy by suggesting that! Or two, probably, if FT sees it!.

 

Merry Christmas!

 

 

[Oscar]

Note: the crack in the barrel was well above the base. probably 20 or 30 mm. Nothing to do with the radius... But it was on top of the barrel....Tell me again which happened first? ...................

In THAT case, I'd go with the through-bolt being the most likely culprit, but really, one needs to examine the barrel, the case, and the bolt to get the best idea of which was the chicken.. . However - were there any witness marks on the case of the outer edge of the flange digging into the case? You don't have to have actual cracking at the base flange to get flex in the flange sufficient to break the through bolt.

 

 

[Kyle Communications]

Well try not to be a smart ar&e like him then....of course we all like to see our families and have a break...IF and I stress IF they happened to be open I would call in and have a look at the operation seeing they are extremely busy and I didn't know if they were going to close or not....note the last part of my post. Many a year I have had to work through the holiday period for my business and I am sure Ian has done the same thing. Anyone who has run a business for a long time has to do things when they have to be done. It was nothing more than going in for a quick look if they were open.

 

I import CNC machines for my other company although nothing like they use of course. You also do not know what I have planned in the future for another aircraft I am considering building and what engine I will put in it.

 

 

[geoffreywh]

No Oscar, no witness marks. My best guess is that the barrel broke first, then the bolt....Detonation? again...the engine was (2200) 20 hours old...I hope that the CASA intervention can encourage J. to find a cure and stop this sort of thing from happening again.

 

 

[jetjr]

Seeing as much of the fuel distribution problem appears to be coming from airbox and feed to carb, not swapped at engine change, its highly likely if it happens once it will again.

 

Dont suppose you had EGT and CHT on all cyl?

 

Theres some good reasons why an operator might have repeated problems especially low hour failures after rebuilt.

 

 

[Geoff13]

Note: the crack in the barrel was well above the base. probably 20 or 30 mm. Nothing to do with the radius... But it was on top of the barrel....Tell me again which happened first? ...................

The way it was explained to me it could have plenty to do with the radius. The larger radius and thicker wall support the barrel for the length of itself. The stronger base means a stronger mount means less flex at the base. Less flex at the base will mean less flex further up as well as less pressure on the through bolts. Like I say I am no design engineer but the explanation and description seemed very logical to me.

 

Oscar like I said if I were buying one of their engines, (which could happen yet) I would certainly go for the oil system. I think it is simple and a very good idea. I like the KISS principle as well, it is an area though that could be poorly used if in a training situation with student pilots. Having said that it would be unnecessary in a motor that was being used every day like a training aircraft.

 

 

[Russ]

LAME that did my topend refurbish 6 mths ago, payed particular attention to the refitting of the 4 inlet tubes to the heads. He said relying on the single O rings was not good enough, he as well, placed a small ring of silicon just inside each joint, as the tubes came together, the silicon created that extra seal. ( where the tubes entered that alloy distribution box.) he noted at the dismantle stage that a couple of cyls were running leanish. Hence his usual practice of better sealing.

 

Now done close to 100hrs, and checking plugs the other day, they all looked uniform in colour. The comment was....perfect.

 

 

[Oscar]

No Oscar, no witness marks. My best guess is that the barrel broke first, then the bolt....Detonation? again...the engine was (2200) 20 hours old...I hope that the CASA intervention can encourage J. to find a cure and stop this sort of thing from happening again.

Well, that is a weird one, for sure - and the sort of thing that really needs to be added to the list to be thoroughly investigated, because it adds to the sum of knowledge about what sort of failures are happening and most crucially, what is the 'chain' of circumstances. I have absolutely no difference of opinion with those who say that Jabiru's 'normal' reaction to failure reporting is neither a sufficient nor an adequate response in many cases, though to be fair, that does not mean that Jabiru is automatically always wrong. It ALSO does not mean they are always automatically right- quite obviously.

