"Jaberoo" down (Mildura this time)

[Dafydd Llewellyn]

I have raised this before (see http://www.recreationalflying.com/threads/another-engine-failure.118777/page-3#post-431173).In my case, if not for being picked up during the 300 hr service I would have had a full engine failure, possibly in flight, due to the exhaust valve stem breaking off inside the cylinder. The problem was traced to burning of the exhaust valve and stem as a result of lead fouling from avgas preventing a proper seal of the valve. This inhibited cooling of the exhaust valve leading to the valve being burnt away exposing the valve stem to the combustion heat which within a few more hours would have broken off. I would not have expected CHT to pick up this problem only EGT.

 

Identified, fixed and no longer using avgas with no further issue.

Thanks; that's most interesting. To my understanding, lead fouling occurs when the engine is running too cool for the bromine in the TEL mixture to react with the lead, forming lead bromide, which is carried away by the exhaust. It was a well-known issue with Lycomings etc used for training, especially on 100/130 AVGAS, but in the spark plugs usually. Didn't get it much when cruising at lean mixture. Were you doing a lot of idling on the ground, or other low-power operation? Also, which cylinder was it?

 

 

[jetjr]

Trouble with fuel mixtures in 3300, is that some cylinders are running rich, some bordering on lean, and at differing rpm it all changes around

 

I was told that for my older thick finned heads, (at the time of the lean jet kit problems) fuel to aid cooling was cheap.. Keep egt below 700, and cht below 120. Right now i have this but one side has cht nearer 100, trying to warm it up a little.

 

Egt are below 700 but some way too cool -600, to achieve this

 

Another fact of the development is that the fine finned heads, pretty much coincided with hydraulic lifter introduction. They certainly run much cooler.

 

But the problem rate for hydraulic engines may have overshadowed benefits. I think valve problems and head torque issues seen in older versions went away but through bolt problems developed

 

In my uneducated opinion, fuel distribution has a lot to do with random aspect of the issues. Some have excellent egt spread some very poor. Interestingly my poor spread followed across from one engine to another so is air intake based. Stuffed if i can fix it though.

 

 

[turboplanner]

That makes sense to me when I look at the inlet manifolding.

 

 

[Old Koreelah]

I fear getting a dodgy batch of petrol so I use only AvGas. My 2.2 runs pretty cool, so I also fear lead buildup on valve stems. With the oft-predicted demise of AvGas, fuel injection is looking like a logical solution. I believe a bloke in South Australia has much experience in this area, having worked on EFI for Mitsubishi and installed several systems on Jabs. He would sure be an asset to this discussion.

 

 

[01rmb]

Thanks; that's most interesting. To my understanding, lead fouling occurs when the engine is running too cool for the bromine in the TEL mixture to react with the lead, forming lead bromide, which is carried away by the exhaust. It was a well-known issue with Lycomings etc used for training, especially on 100/130 AVGAS, but in the spark plugs usually. Didn't get it much when cruising at lean mixture. Were you doing a lot of idling on the ground, or other low-power operation? Also, which cylinder was it?

It was cylinder 4 of a 3300. Cylinder 3 was well on the way but all the other heads were fouled as well but without valve problems. Compression dropped quickly and started to not idle as smooth as it normally does. Cleaning the heads and replacing the valves sorted it out.

 

The use of the aircraft typically requires a bit of idling due to the nature of the airport which requires a fairly long taxi before and after flight exasperating the problem. A number of other aircraft at the site had similar issues which were solved by running mogas.

 

This is my explanation on lead fouling from earlier http://www.recreationalflying.com/threads/another-engine-failure.118777/page-2#post-429839. Fouling can occur around the plugs and only cause the engine to run rough but it does also occur around the exhaust valves as well. With engines with lower design tolerances it won't make much of a difference but with the Jabiru engine's critical fine tolerances it makes a big difference and quickly.

 

This is why I feel that the typical engine tests where the engine is run at full power does not take into account the real world usage and is hiding some operational issues that are only getting picked up on the fields.

 

 

[Oscar]

The use of the aircraft typically requires a bit of idling due to the nature of the airport which requires a fairly long taxi before and after flight exasperating the problem. A number of other aircraft at the site had similar issues which were solved by running mogas.

