Yet another Jab down.....

[Phil Perry]

Can someone tell me if the aircraft in the attached picture uses Jabiru Engines please,. . . . a friend picked this up from an Australian site ( I think ) or is it just a concept mock-up. . . . . . ?

 

Just interested to know.

 

Phil

 

 

 

[facthunter]

Early rotate is a problem anytime with that type of aircraft. Might be pilot technique and training needing attention. Your rotate speed has to be calculated for every take-off and the rate of rotation should be correct too. The aircraft might be more critical than most. Non bypass engines don't have a lot of thrust to spare..

 

Reply to above

 

Phil I believe they are Jabiru...Nev

 

 

[dutchroll]

No doubt all correct but Dr comment is not adding to discussion.What exactly can be forced on Jabiru?

 

Continued innuendo also doesnt add to the topic

Regulatory action. My understanding is that this is a large blip on CASA's radar at the moment.

 

 

[facthunter]

Wisdom from above. Everything will be OK now. Sure.... While some might see this as good ,it might be not good for the whole movement in the final outcome. Nev

 

 

[ayavner]

Interestingly enough, in this month's Sport Pilot, p 31, there was an article about an Engine failure survey: Of note:

 

* of 3200 aircraft registered with RAAus, 429 responded to the survey.

 

* of those 429, 1/3 were Jabs, 1/3 were Rotax 4 strokes, and the rest were lycomings, 2 strokes, VW, etc.

 

* of those, 1/5th (or about 100) experienced an engine failure - most jabs being for thru bolt, piston/ring, exhaust valve and most rotax for sprag clutch issues, CDI or electronic ignition failures, or gearbox problems.

 

The survey is still open as far as I know, and full analysis and results aren't available.

 

Maybe concerned parties (or everyone really) should take the survey to help build an accurate picture?

 

Of course, in typical style, they say "information is available on the RA-Aus website", which buggered if i can find it. And they provide a link which contains roughly eleventy-billion random numbers and letters in the hyperlink - ever heard of tinyurl, guys??

 

 

[Old Koreelah]

Can someone tell me if the aircraft in the attached picture uses Jabiru Engines please,. . . . a friend picked this up from an Australian site ( I think ) or is it just a concept mock-up. . . . . . ?Just interested to know.

Phil

Yep. I believe Jabiru South Africa designed and built this aircraft. Innovative way to keep thrust lines as close as possible. They're a go-ahead mob; it was claimed there are more Jabs flying in SA than Cessnas.

 

 

[Phil Perry]

Early rotate is a problem anytime with that type of aircraft. Might be pilot technique and training needing attention. Your rotate speed has to be calculated for every take-off and the rate of rotation should be correct too. The aircraft might be more critical than most. Non bypass engines don't have a lot of thrust to spare..Reply to above

Phil I believe they are Jabiru...Nev

Thanks Nev, . . . . . . regrettably, the commander on one of the Comet "overruns" was a highly experienced pilot who had helped in the development of the type,. . . .everyone makes errors I guess.

 

And thanks for the heads up on the Hot twin glass aircraft, it looks delicious, I wonder if it is a production machine or a concept prototype, never seen one before.

 

Incidentally,. . .and just to stay on message, . . .a friend of mine has been asking people on the BMAA site here in the UK about the Jabiru aircraft, as he is thinking of buying one. I suggested that he connects with this site, and then he can "Read all about it"so to speak.

 

And thanks to Old Koreelah as well. . . . . . .thanks Gents.

 

Phil

 

 

[biggles]

Can someone tell me if the aircraft in the attached picture uses Jabiru Engines please,. . . . a friend picked this up from an Australian site ( I think ) or is it just a concept mock-up. . . . . . ?Just interested to know.

Phil

Yes Phil , 4 cylinder Jab . engines in fact .

