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Another engine failure


Thirsty
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Hey guys,

 

Had my second Jabiru (2200) engine failure yesterday. Was taking a TIF and on climbout at about 1500' the engine went bang, bang, bang so I pulled the throttle to idle and before I could turn the mags off the prop stopped dead.

 

I set up to land in a field and another instructor (CFI) flying at the time suggested I turn back to the field and land downwind. I hadn't thought of that 'cause I'm used to flying a J160 which probably wouldn't have made it back and this was in a J170. So I turn back and misjudge it, land about halfway down the strip (1.1k long) at 80knots indicated and managed to stop well before the end of the strip.

 

Don't know what the issue was at this stage but felt very much like my last one which was an exhaust valve failure.

 

Aircraft and engines are well maintained by a very experienced engineer but flown by students so who really knows what it's gone through.

 

Will post back when I have more info on the failure.

 

 

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Hey guys,Had my second Jabiru (2200) engine failure yesterday. Was taking a TIF and on climbout at about 1500' the engine went bang, bang, bang so I pulled the throttle to idle and before I could turn the mags off the prop stopped dead.

 

I set up to land in a field and another instructor (CFI) flying at the time suggested I turn back to the field and land downwind. I hadn't thought of that 'cause I'm used to flying a J160 which probably wouldn't have made it back and this was in a J170. So I turn back and misjudge it, land about halfway down the strip (1.1k long) at 80knots indicated and managed to stop well before the end of the strip.

 

Don't know what the issue was at this stage but felt very much like my last one which was an exhaust valve failure.

 

Aircraft and engines are well maintained by a very experienced engineer but flown by students so who really knows what it's gone through.

 

Will post back when I have more info on the failure.

Not 5246????

 

 

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Aircraft and engines are well maintained by a very experienced engineer

i guarantee Jabiru will say otherwise..

 

On a more positive note, good to hear you made it down safely, and fingers crossed, the TIF student will understand the situation and not be afraid of light aircraft for the rest of their lives..

 

 

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If you guys need some guidance from Folk's in the know...you need just wip over the hills to Gawler who according to Jabiru clearly know how to maintain J engines......The J website says

 

"Adelaide Soaring Club& Lilydale Flying School both recently traded in engines +1000 hrs tt. Keep up the good engine maintenance .....As the saying goes....Good and proper engine maintenance is the key to engine life!!!!"

 

 

Things and folks must have changed since I was a member there and the site of an upside down J with YAEF induced flip on landing was not considered a rare thing.....

 

Andy

 

 

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Thanks guys. Still don't know what the issue was. The local expert is going to strip the engine and report but it looks like the engine is toast. The prop was damaged beyond repair too apparently. I'll post back once I know something.

 

The student was fine though admitted to being a bit nervous after we'd landed safely. She went straight back up in the schools 160 and was fine about it all.

 

 

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Thirsty

 

Glad to see it all ended well and the student was happy to get back on the horse (you were obviously on top of the game early, better to land half way down and not 100 m short, don't be too hard on yourself, also glad to hear you were happy to listen to someone else in the air at the time) .

 

To all you clowns out there who think just because you have a Rotax or any other engine for that matter that it will keep running keep your heads planted firmly up your backsides until the unthinkable happens then see what happens.

 

All engines can fail, Jabiru just happen to have more engines out in the market place than many others, in ultralights, so you would expect to see more Jabiru engine failures associated with the statistics. I personally know of several engine failures with other engines that have never been reported (I wonder how often this happens) so the stats end up skewed.

 

I agree Jabiru engines require good engine management but I fly every aeroplane with the same mindset, try flying some of the supercharged and turbo charged Lycomings & Continentals without the correct engine management and see where you end up.

 

 

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already had one engine out in my 582 through my own fault. Doesn't seem to happen as often as j.... though.

Do you fly your 582 as much as the Jabirus that do heavy duty at the schools. At my strip of choice, The Oaks, near Sydney, EACH of the Jabirus would be putting in at least twice the hours of any of the others there.

 

 

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To all you clowns out there who think just because you have a Rotax or any other engine for that matter that it will keep running keep your heads planted firmly up your backsides until the unthinkable happens then see what happens.