This is why I feel that the typical engine tests where the engine is run at full power does not take into account the real world usage and is hiding some operational issues that are only getting picked up on the fields.

This sort of information - regarding the 'profile' of actual operation - is extremely valuable. We know that some owners/operators have a run of issues, (and often, fairly typically similar issues at similar hours of operation) while others, conversely, have a run of very satisfactory service, even in 'school' use. People get, understandably and reasonably, upset if questions /suggestions / allegations (choose the term that suits you) of 'operation' are raised in connection with problems, because that tends to carry an assertion that 'you have abused this engine', when they have (as far as they know) done everything correctly and by the book.

 

With the exception of one report I have heard of a (GA) pilot who hired a Jab (out of Wedderburn, I think it was, years ago) and noticed the cht going overtemp so 'climbed as hard as I could to get height' (the engine grenaded, jeez who'd have thought?), I very, very much doubt that any owner/operator wilfully 'abuses' an engine. However, full reporting and recording of engine performance (chts and egts on all cylinders) has a way better chance of an operator developing an understanding of what is actually happening at all stages of engine use, and it may well be that some slight changes in use can make a considerable difference to engine reliability.

 

The full-power running used in testing demonstrates the limits of the engine, and its ability to operate TO those limits. The flight instrumentation is there mainly to provide information that the engine is operating WITHIN those limits, and as I think we all, from either 'side' of the debate, acknowledge that Jabs. are finicky about those limits and also have variability in installation etc. that requires considerable vigilance on the part of the operator. If all the requisite information is not available to the operator, then he/she can hardly be blamed for not being aware of something that is potentially/actually harmful to the engine happening.

 

 

[Dafydd Llewellyn]

Trouble with fuel mixtures in 3300, is that some cylinders are running rich, some bordering on lean, and at differing rpm it all changes aroundI was told that for my older thick finned heads, (at the time of the lean jet kit problems) fuel to aid cooling was cheap.. Keep egt below 700, and cht below 120. Right now i have this but one side has cht nearer 100, trying to warm it up a little.

Egt are below 700 but some way too cool -600, to achieve this

 

In my uneducated opinion, fuel distribution has a lot to do with random aspect of the issues. Some have excellent egt spread some very poor. Interestingly my poor spread followed across from one engine to another so is air intake based. Stuffed if i can fix it though.

Here's what Ian McPhee did to improve the mixture distribution in his Jabiru-engined motorfalke; the first attachment shows the upper end of the "cobra-head" duct that was necessary for that installation; the second shows the outlet from the carburettor air selector / filter box. The purpose of these is to de-swirl the air entering the carburettor. The fuel spray leaving the carburettor is deflected up or down by the position of the throttle butterfly; and if the airflow is swirling as it passes through the carburettor, the fuel spray will be deflected sideways as well. That will cause a mixture mal-distribution in the plenum. The swirl is likely to be generated in the airbox, and it will intensify, like water going down a plughole, as it flows into the airbox outlet. Anything of this sort must be located downstream of the hot-air selector, or it will present an induction ice hazard.

 

 

 

 

[Marty_d]

Question from someone not particularly mechanically minded. Have I got this right?

 

• Most aircraft engines, like the Jab, are air-cooled.
   
   
  
• This is presumably to save weight.
   
   
  
• However it seems that unless the engine is perfectly mounted and baffled, you will never get even cooling to each cylinder head.
   
   
  
• Most car engines are water cooled. Does this deliver more even and better regulated cooling?
   
   
  
• I assume that in most situations, power output per kilogram of weight would be lower for a water-cooled engine than an air-cooled one.
   
   
  

 

 

If all this is generally accurate - why aren't there more water-cooled aero engines out there? Is the weight penalty that much more? In fact, as regards the Mazda post a while back - given the increasing numbers of people interested in owning their own light aircraft, and the fact that they can't all be mechanics / test pilots / engineering geniuses, why isn't there an EFI water-cooled engine that just runs reliably?

 

Feel free to beat me over the head if what I ask is particularly stupid!

