Yet another Jab down.....

[Guest Maj Millard]

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

I think CASA knows what the problems are, just like we do, and soon I feel that they will have to do something to protect their own butt...because that's all they really are good at anyway.......

 

 

[facthunter]

Maj I can't see that the different flight phases are relating to one engine or the other. It wasn't my intention to differentiate. It was a general statement of engine use.in an aircraft.

 

Lifters aren't lifters as oils aint oils. It depends on design and suitability. I know of ONE engine failure due to a lifter on a Rotax. It was on the way to a Natfly. Documented. It's a rare happening. I am not saying the Jab has lifter failure but I believe manual adjustment is better as you can keep tabs on the wear of valves and condition of seats by the changing of the settings, which you don't know about it if adjusts itself automatically . This view is that of Camit I believe.

 

The Rotax runs too cold generally and the Jab often runs too hot. That and the fact the Rotax heads are retained better and the heads are much more stable dimensionally. (More even temperature. They don't give much problems except lead if avgas used) You expect this with liquid cooling. Also the barrels are steel on the Jab and alloy on the Rotax. The alloy conducts heat much better..

 

Maj Just noticing your recent post. IF anyone knows for sure what is wrong why not let everyone know?. People might conjecture, but let's get specific here, as that's what is required. Not knowing where this is going is not good practice. There are people out there who should be informed IF something concrete is known. I remain sceptical that they do, actually. Nev

 

r

 

 

[Guest Maj Millard]

Maj I can't see that the different flight phases are relating to one engine or the other. It wasn't my intention to differentiate. It was a general statement of engine use.in an aircraft.Lifters aren't lifters as oils aint oils. It depends on design and suitability. I know of ONE engine failure due to a lifter on a Rotax. It was on the way to a Natfly. Documented. It's a rare happening. I am not saying the Jab has lifter failure but I believe manual adjustment is better as you can keep tabs on the wear of valves and condition of seats by the changing of the settings, which you don't know about it if adjusts itself automatically . This view is that of Camit I believe.

The Rotax runs too cold generally and the Jab often runs too hot. That and the fact the Rotax heads are retained better and the heads are much more stable dimensionally. (More even temperature. They don't give much problems except lead if avgas used) You expect this with liquid cooling. Also the barrels are steel on the Jab and alloy on the Rotax. The alloy conducts heat much better..

 

Maj Just noticing your recent post. IF anyone knows for sure what is wrong why not let everyone know?. People might conjecture, but let's get specific here, as that's what is required. Not knowing where this is going is not good practice. There are people out there who should be informed IF something concrete is known. I remain sceptical that they do, actually. Nev

 

r

More than happy to Nev, in fact I have been saying this for years now with nobody really listening. I feel the very basis of all the jab problems lies in the CNC machined- from -billet engine case, and I don't feel the problems will ever be solved ( by Camit or anyone) until such time as they change to either a cast or forged alloy case like everybody else uses. The only other engine block I know of which was CNC machined billet wa a drag race engine called a Donovan.

It was an exact copy ( with some improvements) to replace the old chrysler 'elephant' cast iron blocks which became hard to get. The Donovan wa only intended to be used for a couple of runs, and I don't even know if they still use them or not.

 

When you CNC mill something out of solid billet you release a lot of internal stresses which wants to throw the finished machine tolerances way out of wack. Unless you intimately measured every dimension on each billet case ( and there would be many to accuratly measure) and rejected those cases that were beyond tolerance, your basically getting what you get, and we've seen the results of that.

 

Additionally a billeted case with a rotating steel hot crankshaft within trying to escape, and very hot steel cylinders attached to it is thermally unstable at best. Your asking for hot spots. The alum wants to move around and expand way more than the steel, hence why they break cylinder and case studs all the time.. Lets remember even the new upgraded ones are still breaking, and there's only one common denominator ...the alum billet cases. Same with the billet heads...not thermally stable enough. Lets get to the valves now, their design is archaic at best. They didn't 't even have oil supply galleries in their valve guides until recently, critical to keeping an exhaust valve cool and eliminating excessive wear on bronze valve guides. Exhaust valve seats set in billet aluminium will not stay there...once again the thermal expansion thing between steel and aluminium ..and for them to have half a chance the valve clearance is absolutly crucial ...too tight with no clearance and its all over red rover very quickly with the valve seat.

 

And if all this is no enough let get to the oil cooling situation on the Jab....ah ....second thoughts, let's not !......I mean what other engine have you ever come across where you have to consult the operators manual to get your proper oil level on the dipstick for your particular engine !....and then have to be happy with 1/8" of oil on the end of the dipstick !...come on now.

 

And Camit ?........looked over their 'new' case at Natfly last,.....same billeted case to me.....oh and what's all these funny oil lines running all over the place?...........oh they are so you can squirt a little oil into the cylinder so the barrels won 't rust when your done flying, replied the friendly sales lady ....give me a break darling, why don't you use high grade carbon or chromium steel like everybody else for your cylinders, and the damn things won't rust in 50 years.............!!!.. So what the magic answer in my opinion ?....go to a cast or forged alloy case like Lycoming, Continental, Pratt & Whitney and Rotax have used for years, and I reckon reliability will improve overnight. Thanks for asking..........