The statistics are unarguable, and certainly do not support Rotax owners and users as being clowns with the possible exception that of the few engine failures, where almost all can be traced to an obvious maintenance error.

 

These engine threads seem to be treated like a football match, with extremist spectators squawking from the sidelines, but the statistics indicate its more like Russian Roulette with the eventual likelihood of a fatal when someone fails to pull off the forced landing.

 

What is needed is someone with balls to step in and do something to protect lives.

 

 

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Do you fly your 582 as much as the Jabirus that do heavy duty at the schools. At my strip of choice, The Oaks, near Sydney, EACH of the Jabirus would be putting in at least twice the hours of any of the others there.

nope

 

 

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The statistics are unarguable, and certainly do not support Rotax owners and users as being clowns with the possible exception that of the few engine failures, where almost all can be traced to an obvious maintenance error.These engine threads seem to be treated like a football match, with extremist spectators squawking from the sidelines, but the statistics indicate its more like Russian Roulette with the eventual likelihood of a fatal when someone fails to pull off the forced landing.

 

What is needed is someone with balls to step in and do something to protect lives.

I never said Rotax owners were clowns, that is just your interpretation of what I said (go back and read the post), you HSE people are the same the world over as long as it suits your spreadsheets, TRIFR, LTI, hazards vs incidents vs LTI's vs fatalities you're happy, any idiot can make a spreadsheet say what you want it to say, what is actually required is that you present apples vs apples which never happens. In this case Jabiru engine hours vs all other types engine hrs (the apples being engine hrs) and as long as all are reported then you are able to get an accurate picture, until that happens all you get is people assuming (in this case) Jabiru engines are no good which is not an accurate assumption.

 

What would be interesting is to know how many lives have been lost to Jabiru aircraft compared to other types.

 

 

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To all you clowns out there who think just because you have a Rotax or any other engine for that matter that it will keep running keep your heads planted firmly up your backsides until the unthinkable happens then see what happens.

I'm happy to just quote your post Aldo; I'm not quite sure what an HSE person is.

 

 

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It doesn't matter what label is up front, if you're flying around in a single and NOT expecting the sound to go out at any given moment, you're an idiot. I happily fly in a Jabiru knowing that if the sound went out, I'd be confident getting it down safely. Flying with a lycoming or rotax up front wouldn't change my attitude. Your engine may be more reliable than mine, but your false sense of security is by far more dangerous.

 

 

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Every time a Jab engine stopping in flight is mentioned on a thread, that thread turns into a tribal fighting ground. In most - but thankfully not all - cases, the end result adds sod-all to helping us gain real understanding of the causes of the stopping.

 

The original post was a very good one - it bought out several important points: firstly, that by good airmanship and decision making, an in-flight incident did NOT become an accident with injuries or worse to the people involved. Great work on the part of all involved.

 

Secondly, that it is recognised that the actual use pattern of the engine is unknown and is (likely, at least) to be at the minimum a part of the 'story' of why this engine ceased to run. As usual, we have a mix of possible causes, and despite the positions that 'opposing' sides typically take (in this case, Jabiru more than likely saying it is down to operation and others saying it is down to poor design / components), the answer is extremely likely to be an interaction of both elements.

 

That Jab. engines - particularly 2200s - have more in-flight stopping than is reasonable, is unarguable. That there are a range of improvements that can be made to make them more robust is not just obvious but is the basis of the business case for the CAMit and Rotec developments. However, a powerplant's mechanical performance is only part of a 'system' of propulsion that includes not just the bits of metal (and wood) whizzing around but the cooling, fuel and factors of operation. A serious 'out of expected condition' for which the engine was designed can cause a stopping event - and not all of those could reasonably be deemed to be a 'failure' i.e.: Failure is the state or condition of not meeting a desirable or intended objective. If the limits of the objective have been defined and those limits are exceeded, then the engine stopping is a consequence - not a failure.

 

This is not just petty semantics; we accept the existence of standards for just about every aspect of our lives. For example: car brakes have limits of effectiveness in retarding velocity. If crash avoidance requires that the brakes would have to exceed their design parameters, hitting something isn't a 'brake failure' provided they have performed as designed.

