"Jaberoo" down (Mildura this time)

[fly_tornado]

I saw video of a guy in France who fitted clear valve covers to monitor the oil flow to his valves as part of an experiment to fix the poor oil flows to the heads.

 

 

[Oscar]

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

 

 

[David Isaac]

I am actually surprised you can see much with all the oil that should be splashing about in the rocker covers. But if it is working correctly perhaps you can see four little splash contact points on the clear covers.

 

 

[David Isaac]

Does anyone know if Camit have stayed with hydraulic lifters or have they gone back to solid lifters. Do they use a conventional cam lobe to lifter radius contact or roller followers?

 

 

[Oscar]

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

 

 

[Dafydd Llewellyn]

I am actually surprised you can see much with all the oil that should be splashing about in the rocker covers. But if it is working correctly perhaps you can see four little splash contact points on the clear covers.

Mind you, the oil flow is just one of a number of factors. Provided the guides were reamed correctly, so the valve did not go into its seat off-centre as initially assembled, then the excessive clearance is very likely due to the guide getting just a bit too hot. The guide will inevitably get a lot of heat from the valve, and it has to get rid of that heat in various ways - oil flow is one, thermal conduction into the cylinder head is another - if the engine had run at almost any time with too high a CHT, for whatever reason, that makes it harder for the valve guide to get rid of its heat, and that could start the process. Rocker geometry has a potential part to play, too.

If one draws a "causation tree" it becomes obvious that what may seem simple is in fact very complex. One might learn something from a detailed examination of the other three heads.

 

 

[Guest Andys@coffs]

K liners....Rod Stiff says absolutely Not......others say fit them if your registration allows..... a search on this forum will bring up some history of people using them....

 

The fact that the guides can wear out well before reaching the overhaul times is telling in my view as there isn't much a user can do to exacerbate wear other than bugger up the solid lifter clearances (and to be honest if you cant do that job then don't touch anything else, pay a L2 to do it!), or run the engine too hot, and if you have just the factory supplied CHT or EGT gauges fitted which at best cover only some of your cylinders, then how as a user can you know if your running too hot...... A claim of poor user maintenance is a useful as a claim that the user was unable to hold his breath for 5 minutes repeatedly......surprising that!

 

Andy

 

 

[Dafydd Llewellyn]

Andy, I agree wholeheartedly; I want full CHT / EGT data for all cylinders of any engine in my aircraft. I recommend that people fit a recording EMS system; it can be done as an add-on to the basic required instruments. In anything up to and including a J 160C, that would be a trivial approval exercise under CASR 21M. If you have one of the LSA models, I doubt Rod would object to it as an add-on, though he may well object to it as an instead-of. If you have one under -19, just do it.

 

I don't want to get into a debate about "I shouldn't have to do that on a 'certified' aircraft", etc - I would just want such an instrument, by whatever means. I'd go find the means.

 

The accident that started this thread could have a cause as remote as a distorted outlet on the air selector box, causing swirl in the induction duct and thus a mixture mal-distribution. Only a full set of temperature instruments will allow one to see something like that coming, and it may take years to develop.

 

 

[jetjr]

Dynon ems is an option on LSA aircraft from Jabiru

 

Make sure logging is turned on

 

Cheap insurance and has been discussed at length yet still operators cannot say if their engine is overheated or not.

 

A download after failure would provide VERY valuable information

 

 

[motzartmerv]

We had full EMS logging on a 3300 (230) that went supernova on takeoff. Highest recorded temp during the event was 210 deg's, and two valve seats fell out. Factory said the valve seats wont fall out below 250. Either the factory have the numbers wrong or the EMS did.

 

 

[motzartmerv]

This has been my contention for some time. I dont believe the numbers in the operating handbooks etc are correct. 180 deg's (CHT) for up to 5 minutes, with a max limit of 200. So I could technically run my engine at 179 deg's all day? Unfortunately, I can prove this doesnt work.

 

 

[dazza 38]

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

I am glad that they have done the above, that is half the problem solved.

 

 

[jetjr]

Merv, good info, what caused the overheat?

 

I think too often we hear, engine broke through bolt/ valve broke/etc etc....end of story.

 

Need to know what happened first, ie did it overheat the cylinder, did egt jump up, had the cylinder been running 179 deg for hundred hours?

 

Did anyone dowmload the EMS after the event?

 

 

[Dafydd Llewellyn]

This has been my contention for some time. I dont believe the numbers in the operating handbooks etc are correct. 180 deg's (CHT) for up to 5 minutes, with a max limit of 200. So I could technically run my engine at 179 deg's all day? Unfortunately, I can prove this doesnt work.