 

 

[Dafydd Llewellyn]

It was cylinder 4 of a 3300. Cylinder 3 was well on the way but all the other heads were fouled as well but without valve problems. Compression dropped quickly and started to not idle as smooth as it normally does. Cleaning the heads and replacing the valves sorted it out.The use of the aircraft typically requires a bit of idling due to the nature of the airport which requires a fairly long taxi before and after flight exasperating the problem. A number of other aircraft at the site had similar issues which were solved by running mogas.

 

This is my explanation on lead fouling from earlier http://www.recreationalflying.com/threads/another-engine-failure.118777/page-2#post-429839. Fouling can occur around the plugs and only cause the engine to run rough but it does also occur around the exhaust valves as well. With engines with lower design tolerances it won't make much of a difference but with the Jabiru engine's critical fine tolerances it makes a big difference and quickly.

 

This is why I feel that the typical engine tests where the engine is run at full power does not take into account the real world usage and is hiding some operational issues that are only getting picked up on the fields.

Thanks again. The test schedule required by certification standards such as JAR 22 and FAR 33 is what the applicant is required to do, and as you say, it does not address the lower-power operations that occur in actual service very well. The aircraft's certification flight testing generally requires about 25 hours of flying if all goes well; but test pilots do not tend to muck about on the ground; once I'm comfortable with the powerplant, I usually do my engine checks whilst taxiing to avoid picking-up gravel; so the engine does not get exposed to the sort of delays one finds at a busy airfield.

I'm not sure what can be done in the engine design area to reduce this problem (if indeed anything can be done); the issue with AVGAS is that, unlike the old leaded "Super" car fuel, the TEL mixture does not contain an excess of bromide to clean up the lead despite the variable running conditions in a motor vehicle (it used to contain 2 to 3 times the chemical equivalent of the lead), AVGAS is only permitted to contain the precise chemical equivalent of the lead. I used to use a mixture of Super and AVGAS in my PA 28 for this reason, and it did keep the plugs clean and the valves from sticking - but one cannot do that nowadays, because only 100LL still contains lead, and no fuel to my knowledge contains excess bromine.

 

There's a product - a fuel additive - called "Decalin" - that is supposed to help remove lead deposits from valves; I've not tried it; I wonder does anybody have any experience with it?

 

 

[Dafydd Llewellyn]

Question from someone not particularly mechanically minded. Have I got this right?

 

• Most aircraft engines, like the Jab, are air-cooled.
   
   
  
• This is presumably to save weight.
   
   
  
• However it seems that unless the engine is perfectly mounted and baffled, you will never get even cooling to each cylinder head.
   
   
  
• Most car engines are water cooled. Does this deliver more even and better regulated cooling?
   
   
  
• I assume that in most situations, power output per kilogram of weight would be lower for a water-cooled engine than an air-cooled one.
   
   
  

 

 

If all this is generally accurate - why aren't there more water-cooled aero engines out there? Is the weight penalty that much more? In fact, as regards the Mazda post a while back - given the increasing numbers of people interested in owning their own light aircraft, and the fact that they can't all be mechanics / test pilots / engineering geniuses, why isn't there an EFI water-cooled engine that just runs reliably?

 

Feel free to beat me over the head if what I ask is particularly stupid!

It's a fair question; and liquid cooling can indeed make it easier to get uniform cooling.

However, ultimately the heat rejected by the engine has to be carried away by the air; and shifting heat from A to B requires that B must be cooler than A - as Flanders & Swan put it: "Heat won't flow from a cooler to a hotter; you can try it if you like, but you're far better notter". (Second law of thermodynamics).

 

A liquid-cooled engine has to shift the heat three times - firstly, from the engine metal to the coolant; and then from the coolant to the radiator metal; and then from the radiator metal to the air; so it has to divide the available temperature difference into three parts. So it's not that easy to achieve overall cooler engine running that way. In fact, most liquid-cooling systems use pressurisation and glycol to allow the engine temperature to be raised, in order to increase the available temperature difference.

