CASA - Draft Proposal for Jabiru Aircraft

[Guest Maj Millard]

Just a quick one nev. When you search the jab sales website does it say " evolving design" in th engine specs?If you buy soenthing you should expect it to work as is.

Been 'evolving' now for 25 years !....glad it didn't take that long for the Merlin or Frank Whittles turbojet....

 

 

[Guest Maj Millard]

Ross, I was just defusing - not interested in getting into an online blue with someone I've never met.Laurie

Not a blue mate ....online constructive discussion is what we do here.....

 

 

[facthunter]

You don't have a controlled situation when using mogas. That's a fact. When you do use mogas you want many more things going for you. I think the max cyl head temp on a P&W R 2000 was 235 degrees C. That's probably got a lot to do with the heat treatment process of the aluminium alloy for the head. Perhaps the 180 figure is derived by a similar process. for the Jabiru.? Nev

 

 

[facthunter]

Maj The Merlin was developed from previous designs and kept being developed during the war till the Griffon was fitted. There are plenty of other examples of radial engine development that went to on for a long time. It happens all the time, even with Jet engines. They keep upping the power and temps and metallurgy. Nev

 

 

[Guest Maj Millard]

I'm left wondering this.... Just what do some of you people want Jabiru to do?The through-bolts are already oversized. Do you want them bigger?

Do you want CASA to ban air-cooled engines? At least the only one they can, that is the Jabiru one?

 

Don't be confused here... CASA can only stops things, it can't make anything good happen.

 

I THINK you want Jabiru to transcend the laws of physics and chemistry, to make Jabiru engines magically immune from these laws.

 

Finally, I have to agree with Motzartmerv and say that the Jabiru handbook max temps are too high, they are MAX temps and they assume there are no other issues, like the fuel being less than perfect. I agree with staying well under these temps.

We want the through bolts to be strong enough to do the job....period. Lycoming, Continental or Rotax don't break through- bolts...it's extremly rare, except on Jabs where it's common lately.

Stop blaming the fuel ...the 912s' use the same stuff and they don't suffer from pre ignition....not the fuel.

 

 

[facthunter]

Because they are liquid cooled. Don't tell me mogas is a guaranteed product. I've had stuff my car will hardly run on. Hate to think of what it would do to an aero engine. Nev

 

 

[Guest Maj Millard]

Maj The Merlin was developed from previous designs and kept being developed during the war till the Griffon was fitted. There are plenty of other examples of radial engine development that went to on for a long time. It happens all the time, even with Jet engines. They keep upping the power and temps and metallurgy. Nev

Agreed Facto ...but generally each 'new' redevelopment becomes a new engine or at least a different Mark or - model...not a continuous upgrade of the same engine...in those military engine circles an engine requiring constant redevelopment or upgrades would be considered a bad or unreliable engine.

 

 

[Guest Maj Millard]

Because they are liquid cooled. Don't tell me mogas is a guaranteed product. I've had stuff my car will hardly run on. Hate to think of what it would do to an aero engine. Nev

Yes but I've run 912s on the same stuff now for going on 20 years with no major problems and no signs of pre ignition or detonation......both are generally caused by either hotspots ( pre- ignition) or incorrect octane fuel ( detonation). Most users are using the fuel grades that the engine is supposably designed for, just like everybody else.

 

 

[turboplanner]

Thanks for the clarification Ian.I, and many others here appreciate the value of this site and the effort that you and the moderators put into maintaining the standards even though some of us may get narkey about some of the editing that takes place.

 

The bottom line is it's your site and you set the rules.

 

I just wonder about post #441 in the "Yet another jab down" thread. Seems to me to contravene rule 2.5 pretty comprehensively. I understand the frustration in that post but leading by example would have been a better option in my opinion.

You're a bit of a worry gandalph, why not just leave it.

 

 

[motzartmerv]

Fuel, interesting and always comes up as a possible cause.

 

Our first through bolt popped on an engine that had spent 100% of its life on AVGAS.

