"Jaberoo" down (Mildura this time)

[David Isaac]

FFS the better question is why is there any need to do this on a certified engine FFS.

 

 

[Teckair]

We have a system designed for different times where anybody who buys an aircraft automatically becomes a L1 maintainer regardless of their ability and can take unsuspecting passengers flying.

 

 

[David Isaac]

We have a system designed for different times where anybody who buys an aircraft automatically becomes a L1 maintainer regardless of their ability and can take unsuspecting passengers flying.

Yes we do Richard, but people don't seem to fiddle with the Rotax or Lycoming series ..... why is that .... possibly because there is NO NEED to do so. Do you hear a Rotax (Bombardier) director suggesting you should check the guides every time the rocker covers are off ... or use a hand reamer FFS. Why are the rocker covers off so regularly, does this fundamental stuff escape everyone's fundamental logical thinking???????

 

 

[Dafydd Llewellyn]

FFS the better question is why is there any need to do this on a certified engine FFS.

Routine maintenance. Being certificated (NOT certified) does not remove the necessity for maintenance. The fact that it's necessary suggests that the valve guide temperatures are a bit on the high side - which again says that the CHT is getting a tad higher than was demonstrated during the 50 hour certification endurance run.

The temperature limits given in the TCDS are based on the temperatures that were exceeded for at least 50% of the endurance run; that's how they were established in the first place. The engine has to be run for 25 2-hour blocks, during the first hour of which the power is varied from idle to takeoff power; and the second hour is held at maximum continuous power, and red-line temperatures. CASA sits-in on all such tests. The engine is stripped and inspected afterwards, and carbon build-up in the guides would have been seen - so one must therefore deduce that if they are carboning up in service, then the CHT and/or the EGT are exceeding the TCDS limits. Hence my comments re the cold junctions.

 

I don't think you are correct re Lycomings etc; it doesn't have to be done frequently, but those air-cooled engines all run very close to limiting conditions for the exhaust valve guides. Continental has gone through about four changes in exhaust guide material over the years, and they still give trouble. The Rotax has liquid-cooled heads, whose main advantage is that they make it easier to cool the exhaust guides. Some Lycomings have oil passages in the head to try to reduce the guide temperatures; I hate to imaging what the maintenance issues are when those passages carbon up, as they must. Cars don't do it because they do not run the same duty cycle as an aero engine.

 

 

[fly_tornado]

The BMW boxers use oil injection on the back side of the pistons and the exhaust valve area in the head. BMW must take this seriously because its the only engine I know of that comes standard with 2 oil pumps, the cooler pump is a low pressure centrifugal type (no moving parts) and a thermostat on the oil coolers.

 

 

[Bandit12]

Statistics ain't so bad - it's the agenda of the person running (or asking for) the analysis, or the complete lack of understanding about how to use them that is the real problem.....

 

But the internet, now that's definitely all bad

 

 

[David Isaac]

......... or the complete lack of understanding about how to use them that is the real problem.....

I take a more experienced approach to statistics Bandit and I agree with you, however, in some of my experience it is the absolute knowledge of how to manipulate statistics to prove a theory or actuality to the point of fraudulent misconduct that I have found, and this is the point that Winston Churchill was making in his famous statement above.

 

 

[David Isaac]

Routine maintenance. Being certificated (NOT certified) does not remove the necessity for maintenance. The fact that it's necessary suggests that the valve guide temperatures are a bit on the high side - which again says that the CHT is getting a tad higher than was demonstrated during the 50 hour certification endurance run.............

Dafydd, I can accept required maintenance if it is clearly documented, but not if it attempts to compensate for poor design. And clearly these valve guide and valve issues point to over temp. If the engine is exceeding certificated temperatures in normal use and application then I would allege the manufacturer is misrepresenting to the consumer that the engine is certificated and Mr Stiff's pontifications on Jabbachat about illegal changes by owners removing the certification of his engines should equally apply to his factory installations where such factory installations cause in normal use, the engine to exceed its certificated approved temperatures.

 

 

[Dafydd Llewellyn]

In the interests of a better general understanding, here's (part of) what it takes to type-certificate an engine for a recreational aeroplane:

 

The temperature limits given in the engine TCDS (look it up on the CASA website) are determined as a result of this test.

