Jabiru mixture

[Yenn]

Go back to the starting point of this forum for what I think. I haven't talked to Jabiru, but I think the April 1 theory could be correct.

 

Spacesailer. How do you fly at 100mmph? Surely micro miles per hour is too slow to support flight

 

 

[spacesailor]

Just another typo.

 

or

 

Ive got the shakes.     lol

 

spacesailor

 

 

[skippydiesel]

Forget the engines; what are your thoughts on the Automotive Mixture Control System? There's a description and a mockup here: https://jabiru.net.au/    Scroll down the main page.

Sounds a bit odd to me -  Does that mean you set your carb to deliver a high fuel mixture & the gizmo then corrects it by admitting more air? The fail safe back to carbi will then run rich for how long? 

 

 

[facthunter]

. I'm not much the wiser from anything there.

 

    . As said you can only lean an already rich mixture and also the manifold (vacuum? ie suck) is higher at low throttle openings. (not mentioned anywhere I can seeing the bumph. but it's something to take into account .I agree getting even mixtures to multiple cylinders is a difficult task from  a single point "anything". "Gami" injectors did this with the common old mechanical injection systems  quite satisfactorily and you don't need an auto system as it's a totally different environment it's tailored to work to with multiple and rapid throttle changes at mostly low power and lots of NO power (idle) with short periods of high power.. I question whether they are actually as trouble free as some allege. They are certainly not easy to troubleshoot when they are playing up.  Nev.

 

 

[SSCBD]

So my real questions are with the GEN 4, and where do you get real information from.

 

1. How many gen 4 engines have been put into aircraft to this date. Number IS ?

 

2. How many high  hour  engines  are operating without failure  say at 500 , 1000, 1500?

 

3. If any failures what are they and WHEN??

 

Anything else is pure smoke and mirrors or guess work here.   

 

 

[turboplanner]

So my real questions are with the GEN 4, and where do you get real information from.

1. How many gen 4 engines have been put into aircraft to this date. Number IS ?

 

2. How many high  hour  engines  are operating without failure  say at 500 , 1000, 1500?

 

3. If any failures what are they and WHEN??

 

Anything else is pure smoke and mirrors or guess work here.   

If you're looking at cost of life analysis, for example if you were running a flying school, you would be looking for this sort of information albeit probably using 1000, and 500 increments to 2500.

 

If you're looking at the reason for the CASA Instrument you'd be asking how many forced landings per year, bearing in mind the issues reported publicly, although generally related to combustion chamber were random, some reported to have occurred on return from the factory. 

 

Because the issues were at random hours the telling evidence will be the record virtually from zero, becoming more compelling with every 500 hours.

 

 

[SSCBD]

If you're looking at cost of life analysis, for example if you were running a flying school, you would be looking for this sort of information albeit probably using 1000, and 500 increments to 2500.

If you're looking at the reason for the CASA Instrument you'd be asking how many forced landings per year, bearing in mind the issues reported publicly, although generally related to combustion chamber were random, some reported to have occurred on return from the factory. 

 

Because the issues were at random hours the telling evidence will be the record virtually from zero, becoming more compelling with every 500 hours.

No Turbo don't twist my post it is a fair and straight question -  I am looking at the gen4 engine, how many are flying now, and hours on them, and if any problems as per my post above. Shpuld not Raa have all these numbers as well?

 

 

[turboplanner]

No Turbo don't twist my post it is a fair and straight question -  I am looking at the gen4 engine, how many are flying now, and hours on them, and if any problems as per my post above. Shpuld not Raa have all these numbers as well?

You could contact RAA, but I haven’t seen data collected for general use in analysing  life cycle costs. I’ve always had to interview owners one by one and build a spreadsheet, and there are always some apples and pears issues to discard.

 

 

[Bald Eagle]

So my real questions are with the GEN 4, and where do you get real information from.

1. How many gen 4 engines have been put into aircraft to this date. Number IS ?

 

2. How many high  hour  engines  are operating without failure  say at 500 , 1000, 1500?

 

3. If any failures what are they and WHEN??

 

Anything else is pure smoke and mirrors or guess work here.   

SSCBB, these are fair questions that I feel need to be asked.

 

Maybe someone might have to ask Mr Jabiru himself and whilst they are at it confirm if this original thread is a 1 st April hoax or not.

 

Are there any CASA standards or testing regimes these engines go through before they are used for aviation use, especially commercial use, flying schools ?

 

 

[Old Koreelah]

All nice ideas, Bald Eagle. If implemented, who would consider manufacturing an aero engine? The market is tiny, and now you want to greatly incease the set up costs.