 

 

[motzartmerv]

Casa are certainly up to something, I have a few letters of request that are unusual to say the least.

 

Why are we comparing Jabs to Rotaxes here? Apples and oranges lads. One is as good an aircraft engine as you could reasonably expect to buy, and one ...well...just isnt...

 

One will "most probably" give you years of faithful, trouble free service, the other will " most probably not".

 

 

[facthunter]

Maj. Thanks for your reply. I wish I had gotten to speak with you at Lethbridge. Is there some one who is known or considered to be the "expert" on these things?. Over the years I have seen a few L2's who are self styled as such. but there's not much there when you get down to it with some of them. I have also been to a lot of "educative " Jabiru occasions and am not very impressed so far.. Cast cases have to be annealed and heat treated too to reach highest strength, (as you know) It's a pretty savage process. I understand the heads by Camit are a stronger alloy than previous spec. Everything helps. I don't want to see people (owners and operators) being hung out to dry, with someone spending their money or destroying their investment, without a good result being obtained. Nev

 

 

[facthunter]

Merv, the Rotax is best not fiddled with. It's that kind of engine. You just look after the coolant the carb rubbers balance the carbs so the engine is smooth and use clean good mogas Also the cylinders don't rust when you don't fly it for a while. When it reaches its stipulated life you can't economically repair it. You get a new one for almost the same price. This means for the average bloke the motor is something you don't have to get involved with much. The jabiru is not the same animal. You need to know it is running right and do the things properly that are needed to be done to have any assurance of a good run. It's more hands on, but don't fiddle for the sake of it and don't work on it if you don't know what you are about.. Nev

 

 

[motzartmerv]

And there in lies the problem..:)

 

 

[Guest Maj Millard]

Nev , to qualify what I posted above. After studying full time for two years at a reputable Aeronautical academy in the States and gaining my FAA Airframe and Powerplant license (A&P) I sat with the schools career advisor one day to discuss my future in the industry. He offered good jobs with the airlines, or bigger money repairing high- end carbon- fibre aircraft components ( I also had done an extra two months to gain an ICAO level 2 advanced composite certificate).

 

He also said there was an opening with a company called Peterson Precision Engineering which made high-end precision aircraft parts. He told me if I really wanted to learn about metals that was the place to work at for a year or so, before continuing my aviation maintenance career.

 

I worked with Peterson Precision for the next two years as a CNC milling operator, mostly on new state of the art Mazak mills. I and one other engineer ( also a UL pilot ! ) worked away from the main plant at Redwood City in a sort of 'skunk works ' envoiriment, making many military related parts that I still can't really talk about. We machined those parts that nobody else in the country could make with tolerences down around 2 to 5 ten thousands of a inch. The company at the time was owned by a mathimatician and has made most of its considerable fortune during the Viet Nam period with military contracts. We machined parts from many metals including, billet alum, aluminised bronze, hard brass, and many many types and grades.of stainless steel. Because of the very tight tolerences and precision measuring capabilities, we always had a high level of finished part rejection...we filled a lot of scrap metal bins each week !....and knew the pickup guy pretty well.

 

When we got down to about only 8% finish acceptable parts from 100% blanks provided, on one much needed part, our company told the high- end customer that we didn't want to make the parts anymore. They basically replied you will give us the 8% or we will own your company in the morning.......and they were serious !...we continued to make the part.

 

The particular part was machined from a long alum custom extrusion. There were multiple machining steps which removed large amounts of metal from the bars. By about the third stage around 50% would be well out of tolerance and in the scrap bin they went. Nothing to do with the operator or machine.....all to do with the internal stresses locked up in the extrusion during manufacture.. We also made turbine blades for Lycoming ( yes Lycoming made a small turbine then ) and when things slowed down, breach blocks for Baretta pistols...If you buy one buy the Italian one , not the one from Baretta USA.... The yanks love there inches and the Italians love metric....mills are way more accurate in the machining world.

 

My career advisor was right, I learnt a shitload about metals and part making in that two years. !!...

 

 

[bexrbetter]

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

It also comes down to if you have 13K or 25K in your pocket or not.

 

As for the 12mm spanner in the Honda. How would it get into the sump if the mechanic was setting the valve lash..

There's plenty of large gaping oil drain back holes on many engines.

 

 

[Guest Maj Millard]

It also comes down to if you have 13K or 25K in your pocket or not.

 

There's plenty of large gaping oil drain back holes on many engines.

Always a Possibility of course, but not expected to be the case on this one.

 

 

[Guest Maj Millard]

Well it appears the Donovan engine company is still well and truly in business, but they have moved on from their original alum billet cases. they are now Strontium modified B356 alloy with special heat treatment. Cylinder sleeves are ductile Iron centri dry sleeve sourrounded by cast alum.

 

Well there's money in drag racing that's for sure...!....

 

 

[Old Koreelah]

It also comes down to if you have 13K or 25K in your pocket or not...

If Jabiru engines- with all their limitations-hadn't been available, many of us might never have gotten off the ground.