 

I accept that someone may be very unlucky and get a carby full of dodgy fuel. Maybe, once in a blue moon. I know it doesnt have the same regulation of AVGAS, but the higher quality fuels should be ok, after all, people put it in cars worth much much more than our little jabirus's. Imagine the uproar if a bad batch caused the destruction of a few mercedes and a couple of porshe's.

 

The engines we have run on high octane mogas look so much better when stripped, no lead deposits, nice charcoal colour instead of grey. What is the mod required to Lyc engines to allow them to run on Mogas? I know it aint bigger through bolts and liquid cooling:)

 

 

[turboplanner]

The RAA reports, which come from pilots and owners never indicate which cylinder the through bolt or exhaust valve failed on. Is anyone aware of any commonality or failures, or any cylinder which has never had a failure.

 

 

[facthunter]

Dunno IF we can compare the resources and numbers of units of Companies like Wright, Pratt and Whitney. RR who nearly sent Britain broke with the engine for the 747 with Jabiru. There's some pretty ordinary engines stayed in service for a long time in the early days. The TOP engines of the Rotories. (Gnome and Rhone) lasted about 4 hours and there was nothing better at the time. The Merlins had a life of less than 400 hours .A Tupolev four engined turboprop that brought the Russian Ballet to Australia , the F/E proudly told me now had the engines doing 400 hours between overhauls.. Nev

 

 

[Guest Maj Millard]

Fuel, interesting and always comes up as a possible cause.Our first through bolt popped on an engine that had spent 100% of its life on AVGAS.

I accept that someone may be very unlucky and get a carby full of dodgy fuel. Maybe, once in a blue moon. I know it doesnt have the same regulation of AVGAS, but the higher quality fuels should be ok, after all, people put it in cars worth much much more than our little jabirus's. Imagine the uproar if a bad batch caused the destruction of a few mercedes and a couple of porshe's.

 

The engines we have run on high octane mogas look so much better when stripped, no lead deposits, nice charcoal colour instead of grey. What is the mod required to Lyc engines to allow them to run on Mogas? I know it aint bigger through bolts and liquid cooling:)

Generally Motz it involve lowering the compression or even raising it on some, modifying the fuel system to handle more vapor produced by auto fuel at altitude, and mods to the carb as required to handle mogas..

 

 

[jetjr]

More references to the concept Jabiru should do what rotax do........why?

 

It isnt relevant

 

Jab also isnt an automotive engine. One point correctly made is that some Rotax can handle, due to design and liquid cooling, a wider range of fuel quality. A good thing but doesnt mean any engine can or should.

 

Mogas quality is highly variable even changing quality in Days. Its been discussed here thta 98 is MORE volatile and variable than 95 and few recommend using the lower grade.

 

To say there isnt problems in cars is just plain BS, mechanics make aliving from it. Every week here my local guy gets a late model car with fuels quality problems. Generally leaves with a serious repair bill. Let alone the constant stream of small carb engines which wont start or run on it.

 

Google toyota D4D, diesel fuel quality and repair costs, maybe nissan ZD30,

 

Almost all cars now run EFI or closer to fadec to account for crook fuel mixes

 

 

[alf jessup]

There are always improvements in an evolving design. IF you are using that as a criticism, I can't see your point. It becomes a circular argument. Newer versions of many cars have "improvements". even Mercedes so should we take the older one in and request the mods be done to the older car for free?The 912 isn't without faults either. Some of the later (still 912) had a few quality control problems (You just don't hear about them)' The gearbox costs money too to service. The parts are VERY expensive. To say they NEVER need them is not quite true..

Just about every piston engine flying is aircooled. Plenty of them overheated. It's a lot easier to control temps when they are liquid cooled. Do we want all engines to be liquid cooled?.