 

 

[fly_tornado]

you sort of imagine that the Gen 1,2 and 3 engines will continue to hurt Jabiru's reputation for another 15-20 years

 

 

[Thruster88]

If you're looking at cost of life analysis, for example if you were running a flying school, you would be looking for this sort of information albeit probably using 1000, and 500 increments to 2500.

Just helped replace the Rotax 912 in the club aircraft at 1500tt. Sold the old engine with 500 to run, our capital cost worked out at $12 per hour. The new owner even if he takes the engine to the tip at 2000 is up for $17 per hour with a lot less capital outlayed, I don't think this is expensive. Haven't had any previous 912 experience but the plumbing was very simple.    

 

 

Jab 200/400 with a 915 at 700kg MTOW would be an absolute world beater.

 

 

[planesmaker]

My J400 with 914 is a great combination! Very happy with it. 

 

 

[facthunter]

 Time will tell with a lot of this..  In service experience is always important  but the way they are used is very variable . I have no reason to think the New Jab engines will be more of a problem than the earlier ones. and there's quite a chance they will be much better .. To regard 2,500 hours as  a time to consider and compare is a bit of an EXPECTATION, of a fairly high order as practically no IC  aircooled aero engine goes that far and when and IF it does it's  how it's serviced  and operated becomes of the most significance. It won't go that long without attention to the Valves and you shouldn't expect it to..Nev

 

 

[Thruster88]

 Time will tell with a lot of this..  In service experience is always important  but the way they are used is very variable . I have no reason to think the New Jab engines will be more of a problem than the earlier ones. and there's quite a chance they will be much better .. To regard 2,500 hours as  a time to consider and compare is a bit of an EXPECTATION, of a fairly high order as practically no IC  aircooled aero engine goes that far and when and IF it does it's  how it's serviced  and operated becomes of the most significance. It won't go that long without attention to the Valves and you shouldn't expect it to..Nev

There have been plenty of lycoming's that have done 2500+ I know of one personally. The 0-235 has had  a 2400 tbo  for a long time. That's the 152 engine, sure they may have problems but they nearly all ways make it back to  the shop.

 

 

[facthunter]

I don't know of any that make over 2.000 hours without top work The basic engine does that FIGURE often. They have tried hard to get the valves etc to go for that time but it's unusual (if ever) and there are often bore rust problems in little used engines.. or engines left unused for even short  times and not inhibited. Having a TBO of 2500 hours doesn't say it won't need top work during that time. You do a compulsory Comp. check every annual or 100 hours and continued use is subject to that being satisfactory. Nev

 

 

[Jaba-who]

I don't know of any that make over 2.000 hours without top work The basic engine does that FIGURE often. They have tried hard to get the valves etc to go for that time but it's unusual (if ever) and there are often bore rust problems in little used engines.. or engines left unused for even short  times and not inhibited. Having a TBO of 2500 hours doesn't say it won't need top work during that time. You do a compulsory Comp. check every annual or 100 hours and continued use is subject to that being satisfactory. Nev

Yep. I had an Lyco O320 for about 6 years. Flew it typical private/recreational hours (75 to 100 hours a year for a couple of years then progressively less over the succeeding years) 

 

Bores glazed and needed Flexi honing  in that time due to inadequate use. 

 

Even if all else were ok I wouldn’t call that getting to TBO but apparently a lot of people do. Advertise their engine as making TBO  because it still has the main original parts. but in actual fact has a few new valves, been flexihoned, maybe have a new set of rings etc. 

 

 

[turboplanner]

The whole scene is changing with new materials and better design, so it’s not unusual for reconditioned engines to have a longer life than the original base engine. In terminology, life cycle usually refers to time to a full rebuild, and not to maintenance such as valve grinds or replacements.

 

 

[Downunder]

Jab 200/400 with a 915 at 700kg MTOW would be an absolute world beater.

It would take new management, with a mentality to drag Jabiru into the 21st century..... 

 

 

[skippydiesel]

The whole scene is changing with new materials and better design, so it’s not unusual for reconditioned engines to have a longer life than the original base engine. In terminology, life cycle usually refers to time to a full rebuild, and not to maintenance such as valve grinds or replacements.

How long have you been asleep - valve/seat replacement/grind, head decoke, new rings/pistons etc etc is not maintenance its a reconditioned engine that did not make it to TBO.

 

This is the sort of stuff I did as a youth in Britain, when it was commonplace for the average home mechanic to perform on his trusty Morris/Ford/MG/Triumph, etc etc.

