Jab engines

My Jabiru is one of those Russ. S/N 425 and 1998 kit. A later AD said that the fuel tank sloshing compound was not suitable for use with ethanol in these planes.

Onetrack ; I cant come up with a technical argument however I would point out that a number of European derived aircraft now state that their Rotax motivated aircraft can use/are approved for up to 10% Ethanol blends. Rotax say much the same thing.

Ethanol absorbs water. If the engine company is going to be held legally liable for failures which may be associated with water in the fuel then of course they will issue a statement banning ethanol.

This has the effect of putting the onus back on the operator, where it belongs in my opinion. You need to research the subject and only then maybe use it, taking care with the exact ethanol fuel you are using.

The method of finding out if the fuel you are using contains ethanol is to put a bit of water in a sample and shake. If the water goes "away" then that indicates ethanol.

Agreed, Planey. Just trimming it back a smidgeon, within tolerance.

 

Yesterday arvo I poked my inspection camera down the plug holes. Wish I hadn't; up close, the encrustations on top of the piston look like massive geological structures.

I've been religiously using AvGas for a decade, mostly for it's known quality, but would love to get away from lead. Is there any additive I can use to clear those internal deposits?

Yessir, I had the same reaction after inspecting my pistons during the first 100 hr check, more crud than I expected, anyway. Exhaust valves have me guessing even more. I have started using TCP: TCP Fuel Treatment, 1 Quart | Alcor, Incorporated A very popular additive up here, recommended by A&P's as well. I think it's more of a preventative to build-up rather than a cure, but I will be monitoring closely over the next inspections.

That sort of build up can cause incandescent spots and pre ignition. It's not easy to remove either but I think I would be doing something about it. Usually some of the build up is DUST that bonds with some carbon. Nev

I operate a 80gee gee solid Jabby donk and I use 95 RON with a flashlube mix, 480 hrs, the Pistons valves etc are whilstle clean as far as I can tell/see?

Ag

I've been religiously using AvGas for a decade, mostly for it's known quality, but would love to get away from lead. Is there any additive I can use to clear those internal deposits?

Its called ULP - nice clean burn. Minimal deposits. Minimal pollution. Whats not to like ?

Its called ULP - nice clean burn. Minimal deposits. Minimal pollution. Whats not to like ?

Exactly!?Combine the use of ULP AND this funnel means I sleep like a baby???

It varies and is not a controlled product and can be contaminated by un authorised additives. It really doesn't belong in an aviation scene where quality assurance is a common safety concept. That's what's not to like. Nev

Now let me see, controlled product? Hmmmm in the late 99 (I think it was) the so called 'controlled' product IE: 100 Oct was severely contaminated down Sth playing havoc with plenty of A/C fuel systems grounding LOTs of GA piston machines! ANY fuel is a man made product handeled by man used by man, that guarantees nothing!

The standard was there and broken. Costs were paid out. Some planes never flew again. There's NO set standard for mogas and WE get some of the worst in the world (a fact that's well known in our auto industry and of great concern to them for that and our diesel and the government just recently lowered regs and checks . on it.. You prefer that do you? A completely unregulated product capable of being adulterated at every stage.? That exception you quoted actually proves the rule. A rule applies. Nev

It varies and is not a controlled product and can be contaminated by un authorised additives. It really doesn't belong in an aviation scene where quality assurance is a common safety concept. That's what's not to like. Nev

In support of Facthunter's comment, I noticed variability in mogas which was causing problems so I switched back to avgas.

It's called CHOICE, I think there a few planes flying around using Mogas, I don't see the countryside littered with bodies from Mogas planes falling out if the sky!

Very science based reply. Not. Of course it's your choice and it's legal. The more informed a choice is, the better the decision made. MOGAS is many thing s Not ONE thing. That's the PROBLEM with it.. In Europe another situation entirely exists. OUR fuel here has been sub standard for years. I've had enough trouble with cars running on it and seen the insides of some aero engines over the years. Currently I just cannot recommend it. Ethanol is the least of your problems but still a problem for some systems. You COULD safely run on ethanol if the motor was tuned for it and nothing else was available. Currently it's not economic. Nev

It is a matter of choice and availability. The nearest Avgas facility to me is a 40 minute flight and $15.00 landing fee. I don't like the lead or the deposits left in my engine by Avgas despite it having a measure of quality control better than Mogas. I used to use BP 95 Mogas by choice and of course availability but the availability has now disappeared with the local BP stations no longer stocking it having replaced it with an ethanol blend 94. I use 98 Premium Mogas exclusively which provides the same power at least as Avgas, is much cleaner burning with no lead and I have not had a quality issue in 5 years. I always filter it through my Mr Funnel & have never found a speck of dirt or moisture. The only possible issue as far as I know is vaporisation and that is generally confined to above 10,000 feet where I don't go & even then I have an electric fuel pump directly below the main tank which will push liquid fuel through should there ever be any vaporisation.