 

Bob

 

 

[Guest Maj Millard]

Wisdom from above. Everything will be OK now. Sure.... While some might see this as good ,it might be not good for the whole movement in the final outcome. Nev

Facto....If Jab fixed their engine mechanical probabily area we would have a general and noticeable reduction in accidents overall. Many of the Jab forced landings particularly in the SE Qld area have made a big national press footprint. As I'm sure you would agree this does nothing for the image of our sport or organization as a whole. It is true that Jab is firmly on the CASA radar , probabily 5-10 years too late in my opinion, obviously the aforementioned coverage of recent accidents has caught their eye also. Will be interesting to see how then new CASA administrator handle things.

 

 

[Phil Perry]

Yes Phil , 4 cylinder Jab . engines in fact .Bob

Thanks Bob. . . . . . .Y'Know,. . . . . you just can't ask the wrong thing here. . . . . .!

 

Phil

 

 

[facthunter]

POST DOES NOT ADD VALUE - MOD

 

 

[facthunter]

Maj, CASA have had a look in the past and the equivalent in NZ have too. I am unaware of any specific actions resulting. I don't see the current situation as good enough, but I wonder where in CASA the expertise would be coming from where they would do anything but impose limits to use or a general threat. They would be unlikely to recommend design changes of a specific nature. ( I wouldn't like to fly an engine, built to a CASA design). It's also probable that an engine would pass the tests required to be used in VH registered aircraft as a certified engine.

 

Which engine will you choose and if they both pass what then.? . I can't see how we would be better off if the Jabiru engines were grounded and there are plenty of other types of engines flying that are worse. ( I won't list them here for obvious reasons.)..

 

The fact is, many do get good service from their engines. In South Africa for example.( general statement of course) Some here have had a consistently bad run with their motors. I'm not inferring blame but I've consistently recommended to check compressions by hand propping and don't fly a motor that feels wrong on compression makes noises of a mechanical nature, vibrates or misfires. This applies to ALL engines we are likely to be involved with in our field of aviation. There's plenty of engines I would fly in historic aircraft that would be much worse than the Jabiru for reliability. ie Pobjoy, Salmson, Warner Scarab JAP. etc etc. plus many two strokes. Even the old gypsy major ain't what it used to be.. Nev

 

 

[Guest Maj Millard]

Nev, the list of engines you list at the end of your prev post rarely are used in our level of aircraft. The Jab engine accounts for a large percentage.

 

A lot of the compression loss you mention is cause by carbon build- up under the valve seats. As you no doubt know any infernal combustion engine can and will suffer from this.

 

It is especially prevelemt with 4 stroke aircraft engines for a number of reasons, even though we have the large advantage on some to be able to 'lean out' the mixture for a more efficient burn. Another reason is the lead content in Avgas which we often use, and is the recommended fuel for the Jab engines. Lead content when burned will foul the plugs and cause a build-up and compression seal leak on engine using it.

 

How then do most GA type engines ( Lycoming, Continental and others) deal with this. The contact angle on valves and valve seats can be critical to keeping a build up from valve seats. Additionally some engines are engineered so that the exhaust valve in particularly rotates slightly in operation thus clearing or 'cutting through. ' any potential buildup. Valve spring and actual contact tension on valve seat can be important and assist also. The actual speed or velocity of the gas flow through the exhaust valve seat area can also be a factor.

 

Rotax 912s can also loose a cylinder due to exhaust seat carbon build- up but usually occurrs well beyond TBO after several 1000s of hours of operation. Generally then a simple head removal and standard valve gring usually puts things back to as good as day one again. Most of the above has been common knowledge on internal combustion engine for decades now.

 

Can you tell me then, with all parameters and fuel being the same, why the Jab engine regularly incurr serious compression destroying carbon build up on their exhaust valves and seats, inonly as little as 200

 

hours of operation.

 

What has Jab NOT done to eliminateate this problem in the design of their engine..... ??...........

 

 

[facthunter]

I don't believe the heads will do huge hours without servicing. This has often been stated by the makers of the Jabiru engine. A gypsy major doesn't do high hours either without a "top".

