DonRamsay Posted November 27, 2014 Posted November 27, 2014 I really don't know why we keep this unending comparison up with Rotax. The motor is a totally different concept Correct as always Nev. Except, that there is, I believe, a misconception that the Jab engine should be tolerated because the initial outlay is cheaper than the Rotax. And there is the question of "fitness for purpose". Is a Jab engine fit to power an aircraft that is flown infrequently by a relatively low hours, amateur pilot and maintained by, at best a knowledgeable L2 and at worst, by a Pilot with little or no real mechanical expertise. I personally know of evidence in the real world of some Jabiru engines performing acceptably but we don't have a lot of reliable data to back know. By the same token there is plenty of anecdotal "evidence" that Jabiru engines rarely go more than 25% into their TBO (2,000 hr) range without requiring substantial attention and that many are replaced by 500 hours. Is that OK? If a commercial product of any kind was unable to achieve 25% of the manufacturer's claimed life they would be taken to task but for some reason this doesn't seem to apply to Jabiru. . . . the NEXT model even more so. They have gone down the high tech road and the "ordinary" pilot further removed from knowing what is going on (or not going on) with his engine. If the new Rotax featured stratified direct injection and turbo boost then I would be happy to give it the "High Tech" label. I think the iS Sport Rotax is a lot less ambitious than that - but it still achieves a significant advance in efficiency and reliability, despite the added complexity. As for "knowing what is going on" the new Rotax provides a great deal of real time information for the pilot with a glass screen (Garmin/Dynon etc) and recorded data for the maintainer to review. I'm talking about engine management and water cooling and reduction gears AND the ability for the owner to work on it etc This is like the argument we all had when EFI started to become common in the 1980s and an argument that faded when we just didn't need to work on the engine because they became so reliable even after hundreds of thousands of kms of poor operation and maintenance. As you would know, the addition of an extra digit on the odometer wasn't just due to the switch from miles to kilometres in 1974 but as a recognition that a car could last more than 99,999 miles in the old money. TBO has never meant to be "without work". The valves and heads of a conventional motor can be compared with the hot end of a jet engine which is often replaced before the rest is overhauled. Nev Fair enough. But it would seem reasonable to me that an engine with a claimed TBO of 2,000 hours should not need the heads off before 1,000 hours. 1
DonRamsay Posted November 27, 2014 Posted November 27, 2014 Don, the sprag cops a pizzling if theres any loss in Crank from the batt.. We learned this the hard way... As did we :-( Most of our rotaxes 'rough spot" is at around 3-3500 range. Have never had up as high as yours. How long has it been like that? It is in a Tecnam Sierra and, as we've had a wing off for a couple of months replacing a couple of ribs, I'd be guessing but I think for a couple of hundred hours. It is not severe and hasn't got a lot of interest from me as I am rarely in that rev range. The carbies were balanced by a competent L2/L4 50 hours ago at the last 100 hourly.
motzartmerv Posted November 27, 2014 Posted November 27, 2014 Oh yea ok. Most pilots dont even notice the rough range, and as you say, if it not in a 'spot' where your likely to leave it, its not a concern..
Ian Burdon Posted November 27, 2014 Posted November 27, 2014 It has been suggested some pilots not coping with engine failures could be a reason for the draft proposal for Jabiru aircraft. Please don't say the fatalities have not been in Jabiru aircraft as it really is not the point. The point is this thread is about, quote : CASA - Draft Proposal for Jabiru Aircraft. unquote. So don't try to say that these fatalities have anything to do with flying a Jabiru. Start another thread perhaps? 1
motzartmerv Posted November 27, 2014 Posted November 27, 2014 I really don't know why we keep this unending comparison up with Rotax. Why not? Sure they are designed differently, but when looking at 'suitability' surely comparing ANY product to what else is available is standard stuff for any discerning buyer/operator/regulator. A manufacturer of any product should always be asking " What SHOULD our product do" what benchmark can we set to work towards. What effect on reliability can we expect to find in the differences in design. Saying we cant compare Rotaxes to Jabs is a bit like saying we cant compare apples to oranges..They are both fruit..!!.. When the regulator want s to find "acceptable levels" of ANYTHING, surely they look at 'the levels' themselves and as such, look at other engines. Ok so its a budget engine, so maybe it could be expected to have double the failure rate of the "other engines". Ok, by looking at recent figures we see that no, its more like 4 times the failure rate.. Acceptable? Maybe..I dont know...But, certainly needs looking into particularly when the highest levels of failure are in the very MARKET the aeroplane is designed for....Training!. So to go a bit deeper.. Any investigation into an operation itself would HAVE to compare failure rates.. If a school has ZERO major engine issues with one make of engine, and 100% failure rate with another and usage levels roughly equal,, this discrepancy MUST be explained. If a school had the same amount of failures regardless of engine type, then sure, the finger starts getting pointed towards the operation, logically.. 1