 

I would not attempt to talk anyone out of using a 912, but what about the later blown version I haven't heard good reports of it at all. The 80 HP motor is/was about as good in the reliability stakes as any will be I reckon. Nev

Correct Nev,

 

The 912 is not immortal but it is not egg shelled either, 3 gears in the gearbox cost about $2500 for those 3 alone and that is just the cost of them, not the labour costs, the gearbox on the 912 is probably the weakest part of the engine and maybe the Ducati CDI ignitions the next but don't hear to much of them going but at about $1600 for a set there not cheap, hose replacements are about $600 - $800 bucks every 5 years but overall they are a very reliable engine with very little destruction going on in them, the 100HP is designed to run on 95 octane and the 80hp on 91 octane.

 

And yes the 80hp is the most reliable I have been told out of all the 912's

 

Just a little info for those who don't know.

 

Alf

 

 

[ozbear]

More references to the concept Jabiru should do what rotax do........why?It isnt relevant

Jab also isnt an automotive engine. One point correctly made is that some Rotax can handle, due to design and liquid cooling, a wider range of fuel quality. A good thing but doesnt mean any engine can or should.

 

Mogas quality is highly variable even changing quality in Days. Its been discussed here thta 98 is MORE volatile and variable than 95 and few recommend using the lower grade.

 

To say there isnt problems in cars is just plain BS, mechanics make aliving from it. Every week here my local guy gets a late model car with fuels quality problems. Generally leaves with a serious repair bill. Let alone the constant stream of small carb engines which wont start or run on it.

 

Google toyota D4D, diesel fuel quality and repair costs, maybe nissan ZD30,

 

Almost all cars now run EFI or closer to fadec to account for crook fuel mixes

These are pics of a 912uls with 1200 hrs on it run only on mogas carbon was wiped off piston with a rag inside tappett covers looks like new hone marks still in bore

 

 

[planesmaker]

Yep And a serious portion of the Jabiru engined aircraft require 120 hp. So the "compared to Rotax"debate is a waste of breathOpps sorry unnecessary capital letter in first sentence

Jet, speaking from experience I know that 100hp Rotax will definitely suit the 120hp jab fleet, in fact will out perform the jab powered aircraft if fitted with a C/S prop . Tom

 

 

[Guest Maj Millard]

Dunno IF we can compare the resources and numbers of units of Companies like Wright, Pratt and Whitney. RR who nearly sent Britain broke with the engine for the 747 with Jabiru. There's some pretty ordinary engines stayed in service for a long time in the early days. The TOP engines of the Rotories. (Gnome and Rhone) lasted about 4 hours and there was nothing better at the time. The Merlins had a life of less than 400 hours .A Tupolev four engined turboprop that brought the Russian Ballet to Australia , the F/E proudly told me now had the engines doing 400 hours between overhauls.. Nev

Facto, The RR Merlin and the RB211 ( I am assuming you mean this) were both totally new technology and pushing their respective envelopes for power development at the time. The Merlin was developed for maximum power output using high- pressure superchargers developing max manifold pressures. They were used in fighter interceptors and heavy bombers where high military-power was needed, for relatively short periods of time. 400 hours service was considered very successfull, and more than adequet considering the stressed nature of these engines. 400 fighter missions was more than enough in wartime.

The RB211 was a totally new concept with a multi-stage hi-bypass turbofan high-power and ultra high- pressure design using new carbon fibre first- stage compressor blades, never before developed or used. Of course there was a major development period with this engine as you would expect of any new cutting- edge technology.

 

The Jabiru is neither of the above however, professing instead to be a simple low to medium power four cylinder opposed petrol aircraft engine, non turbo or supercharged with a normal wet sump. It should be built with reliability in mind, and is low stressed with a relatively low compression ratio. It was designed and built in peacetime for sport aircraft use, so there was no hurry with it. It is not new technology...it has all been done before ..there are many like it in use in aircraft today, and have been since the dawn of aviation itself. There is no reason for it to be anything but reliable, at least to a comparable standard of say the 912. So why is it not as reliable in 2014.......that is the big question ?.......

 

 

[dutchroll]

Facto, The RR Merlin and the RB211 ( I am assuming you mean this) were both totally new technology and pushing their respective envelopes for power development at the time.