 

Secondly, a liquid-cooling system significantly increases the potential failure modes; air cooling is much more defensible in court. Given the way the American product-liability situation affected aircraft manufacturers there in the 1980s, I doubt any American aircraft engine manufacturer would dare build a liquid-cooled engine. Rotax originally tried both air-cooled and liquid-cooled versions of the 912; I saw both prototypes in their development shop in 1985. They finally chose the liquid-cooled heads because it was primarily a motor-glider engine, and glider pilots cannot be relied upon to cool the engine gradually before shutting it down. The choice has worked for them, but it makes the engine very messy to install.

 

Thirdly, liquid-cooled heads tend to be prone to local boiling, which can result in the steam "blowing" the water out of the head - which then "cooks" in seconds. This has been a problem in several of the later Peugeots that we have had, so car engines are by no means immune to this. It helps if the heads are at the lowest point in the cooling system, which makes me wonder why we do not have inverted V-layout aircraft engines; a de-gassing bottle is a real necessity, and Rotax provide one for the 582.

 

Finally, research was done back in the 1920s and 1930s - I think by H Roxbee-Cox, at RAE, which showed, surprisingly, that the exhaust valve temperatures of air-cooled and liquid cooled cylinders were pretty much the same. That was with the cylinders available at that time, but most of the fundamental research into aircraft piston engines was being done then; after about 1940 the research was into jets, and has been ever since.

 

 

[Marty_d]

It's a fair question; and liquid cooling can indeed make it easier to get uniform cooling.However, ultimately the heat rejected by the engine has to be carried away by the air; and shifting heat from A to B requires that B must be cooler than A - as Flanders & Swan put it: "Heat won't flow from a cooler to a hotter; you can try it if you like, but you're far better notter". (Second law of thermodynamics).

 

A liquid-cooled engine has to shift the heat three times - firstly, from the engine metal to the coolant; and then from the coolant to the radiator metal; and then from the radiator metal to the air; so it has to divide the available temperature difference into three parts. So it's not that easy to achieve overall cooler engine running that way. In fact, most liquid-cooling systems use pressurisation and glycol to allow the engine temperature to be raised, in order to increase the available temperature difference.

 

Secondly, a liquid-cooling system significantly increases the potential failure modes; air cooling is much more defensible in court. Given the way the American product-liability situation affected aircraft manufacturers there in the 1980s, I doubt any American aircraft engine manufacturer would dare build a liquid-cooled engine. Rotax originally tried both air-cooled and liquid-cooled versions of the 912; I saw both prototypes in their development shop in 1985. They finally chose the liquid-cooled heads because it was primarily a motor-glider engine, and glider pilots cannot be relied upon to cool the engine gradually before shutting it down. The choice has worked for them, but it makes the engine very messy to install.

 

Thirdly, liquid-cooled heads tend to be prone to local boiling, which can result in the steam "blowing" the water out of the head - which then "cooks" in seconds. This has been a problem in several of the later Peugeots that we have had, so car engines are by no means immune to this. It helps if the heads are at the lowest point in the cooling system, which makes me wonder why we do not have inverted V-layout aircraft engines; a de-gassing bottle is a real necessity, and Rotax provide one for the 582.

 

Finally, research was done back in the 1920s and 1930s - I think by H Roxbee-Cox, at RAE, which showed, surprisingly, that the exhaust valve temperatures of air-cooled and liquid cooled cylinders were pretty much the same. That was with the cylinders available at that time, but most of the fundamental research into aircraft piston engines was being done then; after about 1940 the research was into jets, and has been ever since.

Thanks Dafydd - very informative.

 

 

[01rmb]

Thanks again. The test schedule required by certification standards such as JAR 22 and FAR 33 is what the applicant is required to do, and as you say, it does not address the lower-power operations that occur in actual service very well. The aircraft's certification flight testing generally requires about 25 hours of flying if all goes well; but test pilots do not tend to muck about on the ground; once I'm comfortable with the powerplant, I usually do my engine checks whilst taxiing to avoid picking-up gravel; so the engine does not get exposed to the sort of delays one finds at a busy airfield.I'm not sure what can be done in the engine design area to reduce this problem (if indeed anything can be done); the issue with AVGAS is that, unlike the old leaded "Super" car fuel, the TEL mixture does not contain an excess of bromide to clean up the lead despite the variable running conditions in a motor vehicle (it used to contain 2 to 3 times the chemical equivalent of the lead), AVGAS is only permitted to contain the precise chemical equivalent of the lead. I used to use a mixture of Super and AVGAS in my PA 28 for this reason, and it did keep the plugs clean and the valves from sticking - but one cannot do that nowadays, because only 100LL still contains lead, and no fuel to my knowledge contains excess bromine.