 

Then we add the fact it is an auto valve and overheating is a common feature plus mixture "irregularities" and hydraulic lifters which by design or application I wouldn't use in a fit. Leakage at the head cylinder interface requires correct retensioning to ensure a seal is maintained..If the head has been overtemped by a significant amount it may be ruined for all intents and purposes, and require replacing. valve guides should be inspected for wear as that will promote valve stem breakage . Incorrect rocker geometry causes rapid wear of guides. Nev

 

 

[alf jessup]

Nev

 

But the maker of these fine quality certified engines boasts on his website a 2000hr TBO which is well and truly dreaming IMO

 

The lovers on here always sprout that there is over 6000 engines produced and the ratio of failures seems ok

 

Mr Bombardier has produced over 50000 912's with a far cry less failures or stoppages considering how many are out there world wide

 

Now that is something to gloat about

 

No 400hr head replacement, no thru bolt failures , no dropping valves and many seeing well beyond the recommended 2000hr TBO with just the normal maintenance

 

In this day and age you get what you pay for

 

At 13K for a J engine and 25K for a R engine I know which one is a bargin for consistency and longevity

 

I want to see the J survive but you can't blame the owners and maintainers all the time there is just as many R owners that would be as bad maintainers but the failure rate is less than a 1/3 rd with almost 10 times the number of engines more out there providing excellent service

 

Alf

 

 

[facthunter]

What you say is true Alf, But the motor and particularly the parts are multiples dearer. They usually do 2,000 hours easily but you visit the drive every 400 hours (from memory) and have a lot of hoses to look after. The stats quoted somewhere previously don't show the good results the older 80 HP motors did. The latest 914? seems to have a few problems also, being much more complex. The perfect aeroplane motor hasn't been made yet. Piston engines are not the most reliable thing in the aero environment, where light weight has to be achieved, and compact helps (frontal area). On the TBO question, If a motor had low time failures to the extent it was fairly common to not make TBO the figure would be brought back. Incidently TBO doesn't mean that you don't need to do anything on the motor till that time. Few engines make it without a "TOP", even today to TBO. Conditions of service vary too. An engine used infrequently won't do high hours and longer sectors usually don't tax the motor as much. The start warm up T/O and climb are the hardest on the motor. In cruise is it taking it a bit more easily at around 75% power. Nev

 

 

[dutchroll]

Even the old gypsy major ain't what it used to be.. Nev

It's 80 years old!

You won't be what you used to be when you're 80 either!

 

 

[alf jessup]

Nev,

 

Yes true in some respect, the gearbox needs an inspection at 600hrs but I am thinking that may have gone out to 800hrs now but don't quote me on it, and yes hoses to replace ect but that is a far cry from re ringing, new heads and valves not to mention thru bolts on average around 400 to 500 hrs, not many 912's ever have the heads touched in 2000hrs, you may get the odd one but nothing like we are seeing from a J engine, J has been around 20 odd years and so has Rotax (25 years) for the 912, one of them has got it right compared to the other in reliability stakes IMO and they have produced 45000 more engines with far less failures than we are seeing of late.

 

The aircraft itself I have no problem with, it is the mentality of the owner/factory blaming everyone else for their inadequacies I cannot stomach, I know for a fact that one of my friends when buying one on pickup had a few queries regarding the aircraft finish and the answer he got was do you want it or not, because if you don't someone else will buy it, now that is customer service hands down.

 

Yes some have had a good run out of them and plenty of others haven't and some have not had a pleasant experience from the factory either.

 

I for one would love nothing more than J to be a bit more robust, it would be the best valued aircraft in the world today except for what is powering it at the moment.

 

Yes wouldn't we all like a turbine in our organisation as far more reliable and also far more expensive in price and overhaul.

 

Alf

 

 

[jetjr]

How about this

 

Rotax is a good engine no one is sayong otherwise, go sit somewhere quiet and preach to yourselves

 

Its not Rotax vs Jabiru debate

 

The aircraft in this post and others could not have had anything different fitted so its irrelevant.