 

If we try to look at the situation of Jabiru engine stoppages objectively it is apparent that they need a closely-controlled operating environment. The most critical of these factors is effective cooling in all operational conditions. It's fair comment to suggest that this is an area with a high potential for problems in the case of Jab. engines: a quick wander through the 'Jab. Cooling' thread: http://www.recreationalflying.com/threads/jabiru-engine-cooling.112581/ will show just how tricky it can be to get it right. That's a recognised fact in the industry: Lycoming audit factory installations and won't provide a warranty unless you get their company 'tick' of approval - and of course, G.A. installations do not allow ANY little tinkering under the cowl that isn't tested and approved.

 

A major impediment to the objective development of useful analysis of Jabiru engine stoppages has been the lack of any effective monitoring and recording (in too many cases) of operation. A single cht and egt reporting set-up is quite simply only marginally more useful than nothing - and in most cases, we know that the standard cht probe on a Jab. engine is often placed in the worst position for reporting the peak cht, which tends to wander around amongst pots anyway depending on airspeed and engine load. Both cooling duct performance and fuel distribution affect this, and it's London to a brick that there are a considerable number of operators who have watched their gauges assiduously without being able to tell that a different pot to the one being monitored was cooking itself. You can't be expected to know what is happening to your engine if there is nothing telling you! Those of us old enough to remember when cars changed over from oil pressure gauges to warning lights will remember the old mantra: the oil-pressure warning light is there to tell you that something ugly HAS happened, while the gauge used to tell you that it is on the way to happening..

 

If I were a commercial operator of a Jabiru engine, I'd absolutely install a full set of gauges feeding into an EMIS with a recording facility. The cost of that vs. the cost of a full rebuild at way less than the expected TBO is a no-brainer - and that of course isn't taking into account any cost for a forced landing and resulting damage to the airframe over and above the engine re-build cost.

 

Thanks to Thirsty, we will hopefully get a full report on the findings of the strip-down, which may provide some clues as to the exact condition of the 'broken' bit/s, from which likely cause/s can be deduced. If that engine had a full recorded history of cht's and egt's, it's easy to see how much more additional information would be available to really track down the cause/s.

 

 

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TBO doesn't mean the engine makes that figure without work being done. " Tops" are done on many engines and the odd cylinder may be removed and something "fixed" from time to time. That is why you do you check compressions often By feel all the time,and at 100 hours or some periodic situation A rough check of valve guide wear can be done but who does it? I would and do. Nev

 

 

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I am not a mechanic so take this for what it is worth which is a comment on my (as well as qualified and experienced others) view on how to possibly improve the engine situation in a positive and productive way. It is such a sensitive area for Jabiru owners and all the knockers but one that needs careful and proper analytical evidenced consideration.

 

Is there something wrong with the way the Jabiru engines are being operated which is exasperating the premature failure of the engines?

 

Engine cooling may be one area but another problem is possibly the fuel used. Having read about and personally seen a number of Jabiru engine problems both in flight and picked up during preflight/maintenance there is a view that lead fouling from Avgas is leading to deposits forming on spark plugs and valves. Due to the fine tolerances of the Jabiru engines one of the problems is that these build ups are causing exhaust valve leakage leading to the burning of the valve head and stem eventually resulting in the valve breaking free into the cylinder impacting with the piston leading to a full engine failure. This seems to be a particular problem occurring in the 300-700 hour range. This is one but by all means not the only answer to premature engine failure.

 

Lead Fouling

 

Lead (TEL - Tetra Ethyl Lead) is added to Avgas to act as an octane booster to prevent preignition in high compression engines - btw the level of lead is about 5 times what was in the old leaded auto fuels. The problem with leaded fuels is that they will leave lead oxide deposits in the engine if not fully burnt off. To assist, Ethylene Dibromide is added to the fuel to react with the lead oxide to become the more volatile Lead Bromide, a gas at 200-250 oC but it goes back to a solid as the exhaust gas cools. A high combustion temperature is required to ensure that this reaction works without leaving large amounts of buildup in the cylinder heads. Higher cylinder temperature also helps the rings to seal properly, limiting acid and lead by-products going into the sump oil leading to long term corrosion problems. (Jabiru moved to 25hr oil changes to prevent problems as a result of lead contamination of the sump oil.)