 

There's a product - a fuel additive - called "Decalin" - that is supposed to help remove lead deposits from valves; I've not tried it; I wonder does anybody have any experience with it?

And this is the problem. The manufacturer complies with the standards but the standards don't reflect the environment and thus problems are occurring. Run the engines at full power within specification is proven to not be a problem - but in real life usage incidents are occurring.

 

It could be fixed with a 'better' engine design (but how given the limitations), maybe a different fuel choice, possibly an additive to remove the problem, handling practices that help alleviate the idling time or maybe a different maintenance practice/schedule to accommodate the consequences of the design, fuel and actual usage. Jabiru went some way there with changing the recommended oil change schedule due to contamination of the oil from the left over lead in the fuel. A 300 hour head removal and valve clean is dramatic but it may be needed if there is a certain level of idling time when avgas is used. Certainly better than a forced landing in a suburban street...

 

Problems are not occurring for everyone and that is the point - what are the differences that are causing problems? And I don't believe it is just user maintenance or poor handling at fault!

 

 

[Oscar]

Problems are not occurring for everyone and that is the point - what are the differences that are causing problems? And I don't believe it is just user maintenance or poor handling at fault!

Absolutely, screamingly correct - and that's why collecting (and sharing) in-depth information about the causes of failures ( including failure to meet a decent TBO schedule) would be of immense value. Maintenance is fairly easy to deduce, if the log-books are kept scrupulously, but it would help, I believe, if users had a sort of 'User Guide' - not the POH itself, but more in the nature of 'tips and things to watch out for' that would provide them with a much better picture of how the 'systems' all interlink. That would indicate areas to watch closely, and with sufficient reliable information being reported to them and explanations in the 'User Guide' as to what the sort of numbers they are getting and when might mean, they have a fighting chance of being able to deduce ways to avoid venturing into critical areas, whether that be in terms of their pattern of operation, the performance of their cooling installation, their fuel mixture distribution under particular conditions of flight etc.

 

 

[aj_richo]

a mechanic at tyabb has solved the cooling problem and their is a picture of his 3300 install in the RAA magazine a few monthes ago of the Bristell with a jab enginehe build a proper plenum chamber like a Cessna

I heard recently from someone who contacted Bristel to get info on their cooling setup.. they said they had gone back to jabiru cooling ducts.

 

 

[Dafydd Llewellyn]

And this is the problem. The manufacturer complies with the standards but the standards don't reflect the environment and thus problems are occurring. Run the engines at full power within specification is proven to not be a problem - but in real life usage incidents are occurring.It could be fixed with a 'better' engine design (but how given the limitations), maybe a different fuel choice, possibly an additive to remove the problem, handling practices that help alleviate the idling time or maybe a different maintenance practice/schedule to accommodate the consequences of the design, fuel and actual usage. Jabiru went some way there with changing the recommended oil change schedule due to contamination of the oil from the left over lead in the fuel. A 300 hour head removal and valve clean is dramatic but it may be needed if there is a certain level of idling time when avgas is used. Certainly better than a forced landing in a suburban street...

 

Problems are not occurring for everyone and that is the point - what are the differences that are causing problems? And I don't believe it is just user maintenance or poor handling at fault!

Yes, you're dead right. The difference is what we urgently need to discover. Ian Bent is working on a "better" engine; but there's still obviously something out there that affects engines quite separately to any marginal design. So far we have two contenders - lead fouling causing valve sticking marginally open; and changes in mixture distribution due to (a) Carburettor being re-installed slightly tilted; (b) Change in airflow "swirl" due to minor changes in the induction duct geometry (I've seen some very distorted airbox outlets) - and, possibly but far from proven, air leak into one of the manifold joints at the point where the distribution tubes connect to the plenum. Keep the reports coming in, please.

 

 

[Guest Andys@coffs]

So we know Rod has a fairly firm view on a non carburetted approach, What position does Ian take, for those closer to him?