 

As always ends up being said, Jabiru have past cerification for some engines and there are thousands out theremany performing well. CASA isnt going to bring in new rules just for Jabiru but for ALL Raa aircraft

 

Im not sure about "all the publicity" been mentioned, small "cessna" does outlanding no one hurt, isnt big news. Other fatalities around the place are more worrying. Some of them even had the golden ring of confidence installed upfront, a 912

 

 

[facthunter]

Turbines,...They use too much fuel too,unless they are large and working at altitude. Nev

 

 

[dutchroll]

CASA isnt going to bring in new rules just for Jabiru but for ALL Raa aircraft

I wouldn't be wagering money on that. They'll look at the stats and if there is an outlier as far as reliability or failure modes, they could address that individual example through ADs or whatever else.

I suppose I shouldn't care. I have an M14P and provided you warm it up like a radial should be, it's as close to bulletproof as a piston aero engine can get. If it ever stops I'll know that I've run out of fuel.

 

 

[facthunter]

DR As well as being old they aren't done right in some cases. People want to modify things thinking they know a lot more than the original folks and sometimes they don't.. Old metal can age harden and fatigue is there from long use. I believe there is a time to replace an aero engine for the above reasons but we like to see these things flying and it is a great tribute to the patience and application of these people that some still fly, with original type engines fitted. I am particularly interested in the Rotaries. The REAL ones where the engine turns and the crank stays still. Gnome et Rhone etc. Some of the stuff was pretty ordinary when new actually, poor design and metallurgy, but what would you expect? It's old in concept too. Nev

 

 

[Guest Maj Millard]

I don't believe the heads will do huge hours without servicing. This has often been stated by the makers of the Jabiru engine. A gypsy major doesn't do high hours either without a "top".Then we add the fact it is an auto valve and overheating is a common feature plus mixture "irregularities" and hydraulic lifters which by design or application I wouldn't use in a fit. Leakage at the head cylinder interface requires correct retensioning to ensure a seal is maintained..If the head has been overtemped by a significant amount it may be ruined for all intents and purposes, and require replacing. valve guides should be inspected for wear as that will promote valve stem breakage . Incorrect rocker geometry causes rapid wear of guides. Nev

Nev, Rotax have metal to metal head sealing, hydraulic lifters, and normal valve guides...so tell me why does one make TBO and the other doesn't have a chance without major work ?..........

 

 

[Guest Maj Millard]

What you say is true Alf, But the motor and particularly the parts are multiples dearer. They usually do 2,000 hours easily but you visit the drive every 400 hours (from memory) and have a lot of hoses to look after. The stats quoted somewhere previously don't show the good results the older 80 HP motors did. The latest 914? seems to have a few problems also, being much more complex. The perfect aeroplane motor hasn't been made yet. Piston engines are not the most reliable thing in the aero environment, where light weight has to be achieved, and compact helps (frontal area). On the TBO question, If a motor had low time failures to the extent it was fairly common to not make TBO the figure would be brought back. Incidently TBO doesn't mean that you don't need to do anything on the motor till that time. Few engines make it without a "TOP", even today to TBO. Conditions of service vary too. An engine used infrequently won't do high hours and longer sectors usually don't tax the motor as much. The start warm up T/O and climb are the hardest on the motor. In cruise is it taking it a bit more easily at around 75% power. Nev

Non comprende senior' .....what are you saying Nev that Rotax 912 s spend more time cruising ?....hell isn 't that the idea !... Fact is there are just as many 912s out there used in the training arena with less failurers. 912's by the way will easily make stated TBO with out requiring a top overhaul, and I have seen many do just that , just as many other successfull aviation piston engines will also.

 

 

[facthunter]

Address the Jab problem with AD's or whatever else? Now I'm really worried. I would be IF I had a Jab. How would you or CASA pinpoint the problem with the Jab engines.? There are many different ones, and don't forget SOME get a good run out of them, so do the same AD's apply to the people who are not having problems?. If you impose costs you would want to make very sure you know what you are doing, if you want the respect and cooperation from the industry and not just continue to make life hard for the participants in the game. There are many instances where action has gone off half cocked in the past. Make sure you achieve a researched result. Not just act to look as if you are doing something. Nev