I was thinking much the same. It's not a very good comparison. We're talking cutting edge technology versus garden-variety 4 cylinder piston engine. I don't see how you can make a valid comparison with a Merlin or RB211. Incidentally, RB211s went on to become very reliable engines with later upgraded versions. A classic example of the manufacturer putting their money where their mouth is and putting in a massive effort to improve their product.

I can understand owners being a bit sensitive to the Jabiru situation and certainly understand them being unhappy with the proposed CASA restrictions, but when you get experienced LAMEs rolling their eyes (as I have witnessed on several occasions from highly reputable and competent LAMEs) and expressing total lack of surprise at another Jab engine failure report, you do seriously have to wonder......

 

 

[facthunter]

Lets get some facts out there eh. I would like to know just what the situation is, re number of failures that are due to the engine itself being defective. Also a proper detailed assessment of the nature of the failures and possible causes.

 

I believe the engine has some issues but I make the point (again) if you go after the jabiru there are far worse motors out there, that if you were consistent you would tackle too. I don't believe we should go down that path. either. The general state of knowledge about motors here is not high, nor would be in CASA either. The FAA have made some ill conceived observations on the Bing Carburetter too as an example of lack of knowledge in high places.. Engines these days are not tuned in the normal sense. They change the chip to get more power, rather than change port shape or valve timing.. There are many big manufacturers who have not made a successful attempt at making a simple aero engine. They would have succeeded if it was easy. You can't control all the conditions out there. I take the point that not everyone should have to be be capable of engine trouble shooting, but many of the older once reliable engines are not so reliable as thought.

 

I have NEVER seen anyone who has bothered to inhibit an engine not used for a while or even squirt some CRC in the cylinders. It is well known that rust has rendered many Jab cylinders dangerously unserviceable, but who cares? ALL steel cylinder rust. Not just Jabiru..Nev

 

 

[facthunter]

The Merlin wasn't certified for civilian use in most countries.( Canada being one exception) because of a non duplicated magneto drive skew gear. No engine is perfect. Not one. The CF6 GE after an engine failure at Ankara on Take off which took out the other motor as well with shrapnel, causing the plane to burn to the ground after an aborted take of was subject to a hot section inspection on every turn around consequently for a significant period after that.. GE make good stuff but some parts are critical. Nev.

 

 

[Guest Maj Millard]

Lets get some facts out there eh. I would like to know just what the situation is, re number of failures that are due to the engine itself being defective. Also a proper detailed assessment of the nature of the failures and possible causes.I believe the engine has some issues but I make the point (again) if you go after the jabiru there are far worse motors out there, that if you were consistent you would tackle too. I don't believe we should go down that path. either. The general state of knowledge about motors here is not high, nor would be in CASA either. The FAA have made some ill conceived observations on the Bing Carburetter too as an example of lack of knowledge in high places.. Engines these days are not tuned in the normal sense. They change the chip to get more power, rather than change port shape or valve timing.. There are many big manufacturers who have not made a successful attempt at making a simple aero engine. They would have succeeded if it was easy. You can't control all the conditions out there. I take the point that not everyone should have to be be capable of engine trouble shooting, but many of the older once reliable engines are not so reliable as thought.

I have NEVER seen anyone who has bothered to inhibit an engine not used for a while or even squirt some CRC in the cylinders. It is well known that rust has rendered many Jab cylinders dangerously unserviceable, but who cares? ALL steel cylinder rust. Not just Jabiru..Nev

Yes lets get some facts out there.....one your first point .....can you tell me which ( aero) engines are "far worse motors out there "...... ?? ....as you state.

 

 

[dutchroll]

No engine is perfect. Not one.

Some are less perfect than others.

 

 

[gandalph]

I am out for dinner with Corrine, it's her birthday, and as I can't see the post numbers on my phone I will check in the morning

Happy birthday Corrine! Hope you had a great day and an enjoyable dinner. Best wishes.

 

 

[Russ]

McCullocks..........owned one, my right arm is 2 feet longer than my left arm, just trying to get it started ( hand cranking the prop )