 

I have heard that Rotax are having all sorts of fun with their injected 912, but I guess that's to be expected with ver 1.0 of anything.

 

That said with these J engines what exactly constitutes a version? It seems to me that as things are done to an engine it gains some of the newer stuff but has some of the older stuff on it, perhaps in doing that creating a unique instance...I guess that doesn't exactly help.

 

Andy

 

 

[bexrbetter]

Most (light) aircraft engines, like the Jab, are air-cooled.

This is presumably to save weight.

Correct. But very little difference. However, the aircooled is by far cheaper to make and install.

 

Most car engines are water cooled. Does this deliver more even and better regulated cooling?

In theory yes..

 

I assume that in most situations, power output per kilogram of weight would be lower for a water-cooled engine than an air-cooled one.

Only true up to a moderate output.

 

Is the weight penalty that much more?

Rotax prove it's not.

 

why isn't there an EFI water-cooled engine that just runs reliably?

Market size, why go out of your way to build 20,000 expensive engines that you may be sued over when you can sell 2 million cheap ones and take less care.

 

 

[fly_tornado]

a work of art

 

 

 

[motzartmerv]

With the exception of one report I have heard of a (GA) pilot who hired a Jab (out of Wedderburn, I think it was, years ago) and noticed the cht going overtemp so 'climbed as hard as I could to get height' (the engine grenaded, jeez who'd have thought?), I very, very much doubt that any owner/operator wilfully 'abuses' an engine.

.

I would do the same thing..And have actually.. Ive opted to squeeze the last remaining goodness form a dieing engine to help me, and any pilot with half a brain would do the same thing (I would hope). No point nursing an engine while you eat gum trees!!!

 

 

[Oscar]

Yes, you're dead right. The difference is what we urgently need to discover. Ian Bent is working on a "better" engine; but there's still obviously something out there that affects engines quite separately to any marginal design. So far we have two contenders - lead fouling causing valve sticking marginally open; and changes in mixture distribution due to (a) Carburettor being re-installed slightly tilted; (b) Change in airflow "swirl" due to minor changes in the induction duct geometry (I've seen some very distorted airbox outlets) - and, possibly but far from proven, air leak into one of the manifold joints at the point where the distribution tubes connect to the plenum. Keep the reports coming in, please.

I can certainly verify the fact that some - at least - airboxes are quite foul - mine is (and absolutely does NOT conform to Jab's instructions for airbox finishing), but then my aircraft was used as a test mule for the development of the 2200 and there is some truly dreadful cobbled-up work in the whole airbox and cowl area, which was never rectified (and may have been exacerbated) by what is incontrovertible evidence of lousy maintenance practices over many years. Since it was originally VH-reg (the first one for Jab) and subsequently moved to 55-reg, that maintenance was carried out by LAMEs /L2's, and some of it would disgrace a billycart. We're talking about stuff of just about the same quality as fencing-wire and re-used bent staples, but with an aeronautical twist to them.

 

The fact that the poor little bugger kept on flying, in school use, for so many years - albeit with too-frequent engine problems - is mute testimony to the fact that even Jab engines will tolerate SOME abuse, just not for long.

 

 

[Dafydd Llewellyn]

So we know Rod has a fairly firm view on a non carburetted approach, What position does Ian take, for those closer to him?I have heard that Rotax are having all sorts of fun with their injected 912, but I guess that's to be expected with ver 1.0 of anything.

 

That said with these J engines what exactly constitutes a version? It seems to me that as things are done to an engine it gains some of the newer stuff but has some of the older stuff on it, perhaps in doing that creating a unique instance...I guess that doesn't exactly help.

 

Andy

Andy, you should really ask Ian that question re fuel injection. He can see, just as the rest of us can, that with the likely future variability of fuel, multi-point FI with knock sensing is likely to be the only viable answer. It would also get rid of the mixture distribution hassle and make life easier in regard to induction icing. However, it's a very major step to certificate; and I think it's on the shelf just at present. But I'm not Ian's mouthpiece.