Merv, I'm not arguing with you. In due course I'll get a 3300 into the test cell (may have to put a larger cooling fan in, to cool it) and then I may get some numbers that could help. None of the 3300 - engined aircraft is Type Certificated, and I have my doubts about its cooling system - but no hard data as yet. We'll get to it, but Ian's four-cylinder comes first.

 

 

[Dafydd Llewellyn]

I am glad that they have done the above, that is half the problem solved.

Well, side-stepped, anyway. Checking the valve clearances is a useful guide to the health of the cylinder head, in any case.

 

 

[turboplanner]

We had full EMS logging on a 3300 (230) that went supernova on takeoff. Highest recorded temp during the event was 210 deg's, and two valve seats fell out. Factory said the valve seats wont fall out below 250. Either the factory have the numbers wrong or the EMS did.

Or a lot of people are barking up the one tree, when the cat's in another one entirely.

 

 

[motzartmerv]

Merv, good info, what caused the overheat?I think too often we hear, engine broke through bolt/ valve broke/etc etc....end of story.

Need to know what happened first, ie did it overheat the cylinder, did egt jump up, had the cylinder been running 179 deg for hundred hours?

 

Did anyone dowmload the EMS after the event?

Hey jet. yes im sure the owner / engineer would have the data downloaded. There was some contention after the engine was independently inspected. It showed evidence of over heating but the data didnt align with what was shown. From memory there was some strange bearing journal wear aswel in which the journal itself showed wear but the bearing case didnt? or something like that, im sure the owner / engineer will read this post and chime in if im wrong.

 

There was never a reason given for the sudden over temp, the engine would routinely get to 180 deg's on takeoff, even when flown contrary to POH and climbed at significantly higher IAS. But would cruise comfortably sub 140 deg's.

 

The over temp event was the only +200 event that was recorded.

 

I cant comment in any more detail, I only flew the thing!!..lol.. Perhaps the owner might share the engine report from the independent. engine assessor who looked into it. It was very interesting.

 

 

[Dafydd Llewellyn]

That's why one has to do proper tests. More than half the problem is eliminating the irrelevant possibilities. Guessing won't get you there, tho it can produce a starting point. The CAMit heads are made from a more thermally-stable alloy; that will help retain the valve seats - but the temperature range is always a factor.

 

 

[Oscar]

This has been my contention for some time. I dont believe the numbers in the operating handbooks etc are correct. 180 deg's (CHT) for up to 5 minutes, with a max limit of 200. So I could technically run my engine at 179 deg's all day? Unfortunately, I can prove this doesnt work.

Merv - let me meet you half-way here, in the spirit of trying to exchange useful information rather than us beating each other over the head with our opposing prejudices (yes, mine as well as yours).

 

The POH has to be derived from the certification tests /compliance with the ASTM standards. The certification tests are done under very tightly-controlled conditions to a specified regime, using calibrated instruments.

 

Real-time flying in a real aircraft is NOT a controlled condition, the range of variables in real life includes the accuracy of the temp. reporting instruments, the run conditions, the quality of petrol, the engine power load and cooling performance profile etc.

 

Please note: I am NOT disputing that Jab. engines are too susceptible to out-of-condition damage. I absolutely accept that the margin for error is very thin indeed; what CAMit is doing (in part) is to improve that margin for error to something that will work reliably in the real world. The figures developed in this thread show that the actual incidence of failure for Jab engines is nothing like the inflated claims of some - but it is certainly sufficiently high that the work CAMit is doing is justified.

 

You were sitting in the right-hand seat of a 3300-engined Jab where one pot went nuclear, in circumstances that can only be attributed to detonation. That engine - under inspection by a reputable insurance assessor and NOT Jabiru itself (as imputed by the engine owner in another thread) had indisputable evidence of operation well out of limits. The Insurance Assessor's report confirms this. The engine owner did NOT provide either the engine logbooks OR the EMS recorded history to the investigation of that engine failure. The determination of relevant facts was redacted from the thread on this site but remains on PPruNe, and since you were a significant contributor to that discussion , I feel sure you will remember it. The physical evidence of that engine demonstrates that the claims of the owner are (mostly, at least) false.

 

If the 'safe' operating conditions defined in the POH are not being observed - not wilfully, but due to inaccuracies/inadequacies of the actual engine installation - then it is not the POH that is wrong, but the information that the PIC is using that is being reported to her/him falsely. There is, I believe, a valid argument here that audit of an installation using calibrated equipment is pretty much a pre-requisite for the assumption that one can just use the figures showing on the instruments in the cockpit to be sure one is flying within the limits of the engine.

 

 

[motzartmerv]

Thats right, i remember going through this on Prune ( never a good experience).