 

If the engine is run at idle such as during warm up, taxiing and landing and the engine is shut down cool after a long taxi then there will be significant fouling especially around the spark plugs and exhaust valves. To make the problem worse, if the carburettor can not be set to run lean during idle then a higher fuel mix, then what is needed, will be fed into the combustion chamber making the temperature problem worse.

 

Of particular note there was a large number of problems recently that affected all light aircraft resulting in major fouling of plugs resulting in replacement on the Cessna’s etc used for training at a major airfield due to what was thought to be a higher lead concentration in the Avgas used (but still in specification) so not just a Jabiru problem.

 

Jabiru and other recreational sport engines are not high compression and don’t need the high octane fuels. The bing carburettor also can not be leaned. Jabiru engines support both Avgas and premium mogas but Jabiru recommend Avgas in preference identifying the knock resistance, availability at airports and the quality control whilst noting the lead fouling issue in the combustion chamber.

 

Possible Solution (for some of the problems)

 

Run unleaded fuel.

 

At a location with high Jabiru hour usage, after a series of problems and following LAME advice, there have not been these problems experienced with the engines by switching to unleaded premium mogas fuels. If the heads are already fouled then switching to unleaded is not going to fix the damage already caused (and may even be making it worse due to the decrease in compression pressure resulting from leaky exhaust valves).

 

Some engines seem to be fine running on Avgas and are getting long hours without problem but maybe due to them running at full power (hotter) for longer and less time idling they are not getting the buildup of lead around the valves.

 

Preflight Inspection

 

It has been recommended that whilst pulling the engine through before the first flight that in addition to feeling for poor compression and listening for mechanical noises you should also be listening at the exhaust for air escaping through the exhaust valves on compression. If you hear puffs of air escaping then further investigation of the exhaust valves is needed suspecting inadequate exhaust valve sealing and imminent problems. It was also suggested that the Jabiru engines normally run very well balanced and if they start to feel rough then it is worth investigating further.

 

Full engine monitoring

 

Full engine monitoring will pick up the exhaust valve leakage due to a rise in EGT identifying the need to pull the heads off to inspect. So maybe that is something we all should look at.

 

One thing is certain though - if the problem is not identified and fixed then the engine will fail.

 

I am experiencing this problem personally because my Jabiru is currently having the heads cleaned up and the exhaust valves replaced after 300 hours running mostly Avgas with a high level of idle taxi time and landings due to the nature of the aircraft usage and the airfield/s it is operated from. Luckily for me the problem was picked up during a 100 hr service so I did not have to worry about finding a nice spot to land…

 

I do believe the engines are okay but that the recommended fuels for these engines should be investigated further and recommendations potentially modified. But for me, until there is easy access to unleaded Avgas, I am going to be only running on premium unleaded mogas to prevent lead fouling problems and eliminate contamination of the sump oil.

 

 

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Valves having angled seats tend to centre and seal reasonably at slow revs or a static test, but are subject to bending loads in a running situation. Triumph TR's with 4 cyl. vanguard motor and Volkswagens suffer valve breakages with guide wear. (as they are short in the stems).

 

To check you have to use a dial gauge and have the rocker JUST lifting the valve off the seat. Push the valve collet holder at right angles to the rocker shafts and check the amount of movement in the dial gauge and factor allowing for the length of stem protruding About 2/3rds is close so if it should .006", it would be about .004" (4 thou.) They normally wear oval so check the play at 90 degrees and compare. You can only get a good accurate figure with the head off and the valves out, and measure both components (Measuring valve guide bore size requires skill and practice) . But the rough indication will pick up something that is going to give you trouble.

 

Note .. It is very important on this type of motor to get the valve to rocker geometry correct or valve guide wear will be excessive. Rocker bush wear should be checked also. I think some of the earlier motors had some coating on the bushes. Nev

 

 

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