I've looked at a fuel-injected Limbach installation in a Grob 109, and I did NOT like what I saw; it required a split electrical system, for a start, because electrical failure will stop an electronic FI system. To give just one example - what happens to an electronic FI system if the alternator voltage regulation setup fails? A carbie does not give a damn what the electrical system is doing - it just goes on working. It also looked to me like an engine fire going somewhere to happen; there was no way it could be made to meet normal certification standards for powerplant fire protection. Any system simply transplanted from a car, seems likely to have those objections, from what I have seen of them; but those are the minor bits; the major bit is certificating the computer that controls it. One approach is to keep the carburettor and its manifolding etc, as a fall-back; but that raises the same problem as the proverbial theatre emergency lighting system that is never checked; when you want it to work, it very likely won't.

 

What Ian is doing is developing a set of modifications that are, individually, classified as minor modifications, to be approved by putting them all on a specimen engine and running it through the JAR 22 certification endurance test, (once Ian has finished flogging them on his own J230; he has an impressive pile of ruined cylinder barrels already). That will give Ian a bunch of approved modifications that he can assemble as he sees fit. Exactly how they will be applied is still undecided, I think - but one obvious option would be for CAMit to set up an engine overhaul shop, and using repair-by-replacement, overhaul existing Jabiru engines and bringing them up to an identified CAMit standard in the process. They would be Jabiru engines with the CAMit rebuild, and would be data-plated as such, I expect - which I assume must transfer the liability for them from Jabiru to CAMit; but I'm guessing, here.

 

Another option would be for CAMit to apply for a supplemental type certificate for the rebuild - which would definitely transfer the liability.

 

A third option is for CAMit to obtain a full TC for the modified engine and start manufacturing them from scratch.

 

You will appreciate that these are somewhat academic distinctions, since CAMit builds all the bits in the first place - but from CASA's point of view, the differences are real. I think you will in due course see all these stages applied.

 

 

[Marty_d]

a work of art

Dear Santa,

 

Please may I have one of these for Christmas? I'll be ever so good.

 

 

[Oscar]

I would do the same thing..And have actually.. Ive opted to squeeze the last remaining goodness form a dieing engine to help me, and any pilot with half a brain would do the same thing (I would hope). No point nursing an engine while you eat gum trees!!!

Merv - Wedderburn is one site for which I can certainly understand the fear of not having enough height - but it's debatable as to whether this engine was actually dieing, or just being flogged unmercifully. We don't know. I've had the delightful experience of having to nurse a dieing Commodore (ring a bell?), with a Jabiru on a trailer behind it - along in 32C+ conditions when the EFI rail pressure relief valve decided to go troppo; it called 'uncle' about 2/3rds up the first Moonbi range hill. Not a nice place to come to a juddering halt.

 

Every situation has its peculiarities and unless you are the PIC at the time, your decisions have to be the best judgement available at the moment. However, it isn't necessarily the fault of the engine if you decide that the best course of action is to extract the last breath from it - especially if a different action might have reduced/removed the problem. We all know the apocryphal 'turn up the radio to drown out the knocking noise from the engine' story..

 

 

[Dafydd Llewellyn]

Dear Santa,Please may I have one of these for Christmas? I'll be ever so good.

Don't forget to ask Santa for a maintenance contract, whilst you're at it. Same as for any other engine, but more complicated.

 

 

[Oscar]

So we know Rod has a fairly firm view on a non carburetted approach, What position does Ian take, for those closer to him?I have heard that Rotax are having all sorts of fun with their injected 912, but I guess that's to be expected with ver 1.0 of anything.

 

That said with these J engines what exactly constitutes a version? It seems to me that as things are done to an engine it gains some of the newer stuff but has some of the older stuff on it, perhaps in doing that creating a unique instance...I guess that doesn't exactly help.

 

Andy

Andy - when up at CAMit last year, I saw two engines with injector ports on the intake tubes, ready to push out of the engine assembly shop. I think (though don't take this as gospel, I was too busy to delve into it) that these were for Jabiru to deliver to an Israeli drone manufacturer; I seem to remember Sue Woods mentioning in an interview in Sport Pilot that they have been supplying engines for drones.

 

So, progress is being made towards incorporating EFI on Jab engines, but the regulatory requirements are a major hurdle before we'll see them in aircraft. It will happen... but not overnight...