I would say most of the RAA fleet in Australia run on Mogas. This includes almost all of the Rotax engined aircraft and probably the majority of the Jabiru engined aircraft.

Very science based reply. Not.

 

Of course it's your choice and it's legal.

 

Thank you Nev?

Another gotcha, you think? It's a quote out of context. A cheap pointscore not worth a lot if we are to discuss things in any depth., Don't bother thanking me when it's not meant in the right spirit. Nev

Think about it. Nev

When my CH701 was at Coominya I ran the Jab engine on 98 Mogas, but when I moved it to Warwick which has a 100LL bowser I started using that because it is easier (if dearer!) and really haven’t had any problems with either! Always interesting reading other people’s experiences and opinions.

I have used Avgas exclusively since purchasing my Jab new in 2014.

I do this because this is what the Manufacturer recommends, and is supported by a comprehensive analysis done by Jabiru some time ago.

I have not had any problems with Avgas 100LL and dont see any readon to change.

Hmm - Nev are you sure that Au has no standard(s) for MoGas ??

I was always under the impression that standards for auto fuel (petrol/diesel) were considerably lower/ variable say in the early 1970's (when I started to take notice of these things).

A combination of pressures - green (environmental pressures) and auto manufacturers (needing to meet the new pollution standards - combined to force up the standards and markedly reduce variability.

I have been using PULP in my Rotax 912 uls for 10 + years and have never had a problem (not scientific but real life)

The standards were just further relaxed in the last few weeks or less. Very recent. They don't shout it to the rooftops. We are miles behind other countries and getting worse.. We also hold less reserves.. There's always concern by auto marketers and service people here about it. It's part of the push to cut so called "green' tape and lower standards and cut costs. Nev

We have Fuel Standards for every fossil fuel used in transportation in Australia, under the "Fuel Quality Standards Act 2000". There are set parameters for many features of the fuels - even the maximum water level content of ethanol!

However, much of the legislation around fossil fuels, is about lower emissions and ever-cleaner fuels.

The current gripes about "poor quality fuels" in Australia, centre around the sulphur content of our fuels, which is still higher than many other "developed" countries.

https://www.environment.gov.au/protection/fuel-quality/standards

https://www.environment.gov.au/protection/fuel-quality/standards/petrol

The largest percentage of our transportation fuels are refined in Singapore, Sth. Korea and Japan - to meet Australian Fuel Standards. The fuels are checked and tested in the ship to ensure they meet specifications, before they are unloaded.

Any failure to meet every fuel specification in the Standard, means the fuel is not allowed to be unloaded, until the problem is remedied.

I note that he standards apply to 91 & 95 RON and surprisingly there is still an allowance of 5mg/L maximum for Lead. There is no standard for 98 RON fuel. My assumption here is that the 95 grade is used as a base and the fuel companies own blend of aromatics is added to bring the octane rating up to 98. The interesting thing about 98 was shown in the BP study on Petrol life in vehicle tanks done in 2010 when they found that as the lighter aromatics began to evaporate off the octane rating went from 98 to 99.5 over a period of 5 weeks although this was found to then increase the likelihood of detonation in high revving engines.

................................................................................................................... The interesting thing about 98 was shown in the BP study on Petrol life in vehicle tanks done in 2010 when they found that as the lighter aromatics began to evaporate off the octane rating went from 98 to 99.5 over a period of 5 weeks although this was found to then increase the likelihood of detonation in high revving engines.

Hi Kg - My reading of this report,is, if the fuel is kept in a sealed container, at 75% capacity or better, the changes you refer to take many many months to occur and then at much slower rate. If this is correct storing 98 for 6 months is perfectly acceptable/satisfactory.