 

 

 

[Dafydd Llewellyn]

Dafydd, I can accept required maintenance if it is clearly documented, but not if it attempts to compensate for poor design. And clearly these valve guide and valve issues point to over temp. If the engine is exceeding certificated temperatures in normal use and application then I would allege the manufacturer is misrepresenting to the consumer that the engine is certificated and Mr Stiff's pontifications on Jabbachat about illegal changes by owners removing the certification of his engines should equally apply to his factory installations where such factory installations cause in normal use, the engine to exceed its certificated approved temperatures.

Um - your reasoning is a bit garbled, I think.

Firstly, the Jab 2200 J and 2200C ARE certificated - you can look up the Type certificated Data Sheet on the CASA website. That means, CASA was (rightly or wrongly) satisfied that the engine met the certification requirement of the stated certification basis (JAR 22H); and the operating limits were set, as they normally are, on the basis of that testing. Thems is facts. So Jabiru is not misrepresenting that the engines are certificated. I think the reality is that people do not comprehend what the existence of a Type certificate actually means. I've tried to explain one facet of that above.

 

Secondly, if the engines are exceeding their temperature limitations in normal service, that is an issue of either the engine installation in the aircraft not providing sufficient cooling, OR it's an issue of the operator using it in such a way that the limits are being exceeded. The certification requirements for the AIRCRAFT demand that the engine must not exceed its stated temperature limits in a maximum-performance climb at Vy (best climb rate speed). It does NOT demand that the engine must not exceed its stated temperature limits below that speed - for example, at Vx (best climb gradient speed). So it is quite possible to overtemp a certificated engine in a certificated aircraft by poor operation. That's why the thing is fitted with temperature instruments.

 

If you are demanding that the design of the engine and the design of the aircraft should be such that no matter what the operator does, it's impossible to exceed limits, you are demanding more than the certification standards call for. This means, you do not have a proper understanding of what Type certification is all about; and that is a general problem throughout the aviation industry, I'm sorry to say. Most people understand that a pilot needs to comprehend that if he exceeds the flight envelope limits, he can pull the wings off. Similarly, if he exceeds the certificated operating conditions for the engine, things can come unstuck there also.

 

I am NOT trying to put all the blame onto the operators of Jabiru engines; but please get your facts straight.

 

I do suspect that people are inadvertantly exceeding the temperature limits, because of cold junction errors. The Jabiru engine installation manual gives clear guidance on the location of the cold junction and its intended temperature. I do not know whether locating it there actually gives that temperature or under what flight conditions it may do so. I do not know whether the temperature limits established during the 50 hour endurance test are sufficiently conservative in the longer term; it's definitely desirable to stay well within them, but you better make sure the gauge is telling the truth. Both the aircraft and the engine could no doubt be improved in these regards - but you are incorrect in saying that they are not certificated.

 

Perhaps the certification standards need to be tightened-up. You could stick to FAR 23 aircraft, of course, which do have somewhat higher standards here - but the clamour 20 years ago was for relaxed certification standards, in order to make aeroplanes more affordable. You can't have it both ways.

 

 

[David Isaac]

Um - your reasoning is a bit garbled, I think.If you are demanding This means, you do not have a proper understanding of what Type certification is all about; and that is a general problem throughout the aviation industry, I'm sorry to say. Most people understand that a pilot needs to comprehend that if he exceeds the flight envelope limits, he can pull the wings off. Similarly, if he exceeds the certificated operating conditions for the engine, things can come unstuck there also.

 

I am NOT trying to put all the blame onto the operators of Jabiru engines; but please get your facts straight.

Firstly I am absolutely not saying that "the design of the engine and the design of the aircraft should be such that no matter what the operator does, it's impossible to exceed limits, you are demanding more than the certification standards call for."

 

I have no idea how you would deduct that from what I said. I have been flying GA aircraft since I was 16 years old and operated C180s, 182s, 185s, 206s all with cowl flaps and I understand operating engines properly and I have an extensive knowledge of what goes on internally in an engine and the issues surrounding operating temperature.

 

I did say "exceeding certificated temperatures in normal use and application..." and by that I mean operating the aircraft normally as in accordance with the POH.