 

 

[jetjr]

So Maj all we have to do is get rid of the block, heads and valves. Then make them out of so,ething we cant afford and it will all be ok? How simple, thought you said earlier that the problem was valve fouling?

 

Pretty complex AD Id say

 

POST EDITED AS IT DOES NOT ADD VALUE - MOD You have your opinion and I respect it for what its worth but others disagree and are working on fixes that are constructive and achievable and affordable.

 

There are plenty running without problems and failures are poorly documented or researched.

 

Everyone agrees they need improvement and maybe Jabiru canat or wont effect the investigation and upgrades.

 

 

[dazza 38]

So Maj all we have to do is get rid of the block, heads and valves. Then make them out of so,ething we cant afford and it will all be ok? How simple, thought you said earlier that the problem was valve fouling?Pretty complex AD Id say

To simply say they are no good and the answers are well known is BS. You have your opinion and I respect it for what its worth but others disagree and are working on fixes that are constructive and achievable and affordable.

 

There are plenty running without problems and failures are poorly documented or researched.

 

Everyone agrees they need improvement and maybe Jabiru canat or wont effect the investigation and upgrades.

Deadsticks failures are well documented and researched.

 

 

[alf jessup]

jabiru are 1000 hour TBO not 2000Rotax 2000 hours

 

their is a diff between top and bottom ends

Deb,

 

Might want to look in the Jabiru engine manual section 2.8 & 2.9 unless I can't read it states the valves & top end are expected to be replaced at 1 cycle (1000hrs) and the engine is expected to make 2 cycles (2000hrs) before requiring a full overhaul.

 

Alf

 

 

[dutchroll]

If Jabiru engines- with all their limitations-hadn't been available, many of us might never have gotten off the ground.

Also many might have been able to stay in the air.

 

 

[coljones]

If Jabiru engines- with all their limitations-hadn't been available, many of us might never have gotten off the ground.

And the important figure is not really TBO but MTBF. No-one seems to be collecting this figure which measures the average of the age all engines dead or alive rather than the statutory age of death, TBO. How many engines actually reach TBO. If the "quoted" TBO is 2000 hours and you fly 200 per annum you will need to fly 10 years to reach TBO. I am not sure if the latest survey, while gathering some important data, is gathering the life expectancy of all engines - not just the dead ones.

Calicivirus kills 100% of rabbits killed by Calicivirus but there are still lots of rabbits around The Oaks quite happy, healthy and bounding around and doing what rabbits do.

 

 

[winsor68]

... CASA isnt going to bring in new rules just for Jabiru

Already did back when they "certified" it didn't they?

 

 

[jetjr]

Deadsticks failures are well documented and researched.

Been through this, yes we know what was the end result not what caused it. As others have said to start replacing bits based on this kind of evidence is putting bandaids on a cut without finding out how you cut yourself. It going to happen again.

 

 

[jetjr]

Already did back when they "certified" it didn't they?

No, dont think so.

Also remember most of the engines we play with are not certified

 

With a stroke of a pen they could say they all need LAME annual inspection

 

 

[Guest Maj Millard]

So Maj all we have to do is get rid of the block, heads and valves. Then make them out of so,ething we cant afford and it will all be ok? How simple, thought you said earlier that the problem was valve fouling?Pretty complex AD Id say

To simply say they are no good and the answers are well known is BS. You have your opinion and I respect it for what its worth but others disagree and are working on fixes that are constructive and achievable and affordable.

 

There are plenty running without problems and failures are poorly documented or researched.

 

Everyone agrees they need improvement and maybe Jabiru canat or wont effect the investigation and upgrades.

Jetjr, yes it is my opinion, I was asked for it, and I was happy to give it. In respect to your comment " there are plenty running without problems" well that's not generally what I have observed over the years. Many who have had "no problems" have had to experience constant upgrades and changes with mixed results or success, installations of 'exchange' engines when theirs have failed mysteriously, numerous trips to Bunderberg, and many hours of unwanted maintenance on the ground when they would rather have been flying. If you want to call that ' running without problems' then your more than welcome to your opinion. This has been going on now for at least twenty years and still the failurers occur without a proper factory explanation, testing or solution. Only time will tell if my assessment is on the money or not. In the meantime customers are finally starting to vote with their feet, evidenced by the number of Jabs for sale in our magazine and their corresponding drop in value on the open market.

 

 

[motzartmerv]

Sad but true. Owners can't give them away:(

 

 

[facthunter]

I'm not surprised. I understand peoples concerns, but there is a lot of non constructive comment. If the failures were all the exact same part or a couple of parts the solution would be simple.®. If anything is going to be achieved we need a very disciplined approach, not emotional. Nev

 

 

[AVOCET]

Sad but true. Owners can't give them away:(

Its amazing how the price of jabs has dropped , bad news travels fast .

Definably a buyersmarket ,

 

Theres a few around these parts that just sit in the hanger as pilots are to scared to fly or to broke to have the mods done .

 

And not flying them doesn't help the engine .

 

 

[facthunter]

It doesn't help the engine at all. They should be inhibited if left unused. Running them for a short time on the ground is not a good idea either. There should still be information on the CASA site about it. Nev