 

This is all ancient history - the advent of better materials, more prise & repeatable machining, better & consistent fuel quality, lubricants, etc etc has removed the need to perform this sort of surgery almost completely.

 

Any engine series that has a high incidence of this sort of mechanical intervention is just unreliable.

 

 

[turboplanner]

How long have you been asleep - valve/seat replacement/grind, head decoke, new rings/pistons etc etc is not maintenance its a reconditioned engine that did not make it to TBO.

 

This is the sort of stuff I did as a youth in Britain, when it was commonplace for the average home mechanic to perform on his trusty Morris/Ford/MG/Triumph, etc etc.

 

This is all ancient history - the advent of better materials, more prise & repeatable machining, better & consistent fuel quality, lubricants, etc etc has removed the need to perform this sort of surgery almost completely.

 

Any engine series that has a high incidence of this sort of mechanical intervention is just unreliable.

I haven't been asleep for long.

 

I'm not talking about engine rebuilds involving rebores, rings, bearings; just decokes and valve grinds at regular intervals which are not evidence of an engine failing to reach TBO (Time Between Overhauls.)

 

This is a definition of the Overhaul in TBO

 

"Every engine must be totally disassembled and the wear and tear of each part evaluated separately" (Source: Sapling.com)

 

 

[skippydiesel]

This is a definition of the Overhaul in TBO

 

"Every engine must be totally disassembled and the wear and tear of each part evaluated separately" (Source: Sapling.com)

 

Sorry to disagree - The definition you quote belongs to a past era - we no longer accept this level of "maintenance" as routine (in internal/piston combustion engines). I would strongly argue that any engine series that requires this level of intervention as a routine is NOT making TBO by current mechanical engineering standards/expectations.

 

We (the public) expect engines to remain in operating condition, without invasive surgery, for the manufacturers claimed life expectancy and by enlarge this is the case. Exceptions are infrequent & often as a result of sub optimal operating conditions/service.

 

 

[turboplanner]

Sorry to disagree - The definition you quote belongs to a past era - we no longer accept this level of "maintenance" as routine (in internal/piston combustion engines). I would strongly argue that any engine series that requires this level of intervention as a routine is NOT making TBO by current mechanical engineering standards/expectations.

 

We (the public) expect engines to remain in operating condition, without invasive surgery, for the manufacturers claimed life expectancy and by enlarge this is the case. Exceptions are infrequent & often as a result of sub optimal operating conditions/service.

Doesn't matter whether you agree with me, you have to agree with CASA, and this CASA definition is pretty much the same as the one I gave you

 

"Time Between Overhaul (TBO), which specify how long they consider their product should remain in service. These recommendations are based on average utilisation and conditions and usually recommend that the item be fully stripped and returned to the original specifications. "

 

The CASA definition came from this link which has more information on TBO

 

AWB 02-1 Issue 1 - On-condition maintenance

 

 

[facthunter]

A TBO is the upper limit of the life of the engine. Some parts or engines may also have a shelf life, a period in service limitation, a total engine hours in service limit.. An "on condition" extension is sometimes available where the engine is allowed to operate beyond the (normal)TBO. It has been sometimes found that such engines may require more expense to rectify than those "pulled" at the normal time. That is not unexpected.

 

A refurbished engine is inspected, cleaned, remachined if outside tolerances, re nitrided if applicable. NDT applied to some parts and some parts replaced and returned to a "zero time" status which clearly is NOT the same as a NEW engine but sort of works as if it is.. After successive rebuilds some parts become unreliable due fatigue or dimensional limits. Crankcase deck heights for example where the bearing crush is restored by facing the surfaces and align boring the cases. Even IF they are still within limits the cases may be likely to fail after a long total time in service. An engine that suffers an overspeed may be scrap depending on the type and duration and extent of the overspeed.. A heat treated part may also be US if it has gone over a certain Max temp.. TBO is not a fit and forget concept where everything runs predictably till it suddenly is not allowed to do any more. Defined Monitoring and inspections are required all along the way, for metal in filters, corrosion/ scratching of bores Compression leak down rates, head and case cracks and stretching of exhaust valves and seat condition and guide wear limits. Nev

 

 

[spacesailor]

Doesn't make sense to me. The cost of labour to strip an engine, AND NOT replace All wearable parts, is a waiting game, as it Will need those parts replaced at a later date. !.

 

O K if owner is doing the work & not counting their hours of labour.

 

Who on the old Ford / Holden motor's never put new "valve stem seals" in their motor as the old ones never gave trouble,?.

 

spacesailor