facthunter Posted November 27, 2014 Posted November 27, 2014 Don You still have to watch things on the 912 They have a dog's breakfast cooling system and rubbers that crack on the Carbs and carb balance difficulties. Not everyone want's a water cooled system because air is there and you don't need radiators, hoses pumps and some way of regulating the temps. You SAY certain things are not acceptable in this day and age. They sell cars on the basis of the owner never lifting the bonnet and half the time you can't even find a dipstick. It doesn't logically follow that we should, in our aero engines , just accept the view that it is the best for us in our aircraft.. Do we apply the same logic to the airframe and tyres and brakes? No you don't you replace and inspect components. Same as in a Jabiru motor. Do you want the Rotec Radial to be subject to the same criteria? because it may need the same attention. If Not Why not? and we go on from there do we? Logically more stringent requirements for working on engines . We are dumbing down things is we go this way. Get the information out about the DETAILS of the problems with Jabiru and let the people and the companies decide what the market is. You make your own luck to a great extent, by your approach not the engine you fit. No one's forcing anybody to buy any particular engine. I HOPE Nev. 1 1
motzartmerv Posted November 27, 2014 Posted November 27, 2014 Would be great if jab optioned rotaxes. :)
facthunter Posted November 27, 2014 Posted November 27, 2014 Andy I'm not saying you CAN'T make the comparison, but it's not the only way to address the subject. I keep bring up other choices but all we get here is the Ford ? Holden mentality. The Jabiru has problems for sure, But I'll still fly in one. I don't particularly want to fly in a 912 p0wered aircraft, exclusively,, and all the others are not much better than Jabiru, so if you are going after Jabiru why wouldn't the same scrutiny be applied to all the others? That's my point. When I mention other engines I get accused of getting off the subject, but I do it for a reason. You have to think about the others if you are going to apply the criteria that all engines have to be as good as a 80 HP 912???. Things go wrong with them too you know. I've never terminated a flight prematurely with a Jabiru engine plane. Nev 2 2 1
microman Posted November 27, 2014 Posted November 27, 2014 I just had my 912S gearbox overhauled - engine had done approx 1500 hrs - cost - around $2800 plus labour. Also had the inlet valves replaced, valve seats cut and carbs rebuilt (needles, jets, floats, o rings etc). Pistons, rings and bores all good for another 1500 hrs. Also got another 150 rpm! I had previously done the carb rubbers and hoses. Thats about it as far as maintenance goes - apart from 100 hourlys of course. Wouldn't touch a Jabiru under any circumstances after hearing of many bad experiences over this side of the ditch. Having said that I have real sympathy with all who have supported a locally-made product - its just very unfair that you have been used for testing and development purposes. 1 1
gandalph Posted November 27, 2014 Posted November 27, 2014 Bruce you need to address the 40 odd engine failures, that's the issue. Your argument that raising safety standards is a bad idea because you haven't had an accident is intriguing but ultimately pointless. No he doesn't FT . He should, and he has, given a factual account of HIS experience with His engine. He shouldn't even try to address the "40 odd" incidents because he most likely doesn't have factual information on the cause of those incidents similarly to many other posters in this forum. Note that I called them incidents not engine failures because that it the terminology that CASA and the RAA have used. It removes some of the hyperbole that others have tried ti introduce to this discussion. More light and less heat would be useful . Intriguing but pointless is a charge that could be laid against so many of the posts in this forum. 2 3 1
bexrbetter Posted November 27, 2014 Posted November 27, 2014 They sell cars on the basis of the owner never lifting the bonnet and half the time you can't even find a dipstick. It doesn't logically follow that we should, in our aero engines , just accept the view that it is the best for us in our aircraft.. Apparently my standards are higher than a number of aviators. Considerably. That's for another thread though me thinks. 1
fly_tornado Posted November 27, 2014 Posted November 27, 2014 @gandalph every non Jabiru owner should put in a submission like "don't punish us for Jabirus mistakes" 2
motzartmerv Posted November 27, 2014 Posted November 27, 2014 The Jabiru has problems for sure, But I'll still fly in one. I Would you send your 15 year old daughter solo in one? 1 1
bexrbetter Posted November 27, 2014 Posted November 27, 2014 Would you send your 15 year old daughter solo in one? Safer than sending her up there with some young horny bloke! 4 1
fly_tornado Posted November 27, 2014 Posted November 27, 2014 Would you send your horny teenage son up in one solo?
gandalph Posted November 27, 2014 Posted November 27, 2014 @gandalph every non Jabiru owner should put in a submission like "don't punish us for Jabirus mistakes" You mean along the lines of "CASA, please investigate them, but please, oh! please don't investigate us." ? Sorry FT but that genie has already been let out of the bottle.