 

Like I said, the engine showed signs of over temping that didnt align with the data from the EMS. I wouldn't say that the owners claims were false simply because he didnt provide logbooks etc. Thats a bit of a call, and I can understand his reluctance to furnish jab with anything as it was clear they were only looking for an 'out'.

 

The same guy had emails from Sue claiming she couldnt legally return his heads to him (from another engine) due to some CASA mandate that he proved to be a complete fabrication.

 

The facts remain, the engine grenaded, for some unknown reason and showed significant over temp issues that didnt align with cockpit indications.

 

Like I said originally, either the numbers were wrong or the instrument wasnt reading correctly, which only shows how it got away, but not the cause.

 

I stand by my comments and assertions, I dont think these engines can be expected to survive when operated IAW manufacturers specs. 180 deg's is just to bloody hot!!!

 

 

[fly_tornado]

Rod Stiff is a crafty old bugger, I wouldn't trust him with an engine

 

 

[motzartmerv]

We went down the rabbit hole once before this incident with oil temp indications in a different 3300 (230)

 

An engineer ended up using a thermocouple down in the oil dipstick gallery to get a true oil temp reading. It ended up slightly hystereses, but within 3 or 4 degrees at operating temp. Mind you this was NOT in the engine mentioned above. But it confirmed the fears, the oil was indeed, too bloody hot!!!!. It was in spec, but bloody hot.

 

The instruments were Dynon EMS and factory installed.

 

 

[rick-p]

David I love the old Gypsy Major, truly a legend. I owned a J1N for about 14 years until it got rolled up into a ball by a freak wind storm. It broke my heart because it had history and was a great performer with the Mk 10 motor. It's first owner was Dunlop Rubber Co Australia. I think that I was the fourth owner in time. For all intents and purposes they were amongst the most reliable engines ever manufactured. At one time, just about every aircraft flying had one in one form or another. Now I'm only left with memories and a number of engine spares for a Gypsy 1 and other bits and pieces as I eventually sold the wreck.

 

 

[Oscar]

Thats right, i remember going through this on Prune ( never a good experience).Like I said, the engine showed signs of over temping that didnt align with the data from the EMS. I wouldn't say that the owners claims were false simply because he didnt provide logbooks etc. Thats a bit of a call, and I can understand his reluctance to furnish jab with anything as it was clear they were only looking for an 'out'.

The same guy had emails from Sue claiming she couldnt legally return his heads to him (from another engine) due to some CASA mandate that he proved to be a complete fabrication.

 

The facts remain, the engine grenaded, for some unknown reason and showed significant over temp issues that didnt align with cockpit indications.

 

Like I said originally, either the numbers were wrong or the instrument wasnt reading correctly, which only shows how it got away, but not the cause.

 

I stand by my comments and assertions, I dont think these engines can be expected to survive when operated IAW manufacturers specs. 180 deg's is just to bloody hot!!!

Merv, - (and I'm not looking to get into one of our infamous spats, we're both probably too involved in other things to be able to enjoy that any more) - but think about your statement that: 'The facts remain, the engine grenaded, for some unknown reason and showed significant over temp issues that didn't align with cockpit indications.' Physical evidence of things like oil boiling and charring on heads and barrels is evidence of physical limits being exceeded - the damn laws of physics don't change because of the recording apparatus. If it comes to a debate on whether the laws of physics are right vs. the record on the instrument - you are going to get 100% of qualified physicists coming out on the side of the Laws of Physics.

 

Yep, I agree - 'either the numbers were wrong, or the instrument wasn't reading correctly which only shows how it got away, but not the cause.'. And that's - seriously - a key point that we've debated here. What we NEED to know is the cause - and that requires expert investigation. Why did this happen this time? That's the key to determination of the cause of failures, and it adds nothing at all for one side to blindly suggest that it is all 'the engine's fault', as it does the alternative side to assert 'it's all the operator's fault'.

 

We can get beyond this 'tribal warfare' situation if we cooperate to assemble critical information. As radical as it may seem, I believe that RAA ambit aviation operation can actually progress considerably if we can all accept that Jab and Rotax (or other)-powered aircraft both have a role to play. The alternative seems to me to be cutting off one's nose to spite one's face.

 

 

[turboplanner]

I stand by my comments and assertions, I dont think these engines can be expected to survive when operated IAW manufacturers specs. 180 deg's is just to bloody hot!!!

Motz what's at 180 = CHT or Oil? and is that 180 F or 180 C?

 

The Chev 350 operating standard oil temp for highway running is about 115 deg C

 

Equipment using Synthetic oil quite often operates at 120 degrees C

 

Race engines often operate at 140 degrees C

 

Engine Management systems on some cars start to reduce power at 150 degrees C