 

Just to clarify that I do not consider I am ignorant on these issues. If you operate the aircraft in accordance with the POH (normally) there should not be over temp issues unless the PIC is asleep.

 

 

[Dafydd Llewellyn]

Firstly I am absolutely not saying that "the that the design of the engine and the design of the aircraft should be such that no matter what the operator does, it's impossible to exceed limits, you are demanding more than the certification standards call for." I have no idea how you would deduct that from what I said. I have been flying GA aircraft since I was 16 years old and operated C180s, 182s, 185s, 206s all with cowl flaps and I understand operating engines properly and I have an extensive knowledge of what goes on internally in an engine and the issues surrounding operating temperature. I did say "exceeding certificated temperatures in normal use and application..." and by that I mean operating the aircraft normally as in accordance with the POH.Just to clarify that I do not consider that I am ignorant on these issues. If you aoperating the aircraft in accordance with the POH (normally) ther should not normally be over temp isues unless the PIC is asleep.

Yep, I agree with that.

 

 

[Guest Andys@coffs]

Guys

 

You are both missing the point.

 

As delivered from the factory how many CHT gauges are fitted? Is it that there is a CHT thermocouple fitted to each cylinder head???? I think not, and therefore the best thing that an operator can do is to have fitted a CHT thermocouple and display for each cylinder. At that stage you then have an opportunity to say did I, or did I not operate IAW the limitations set. For those that operate with the one or 2 provided...good luck with ever understanding if the rest are operating inside or outside of limits.

 

My L2 who rebuilt my J3300 contends that the POH CHT maximums are in fact well in excess of what the engine can handle.........Reality in my aircraft is that the differences from Cylinder to Cylinder are indeed significant, you can have one exceeding what you should and another that hasn't even reached the average operating temps. The Jabiru Australia site has all the manuals and the POH identifies max CHT temps. The American Jabiru website specifies lower CHT temps as maximum. The American site isn't Jabiru Australia, its their USA agent so as such there isn't a conflict at OEM level, but it is an interesting fact nonetheless.

 

These like most other comments are personal observation without any scientific fact. So at least worth the zero cents paid for it.....

 

Andy

 

 

[Teckair]

Why are the rocker covers off so regularly, does this fundamental stuff escape everyone's fundamental logical thinking???????

I am not a Jabiru expert but from what I can gather Jabiru engines need more attention than some others, and it needs to be carried out by people with specific Jabiru knowledge and even then I think I would feel safer with a properly maintained Rotax two stroke. For that reason I would not buy one and avoid flying one which is a choice we all have.

 

Do you hear a Rotax (Bombardier) director suggesting you should check the guides every time the rocker covers are off

No and I doubt if Jabiru would recommend that either as it would require the heads to be removed.

 

or use a hand reamer FFS.

This not an unusual practice during an engine rebuild.

 

Why are the rocker covers off so regularly,

Probably to check the tappets on solid lifter motors.

 

does this fundamental stuff escape everyone's fundamental logical thinking???????

I don't think so, that's how the term Jab basher came about. What do you suggest be done about it David? Ground them all? Not a problem for me but... Who has caused these problems? Easy to blame Rod Stiff or the factory or RAAus but then the Jabiru prangs should be no secret and people still buy them, so who is really causing the problem?

 

 

[gandalph]

FFS the better question is why is there any need to do this on a certified engine FFS.

David, Read post # 109.

 

 

[Oscar]

FFS the better question is why is there any need to do this on a certified engine FFS.

David, I didn't ask any question. There sure are questions that Jabiru needs to address re the effectiveness of its cooling installations and I absolutely agree with that (and am in fact working on some ideas to make our Jab. engine cool far more effectively in critical areas), but there is another fundamental point that you have missed.

 

It is this: it was (at best, obliquely) suggested that Jabiru are conspiring to negate their warranty obligations, by requiring a tool 'that only the manufacturer has'. This was by someone who is self-evidently ignorant of even basic engine maintenance tools and therefore by definition ignorant of how to use them. As much as I think that piece by Rod Stiff was, to be polite, not at all well considered, his comments on a) the advisability of checking the valve guides for problems, b) indicating how to address any problems that may be determined, c) that this should not be done by people who do not have the correct equipment and the knowledge of how to use it, and d) listing what tools are required for the task, can in no way be considered a 'conspiracy' by anybody with a reasonably functioning intellect. It's up there with blaming the government for meteor strikes.

