Jabiru Engine Reliabiity - The Way Forward?

[Anonymous]

Posted by: BobP on 22:51:08 12/05/14 Fri

Its pretty clear from Jabiru Australia comments on the CASA engine reliability concerns that they do not have a clue as to the reliability issues that the engine has, and more particularly as to which modification states/engine serial numbers have particular reliability issues. I have always believed that the Jabiru engine design is good but that certain ranges of engines have adverse reliability due to a few original weak points; the introduction of ill-thought design "improvements"; or because of the use of batches of defective/substandard components.

No doubt LAA will at some time take an interest in Jabiru reliability issues and, in the absence of definitive reliability information being available elsewhere I wondered whether we (all UK Jabiru owners) might be able to work with LAA to determine which groups of engines have particular reliability issues, and then go on to determine an appropriate inspection/upgrade regime for those engines to minimize the risk of in-flight failure / improve reliability. It seems to me that if the known (but never admitted to by Jabiru) problems were to be addressed, the underlying reliability (and credibility) of the engine would be re-established.

So my proposal is that a group of us with particular expertise/experience should get together and produce a detailed survey questionnaire. The questionnaire would then be reviewed and agreed with LAA and then circulated (via LAA if possible ) to all UK Jabiru engine owners.

By collating the results of the survey it should be possible to identify whether/what additional checks/modifications are appropriate to which engine groups, rather than draconian rework instructions being imposed from "above" in a knee jerk reaction. Innapropriate global edicts might be totally ineffective/inappropriate and even reduce rather than improve the reliability of some groups of engines.

For example my gut feel ( although a detailed survey could well prove me to be wrong) is that:

1) Aircraft fitted with wooden propellers and which have never had any prop-strike have a very low risk of flywheels falling off.
2) Loctite on flywheel bolts may be counter-productive
3) The batch of engines with grossly over-bored valve guides account for the majority of valve failures
4) Engines supplied before the batch with defective undersized through bolts carry minimal risk of through bolt failure, and so the risks associated with their replacement (breaking of the seal between crankcase halves and risk of subsequent oil pressure loss and/or fretting) would decrease rather than increase reliability.
5) Requiring the CHT sensor thermocouple to be in the head (rather than on a tag in the breeze) so true head temperature is measured and a meaningful maximum CHT can be defined (rather than some arbitrary measurement dependent on the exact location and trimming of the baffles (different for every engine ever installed)).
6) Requiring the oil pressure gauge to be located in the gallery to measure true oil pressure (with new limits defined).
7) Engines with the original economy jetting may be more prone to early failure.

Please post your thoughts on the above (for and against). If you would be interested in helping to develop a questionnaire please contact me at jabiru(curlyAsymbol]panth dotCOdotUk

[Anonymous]

Posted by: Geoff Roe on 16:59:43 12/03/14 Wed

Good idea, Bob. I've suggested something similar to LAA and CASA. We need to define the major risk areas (presumably through bolts, valves, flywheel screws) to try to understand the failure mechanisms (difficult as opinions vary: CAMit input required here) and thus to establish which S/Ns are at risk and what solutions should be adopted. These could range from operational limitations through special maintenace/ inspections to modifications if really unavoidable.

This is of course exactly what CASA,RAA,Jabiru and CAMit should be doing to restore confidence in the engine and to establish a reliability improvement programme, with milestones. This should enable CASA (Jabiru cooperation permitting, and with their past record this is certainly not guaranteed ) to remove their current threat of draconian operational restrictions, and so take the heat out of a situation which could still easily spiral out of control.

All this will be highly controversial but I agree it would be good for UK to take a lead, winding in others If we can make enough progress here. I'm happy to participate based on 8 years/600 hours with an early HL ( yuk) 2200 which hasn't yet let me down but has required a lot of tlc. My contact details are geoffatgeroedotplusdotcharlieoscarmike.

PS. I've been struggling for months to make progress with LAA on approval of CAMit improvements, including HL to SL conversion .

[Anonymous]

Posted by: northumbrian on 22:24:00 12/03/14 Wed

I agree completely with bob p and geof. We have to get on with the job. If Jabiru don't want to sort the problems out then Jabiru owners will have to do it.
Sorry if this makes anyone "lol"
Brian.