 

The lack of decent, at least quasi-forensic, examination of engine failures plus proper remedial research and design improvements has put Jabiru in the situation in which it is now placed; I can't see any sensible argument against that. However, it is very likely that most of the failures that have occurred are not just due to a single factor but a combination of factors and it is this chain of circumstances that needs to be discovered.

 

 

[Oscar]

Well try not to be a smart ar&e like him then....of course we all like to see our families and have a break...IF and I stress IF they happened to be open I would call in and have a look at the operation seeing they are extremely busy and I didn't know if they were going to close or not....note the last part of my post. Many a year I have had to work through the holiday period for my business and I am sure Ian has done the same thing. Anyone who has run a business for a long time has to do things when they have to be done. It was nothing more than going in for a quick look if they were open.I import CNC machines for my other company although nothing like they use of course. You also do not know what I have planned in the future for another aircraft I am considering building and what engine I will put in it.

Kyle, I have no idea why you would have taken such offence at a suggestion that Ian Bent might be at CAMit over the Christmas break and would quite possibly be happy to show you around if you happened to be in the area at the time. He just is that sort of person anyway and is very proud of his operation, with good reason. He was prepared to come in from home and open the place on a weekend to allow my co-owner and I to keep on working on our engine rebuild when I was last up there, to drop what he was working on when we needed something special for our somewhat 'bitzer' build, and to show us the FEA analysis, CAD drawings etc. behind changes (and to check that changed components would work properly in the case of our specific engine), to teach us how to machine cases and heads, to make jigs and tooling himself because some parts of our engine were older than the engines for his existing jigs and tools.

 

 

[DCM]

Kyle, I have no idea why you would have taken such offence at a suggestion that Ian Bent might be at CAMit over the Christmas break and would quite possibly be happy to show you around if you happened to be in the area at the time. He just is that sort of person anyway and is very proud of his operation, with good reason. He was prepared to come in from home and open the place on a weekend to allow my co-owner and I to keep on working on our engine rebuild when I was last up there, to drop what he was working on when we needed something special for our somewhat 'bitzer' build, and to show us the FEA analysis, CAD drawings etc. behind changes (and to check that changed components would work properly in the case of our specific engine), to teach us how to machine cases and heads, to make jigs and tooling himself because some parts of our engine were older than the engines for his existing jigs and tools.

Oscar

I have to agree with you Ian is one of natures gentlemen and always happy to help

 

David

 

 

[dmech]

Note: the crack in the barrel was well above the base. probably 20 or 30 mm. Nothing to do with the radius... But it was on top of the barrel....Tell me again which happened first? ...................

Hi geoffreywy, I will take a punt here , that cracked barrel , I reckon it was on the oil filter side of the engine, could you let me know also which side your bolts broke and wether top or bottom, the indications I get is that it is top bolts on oil filter side, bottom bolts on other side, same with barrels, most common. this is not caused by detonation !.

A.D

 

 

[Kyle Communications]

Oscar

 

Have been in business for 30 years and I would never impinge on anyones family/holiday time as it has been done to me almost countless times by people who think you are at work 24/7 and are inconsiderate of people who run their businesses and put a lot of effort into them. Your second sentence I thought was aimed at me being inconsiderate. If not then I am sorry for the inference. I would never ask him to be there if it wasn't important and almost life threatening and this isn't. So I will organise it when next I am up there on a normal weekday

 

 

[dazza 38]

For clarity it is Mark Kyle, Kyle isn't his first name. He is too polite to say anything. But me being me, I thought I should say something. Anyway as some are aware, I did my pilot cert in a Jab LSA back in 1998 and honestly, things haven't changed much since then.

 

Actually, I finished my cert in a Jab, I soloed in a drifter at the 11 hour mark and my training up until that stage was done with HITC who is a member here. The 582 2 stroke Rotax was more reliable by my experience compared to the Jab anchor.