Guest Maj Millard Posted November 27, 2014 Posted November 27, 2014 Oh yea ok. Most pilots dont even notice the rough range, and as you say, if it not in a 'spot' where your likely to leave it, its not a concern.. Don, Motz.....I've done a lot of work on 912s over the years and a lot of flying with them, and I am not familiar with ' rough spots' in the rev range. That is not normal..or acceptable....something is amiss or out of wack there. Additionally I rarely pneumatically sync carbs. If you read the latest Rotax survice-info on the subject they recommend you perform the mechanical synchronisation first ( IE: mechanically setting up the position of the throttle lever arm ( butterfly posn) ..and then...and only then if necessary perform a Pneumatic sync. In my experience, in 99% percent of cases, the mechanical synce will do it every time,but not many people know this because they haven 't read the book .........and even fewer want to believe it works. Additionally another area that causes untold idle and running problems is the carb- bowl ambient air tubes, and the condition of the carb bowl gaskets. Both can have big effects on the fuel level in the fuel bowl. Leave the clear plastic tubes short, and where the are and all will be well. Spark plugs ...Rotax recommend gapping between .022- .027 "....I like .024" and that's what I've run for years. ( not the 914 or 912iS)
motzartmerv Posted November 27, 2014 Posted November 27, 2014 Thanks Maj.. The symptoms Ive found (on all rotaxes Ive flown) are hardly desernable. Using the term "rough spot" is probably not accurate. They all ( in my experience) have that range where it happens. maybe my "pants" are more sensitive then yours...lol..But ive felt it in every 912 ive flown.. Some worse than others. I will get the L2 to look into it again. Ps, my old XU1 Torry used to do exactly the same thing!!
kgwilson Posted November 27, 2014 Posted November 27, 2014 I think a new thread entitled "Rotax 912/914 series engine maintenance" should be started. That seems to be what the last few pages of this thread have been about. 5 2
gandalph Posted November 27, 2014 Posted November 27, 2014 I think a new thread entitled "Rotax 912/914 series engine maintenance" should be started. That seems to be what the last few pages of this thread have been about. Good idea, but be careful, CASA could be watching just waiting to pounce 1 1
facthunter Posted November 27, 2014 Posted November 27, 2014 The question was asked of me re sending various people solo in a Jab. . I would be more concerned about their flying standard than the engines reliability. Nev 8 1
motzartmerv Posted November 27, 2014 Posted November 27, 2014 That's a given. Doesn't answer the question tho. 2
facthunter Posted November 27, 2014 Posted November 27, 2014 It puts it into perspective. I had a think about it and that is my honest answer.. The only incident I can personally recall is someone doing an overshoot who had left the carb heat on, and fortunately aborted the take off in time. Another time I felt the compression on one and had the tappets checked . Nev
motzartmerv Posted November 27, 2014 Posted November 27, 2014 It was a loaded question, I appolagise for that. But I aimed it at you as you are probably one of the most experienced instructors in here, and I'm interested to discuss how this, even just proposed, action will make us ALL think long and hard about sending people solo behind jabs. If the worst case happened, I'm sure some smart a$$ lawyer could find a way to use this " draft" to prove neglect on our part ( the instructor) . Risk being defined as " the likelihood of an occurrence AND the outcome of the occurrence. If the outcome would mean we can be held liable, then all of a sudden, we are running a big risk. 1
facthunter Posted November 27, 2014 Posted November 27, 2014 Merv. there are certain airports that are in built up areas I wouldn't operate single engine training aircraft from. I try to keep things very much in context. Fuel starvation is probably the most common cause of engine failure. Some of the Cessna /piper fuel selectors were just an accident going somewhere to happen.. YOU are right to be concerned. Your experience is very different from mine, re the Jab engines. Instructors and Operators have to be worried about liabilities. Pilots too unless your boss takes care of it with some very good cover. There's always been a lot of things "not right" with Aviation at ALL levels. Things are not what they seem. Sometimes. Corners are cut, and that is not the way it should be. (I'm not referring to the RAAus here).. Nev
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