 

 

[bexrbetter]

Who has caused these problems?

You know these problems are consistent with owners throughout the world don't you? - eg. Europe and America. This isn't a case of a few haters in one forum ganging up against them.

 

Regardless of the engine being awesome or not, that point becomes moot if the common owner isn't capable of successfully living/maintaining with them.

 

 

[Dafydd Llewellyn]

I have to agree. So where does that logic take us? I have been overhauling a Blanik - and what comes to me from that, is that there are a lot of people out there who should not be allowed within 100 yards of an aircraft - 200 yards if they are holding a spanner. Some of the butchery on that aircraft was incredible. Some of the work was very good. It hung together despite the butchery because it was such a good design in the first place.

 

The whole basis of RAA etc was that the common aviation enthusiast was sufficiently competent to maintain his own aircraft. Are we getting to the point of disproving that?

 

 

[Dafydd Llewellyn]

There's a lot of work going on in that area; can't talk about it now.

 

 

[Dafydd Llewellyn]

Glad to hear that. But I don't think it's for general publication yet, either; that has to be Ian's option. The point is, whilst all this bitching is going on, there are people trying to do something about it. It has to go through the proper hoops.

 

 

[Oscar]

I heard Ian Bent is working on cowl mods to keep it all much coolerStay tuned

And a whole lot more, Deb, in a systematic research and development programme. I'm no expert but I believe you'll find that just about every 'questionable' area that is routinely discussed has been looked at and a whole lot of subtle stuff that only a deep research and development programme can discover has been investigated and considered. Information about MOST of that will become publicly available in the not-too-distant future, though some will be C-i-C, just as for any manufacturer.

 

 

[Teckair]

The whole basis of RAA etc was that the common aviation enthusiast was sufficiently competent to maintain his own aircraft. Are we getting to the point of disproving that?

Yes.

 

 

[Teckair]

if the common owner isn't capable of successfully living/maintaining with them.

That now is major problem that has to be addressed.

 

 

[alf jessup]

Can't blame the owners & maintainers all the time

 

To many inconsistencies in the engines themselves

 

 

[Oscar]

I have to agree. So where does that logic take us? I have been overhauling a Blanik - and what comes to me from that, is that there are a lot of people out there who should not be allowed within 100 yards of an aircraft - 200 yards if they are holding a spanner. Some of the butchery on that aircraft was incredible. Some of the work was very good. It hung together despite the butchery because it was such a good design in the first place.The whole basis of RAA etc was that the common aviation enthusiast was sufficiently competent to maintain his own aircraft. Are we getting to the point of disproving that?

I have a Jab that was a write-off following an EFATO that I am rebuilding. It spent almost all of its 2700+ hours life as a trainer (after being a Jabiru development 'mule'), on-the line, serviced by LAME's/L2's. My co-owner and I have dismantled, inspected, repaired etc. just about every square mm./nut and bolt on the damn thing.

 

Some of the work done - and bloody well signed-off, in later cases by an L2 who is now manufacturing aircraft - was bad beyond reasonable belief. Replacement of the front leg, leaving a near-25mm hole clear through the firewall and the steering rod-end (which is part of the rudder control system) bending against the side of the new hole to the point where the rod-end shaft was seriously bent? The rudder cable attached with the rod-end on the wrong side of the control horn, stressing the rod-end fitting? The entire rudder control system box moving on its rivets? Annual inspection reports entered and signed off - by said L2 - without airframe hours being recorded? New main legs installed with old - and in some cases, not the correct size- bolts in contravention of the factory instructions - again signed off by said L2.

 

If there is an airframe out there that has an enclosed cockpit, decent performance in all aspects, genuine and demonstrated survivability in the case of a crash, and a better 'intelligent and informed' owner-maintenance potential than a Jab., I invite its nomination. The engine, yes, requires a bit more than above-average owner/operator care, diligence and maintenance skills.

 

Jabs. aren't perfect for everybody; no aircraft is. But if you choose your aircraft on the basis of your skills, use, wallet and wants and accept the inevitable compromises that such choice imposes, then a Jab, -if it fits your user profile - is a damn good bang-for the-buck aircraft.