[Anonymous]

Posted by: Matt on 23:05:40 12/03/14 Wed

Not sure what your trying to achieve here guys. So far there are no mandatory permit directives for the engine and no mandatory mods. If you phone the LAA and talk to Malcolm mcbride I think you'll find he's fully aware of the problems surrounding jabiru engines. You'll also probably find he's also been in contact with jab aus. Ultimately being the owner operator we are liable for the continued airworthiness of our aircraft and as such are able to perform the required modifications as we see fit. Now with Camit able to supply part there should be some better quality parts available. Also by tailoring our maintaince schedules and being proactive with hard time replacement of items such as flywheel bolts, rotor arms then we can improve fleet reliability.
If your really concerned phone the laa and get there input first

[Anonymous]

Posted by: Steve on 09:03:52 12/04/14 Thu

The biggest problem with the issues is that the majority are never reported so no organisation really has a definitive list. The LAA, I know, are aware of some of the common issues of the Jab engine but they certainly would not be aware of the scale of them (if at all there is a large scale).

All the work I have had done to my engine has never been reported anywhere. The cracks between the cylinder heads, a broken flywheel bolt are not on the statistics as I just repaired them at my cost.

I think in the early days, the problems were reported and Jabiru chose not to act. Now a lot of owners don't report the issues as they don't see the point and they just get on and repair them.

It may be the case that the scale of the issues is just hearsay but there is no way this will ever be found out unless every single owner is questioned regarding the work and problems that they have experienced on their engine.

This could all be exaggerated and the comments are just based on the early reputation of the engine but the fact is that no one knows.

[Anonymous]

Posted by: Geoff Roe on 09:24:34 12/04/14 Thu

I saw Bob's initiative as an attempt to gather some useful data on UK experience. This would replace the anecdotal stuff and could just possibly shine some light on the different problems. I remain willing to contribute. In an ideal world the LAA would lead on this, but they don't have the resources. We can certainly seek their views, but i'd be amazed if they weren't keen on the idea. It will of course require a fair amount of effort if we're to do it properly.

I believe we could gain from sharing our knowledge. Given the high rate of change in Jabiru's design we are operating many different standards of engine in a range of installations (mine's a small Jodel) and with very poor support from the designer/ manufacturer, some of whose ideas (eg JSB 031) are bizarre. Using this as an example, some of us have done the Loctite mod (not me) and others haven't. It's not covered by an MPD, so anything goes. Some have had specific advice on this from the LAA, and others not. Which particular engines are most at risk? If the problem is partly down to substantard threads on some bolts which s/ns were involved? Not a happy situation, any of it.

I entirely agree about CAMit, but we have yet to to gain LAA approval to exploit their work. This won't have bothered some people who will have done so anyway. It would be good to know what they think.

So I'm prepared to help Bob and others to analyse our collective experience, but only of course if most would find this useful. If not we can simply go back to doing our own thing, but I personally think this would be an opportunity missed.

If we do go ahead (and the jury is clearly still out on this) we'll need a private email group to include all participants.

[Anonymous]

[Anonymous]

Posted by: Matt on 17:33:47 12/04/14 Thu

I would say that identifying problems by serial number would be very beneficial. That data would enable the the operator to plan modifications and maintenance accordingly.
If CASA decided to issue an airworthiness directive I think firstly it would be primarily for aircraft used for flight training, so won't affect us. Just like all these so called "mods" we have now. If they did issue an AD covering all engines then the UK CAA would likely adopt it and neither we or the LAA would have a say. So would be grounded. Any results from the survey would help in a business case in that the LAA would have to put the CAA to remove any draconian measures.
I talked to Malcolm earlier this year. He was in contact with Jabiru regarding their attitude to supporting their products but there is very little he can do. For this exercise to be anything more than a survey then we will need the support of Malcolm and the LAA

[Anonymous]

Posted by: Gary on 18:51:31 12/04/14 Thu

Think you need the support of Skycraft also, they would have a good idea on uk issues going by what items of stock they have been selling. Has anyone approached Skycraft regarding the latest issues?

[Anonymous]

Posted by: Matt on 22:51:08 12/05/14 Fri

http://contrails.free.fr/engine.php. In French but if you click on the Union Jack the articles are in English. Interesting one of flywheel bolts